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  1. Chemistry Department Colloquium

    "Redox Hopping Water Oxidation Catalysis by Metal Organic Frameworks"

    Presented by Amanda Morris, Virginia Tech, Dept. of Chemistry

    Monday, March 9, 2020, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Gerald Manbeck

    Metal organic frameworks (MOFs) are supramolecular architectures comprised of metal nodes connected by multi-dentate organic/inorganic linkers. Incorporation of molecular chromophores into these solid-state structures has been exploited to develop luminescent sensors, light emitting diodes, photovoltaics, and photo/electro-catalysts. In terms of catalysis, the high surface area of MOFs can be exploited to produce a higher catalytic rate per geometric area than those realized by other approaches. The crux of catalysis, however, is diffusion. The Morris group has explored the diffusion of electrons and ions through MOFs as a function of applied electric field. The results indicate that under most cases, as expected, ion motion is restricted through the 3D MOF networks. The effect of ion size and electronic self-exchange rates will be presented. Additionally, the effect of 3D MOF structure and pore size will be discussed. We will conclude with a discussion of the implications for electrocatalytic water oxidation with respect to catalytic rate and turnovers.

  2. Environmental & Climate Sciences Department Seminar

    "Dilution impacts on smoke aerosol aging and photochemistry: Evidence in BBOP data"

    Presented by Jeffrey Pierce, Colorado State University

    Thursday, January 9, 2020, 11 am
    John Dunn Seminar Room, Bldg. 463

    Hosted by: Art Sedlacek

    Smoke aerosol properties and ozone evolve within plumes through physical and chemical processes, impacting smoke climate and health impacts. Many of these physical and chemical processes, in theory, depend strongly on smoke concentrations. Hence, the initial concentrations and dilution rates should affect smoke aging. In general, plumes from small fires should dilute more rapidly than those from large fires, all else equal; and in recent publications, we have used theory to demonstrate the smoke properties from small fires should evolve differently than those from large fires. However, until recently, we have been unable to test these findings with measurements due to a lack of Langrangian-style smoke aging field studies of small fires (due to the challenge of following small, fast-diluting plumes with time). In this talk, I will discuss how we have used observations of concentration gradients in large plumes from the Pacific Northwest portion of BBOP campaign to test these hypotheses. Using the high time resolution BBOP measurements, we have separated the dilute edges of the large plumes from the concentrated cores. We expect that the dilute edges of large plumes have similar chemical and physical process rates as small, fast-diluting plumes. The BBOP data show that the dilute portions of plumes (1) have faster number losses and diameter growth from coagulation, (2) transition more quickly POA-like to SOA-like aerosol composition potentially through faster OA evaporation and faster photochemistry, and (3) have higher enhancements of ozone. We recommend that future smoke studies compare concentrate plume cores to dilute edges to help elucidate physical/chemical processes and understand inter-plume differences.

  3. Chemistry Department Colloquium

    "Design of high voltage all-solid-state batteries based on sulfide electrolytes"

    Presented by Xin Li, John A. Paulson School of Engineering and Applied Sciences, Harvard University

    Tuesday, January 7, 2020, 2 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Enyuan Hu

    Ceramic sulfide solid-electrolytes are amongst the most promising materials for enabling solid-state lithium ion batteries. The ionic conductivities can meet or exceed liquid-electrolytes for such ceramic sulfides, however, there is a theoretical concern about the narrow electrochemical stability window of approximately 1.7-2.1 V vs lithium metal. In addition, ceramic sulfides are frequently plagued by interfacial reactions when combined with common electrode active materials. In this talk, methods for the stabilization of both the bulk electrochemical decompositions and the interfacial reactions will be discussed. Ceramic sulfides are known to substantially swell during electrochemical decay. Such swelling has been shown to provide viable means by which to stabilize electrochemical decomposition in lithium ion batteries. Experimental evidence and theoretical understanding of stability window expansion as the result of mechanical constriction will be discussed. An advanced mechanical constriction technique is applied on all-solid-state batteries constructed with Li10GeP2S12 (LGPS) as the electrolyte and lithium metal as the anode. The decomposition pathway of LGPS at the anode interface is modified by this mechanical constriction and the growth of lithium dendrite is inhibited, leading to excellent rate and cycling performances. On the cathode side, 5V all-solid-state batteries using layered LiCoO2 and spinel as cathodes will be presented and the stabilization mechanisms will be discussed. A combination of electrochemical battery tests, SEM, XAS, XPS and XRD characterizations, and DFT simulations was used. Biosketch Xin Li is an associate professor of materials science at School of Engineering and Applied Sciences (SEAS) at Harvard University, who was an assistant professor at SEAS from 2015 to 2019. Xin Li's research group designs new energy storage materials through advanced characterizations and simulations, with the current focus on solid s

  4. Chemistry Department Colloquium

    "Electronic Cooperativity in Supported Single and Multinuclear-Sites for Catalytic C-C and C-H Bond Functionalization"

    Presented by Dr. Massimiliano Delferro, Argonne National Laboratory

    Monday, October 28, 2019, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Sanjaya Senanayake

    Systematic study of the interactions between organometallic catalysts and metal oxide support materials is essential for the realization of rational design in heterogeneous catalysis. In this talk, I will describe the stoichiometric and catalytic chemistry of a series of organometallic complex chemisorbed on a variety of metal oxides as a multifaceted probe for stereoelectronic communication between the support and organometallic center. Electrophilic bond activation was explored in the context of stoichiometric hydrogenolysis as well as catalytic hydrogenation, dehydrogenation, and H/D exchange. Strongly acidic modified metal oxides such as sulfated zirconia engender high levels of activity toward electrophilic bond activation of both sp2 and sp3 C–H bonds, including the rapid activation of methane at room temperature; however, the global trend for the supports studied here does not suggest a direct correlation between activity and surface Brønsted acidity, and more complex metal surface interactions are at play.

  5. NSLS-II Friday Lunchtime Seminar

    "Plant-fungal symbiosis and their potential impacts on terrestrial biogeochemistry"

    Presented by Ko-Hsuan (Koko) Chen, University of Florida

    Friday, October 25, 2019, 12 pm
    NSLS-II Bldg. 743 Room 156

    Hosted by: Ignace Jarrige

    Fungi are associated with all lineages of land plants. While plant-fungal symbiosis is common, many of their interactions, ranging from mutualism, commensalism, to parasitism are yet to be determined. As plant-fungal symbiosis are tightly linked to nutrient cycling, different interaction types have substantial impacts on biogeochemistry. Here, we will use two plant-fungal symbiosis examples: 1) Pine and their ectomycorrhizal fungi, and 2) mosses and their associated fungi, to illustrate how considering plant-fungal interaction and biogeochemistry together can further our understanding toward a better understanding of plant-fungal biology.

  6. Center for Functional Nanomaterials Seminar

    "Heterogeneous Chemistry at Liquid/Vapor Interfaces Investigated with Photoelectron Spectroscopy"

    Presented by Hendrik Bluhm, Fritz Haber Institute of the Max Planck Society, Department of Inorganic Chemistry, Faradayweg, Berlin, Germany

    Monday, October 21, 2019, 11 am
    Bldg.735 (CFN) 1st floor conference room

    Hosted by: Ashley Head

    Aqueous solution/vapor interfaces govern important phenomena in the environment and atmosphere, including the uptake and release of trace gases by aerosols and CO2 sequestration by the oceans.[1] A detailed understanding of these processes requires the investigation of liquid/vapor interfaces with chemical sensitivity and interface specificity under ambient conditions, i.e., temperatures above 200 K and water vapour pressures in the millibar to tens of millibar pressure range. This talk will discuss opportunities and challenges for investigations of liquid/vapor interfaces using X-ray photoelectron spectroscopy and describe some recent experiments that have focused on the propensity of certain ions and the role of surfactants at the liquid/vapor interface. [1] O. Björneholm et al., Chem. Rev. 116, 7698 (2016).

  7. Chemistry Department Seminar

    "Advancing Nanomaterials Research with In Situ TEM"

    Presented by Jordan Moering, Protochips, Inc. 3800 Gateway Centre Blvd, Morrisville NC, 27560

    Wednesday, October 9, 2019, 2 pm
    CFN, Bldg 735, Conference Room A

    Hosted by: Fernando Camino

    The advent of in situ thermal and electrical sample control within realistic environments has transformed the Transmission Electron Microscope (TEM) from a simple high-resolution image acquisition tool into a nanoscale materials research and development laboratory. For example, to support the growing need of photovoltaic and quantum materials researchers, the Fusion Select system couples precise pA-level electrical control with a friction-free tilting stage, allowing users to simultaneously characterize samples at high tilt and high temperature. Featuring a user-friendly software interface, a series of FIB-optimized sample supports, and extensive training material, the Fusion Select system is optimized for new users attempting their first in situ electrical or thermal TEM studies For environmental TEM analysis, the Catalysis Package for the Atmosphere System is the first commercial closed-cell system with an integrated mass spectrometer and flexible gas handling system specifically designed for catalyst materials research. Recognized as one of the top ten microscopy innovations of 2019, the Atmosphere system has been designed specifically for electron microscopy by maximizing gas mixing and pressure control while minimizing mechanical vibrations and new user learning curve. This talk will review these and other capabilities as they relate to the aims of the CFN – enabling external users to carry out high-impact nanoscience projects, while enhancing the in-house functional nanomaterial research conducted by staff scientists.

  8. Chemistry Department Colloquium

    "Coupling Molecular Catalysts with Light-Harvesting Surfaces for Solar CO2 Reduction"

    Presented by Gonghu Li, Dept. of Chemistry, University of New Hampshire

    Monday, October 7, 2019, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: David Grills and Anatoly Frenkel

    There is a critical need for robust photosynthetic systems that can achieve efficient solar fuel production by CO2 reduction or water splitting. We combine highly efficient molecular catalysts with light-harvesting solid surfaces for use in solar CO2 reduction. In particular, coordination complexes of rhenium and cobalt have been coupled with mesoporous SiO2, TiO2, C3N4, and Si nanostructures. A variety of techniques, including infrared and X-ray absorption spectroscopies, were utilized to investigate CO2-reduction catalysis in these hybrid systems. Appropriate covalent linkages and catalyst/surface interactions were found to be important in promoting selective CO2 reduction.

  9. Chemistry Department Seminar

    ""Probing the Excited-State Reactivity of Transition-Metal Compounds Using Photophysics""

    Presented by Dr. Daniela M. Arias-Rotondo, Department of Chemistry

    Monday, September 23, 2019, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Matt Bird

    Transition metal compounds are ubiquitous throughout the chemical sciences, their presence broadly impacting fields such as organic synthesis and solar energy conversion. This talk illustrates how spectroscopic techniques can be used to understand the intricacies of reactions involving transition metal compounds towards two different applications. The first part of this presentation will focus on the conservation of spin in chemical reactions. Our group has previously shown that spin must be conserved for energy transfer to occur.1 To further our understanding of the effect of spin on other types of reactions, we have combined Ru(II) polypyridyls and Fe(III) oxo/hydroxo-bridged dimers to study how the spin state of the acceptor affects the rate of electron transfer. Through a combination of time-resolved spectroscopy and electrochemical techniques we have shown that excited spin states may be involved in electron transfer, as was predicted by Bominaar and coworkers in their studies involving metalloproteins.2 The second half of this seminar describes the use of energy transfer to activate traditional organometallic catalysts to unlock novel reactivity patterns. In particular, we studied the use of an Ir(III) photosensitizer in combination with a Ni(II) catalyst in the coupling of aryl halides and carboxylic acids.3 Mechanistic studies showed that energy transfer from the photocatalyst to the nickel species promotes the latter to an excited state that can promote a novel C-O bond formation.

  10. Chemistry Department Colloquium

    "Oxygen Catalysis for Large Scale Solar Energy Harvesting and Storage"

    Presented by Dunwei Wang, Boston College

    Thursday, September 12, 2019, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Anatoly Frenkel

    : As we enter Anthropocene, it has become clearer than ever that a sustainable future will be one built on renewable energy resources. A critical challenge in realizing such a goal is to harvest and store renewable energy efficiently and inexpensively on a terawatt scale. Of the options that have been examined, using the energy to directly synthesize fuels stands out. When the renewable energy source is solar, the process is often referred to as artificial photosynthesis, highlighting the similarities with natural photosynthesis. Within this context, we have focused on understanding the detailed processes that are important to artificial photosynthesis. More specifically, a main thrust of our research has been water oxidation by photochemical reactions on the surface of inorganic materials. We strived to understand the detailed physical and chemical processes at the solid/liquid interface, with the goal of enabling facile electron extraction from water for the eventual proton reduction for hydrogen generation or the carbon dioxide reduction for the production of complex organic compounds. It was discovered that the light harvesting and catalytic components in an integrated system exerts profound influences on each other in a complex fashion. Detailed studies generated new insights into the water oxidation reactions at the molecular level, some of which was readily transferred to other reactions such as methane transformation. These efforts also inspired us to study oxygen catalysis in aprotic systems for applications with more immediate implications, such as metal air batteries.

  11. Atmospheric Chemistry Colloquium for Emerging Senior Scientist


    Saturday, July 27, 2019, 8 am
    Berkner Hall, Room B

    Hosted by: Ernie Lewis

  12. Atmospheric Chemistry Colloquium for Emerging Senior Scientist (ACCESS XV)


    Friday, July 26, 2019, 8 am
    Berkner Hall, Room B

    Hosted by: Ernie Lewis

  13. Chemistry Department Seminar

    "Nanoparticle Beam Deposition: A Novel Route to the Solvent-Free"

    Presented by Richard E. Palmer, Nanomaterials Lab, Swansea University, UK, United Kingdom

    Tuesday, July 16, 2019, 11 am
    Room 300, 3rd Floor, Chemistry Building 555

    Hosted by: Michael White

    Size-selected nanoparticles (atomic clusters), deposited onto supports from the beam in the absence of solvents, represent a new class of model systems for catalysis research and possibly small-scale manufacturing of selective catalysts. To translate these novel and well-controlled systems into practical use, two major challenges have to be addressed. (1) Very rarely have the actual structures of clusters been obtained from direct experimental measurements, so the metrology of these new material systems have to improve. The availability of aberration-corrected HAADF STEM is transforming our approach to this structure challenge [1,2]. I will address the atomic structures of size-selected Au clusters, deposited onto standard carbon TEM supports from a mass-selected cluster beam source. Specific examples considered are the "magic number clusters" Au20, Au55, Au309, Au561, and Au923. The results expose, for example, the metastability of frequently observed structures, the nature of equilibrium amongst competing isomers, and the cluster surface and core melting points as a function of size. The cluster beam approach is applicable to more complex nanoparticles too, such as oxides and sulphides [3]. (2) A second major challenge is scale-up, needed to enable the beautiful physics and chemistry of clusters to be exploited in applications, notably catalysis [4]. Compared with the (powerful) colloidal route, the nanocluster beam approach [5] involves no solvents and no ligands, while particles can be size selected by a mass filter, and alloys with challenging combinations of metals can readily be produced. However, the cluster approach has been held back by extremely low rates of particle production, only 1 microgram per hour, sufficient for surface science studies but well below what is desirable even for research-level realistic reaction studies. In an effort to address this scale-up challenge, I will discuss the development of a new kind of nanop

  14. Nuclear Physics Seminar

    "Charm hadron collective flow and charm hadrochemistry in heavy-ion collisions"

    Presented by Xin Dong, Lawrence Berkeley National Laboratory

    Tuesday, July 2, 2019, 10 am
    Small Seminar Room, Bldg. 510

    Hosted by: Lijuan Ruan

    Heavy quark transport offers unique insight into the microscopic picture of the sQGP created in heavy-ion collisions. One central focus of heavy quark program is to determine the heavy quark spatial diffusion coefficient and its momentum and temperature dependence. This requires precise measurements of heavy flavor hadron production and their collective flow over a broad momentum region. In the meantime, heavy quark hadrochemistry, the abundance of various heavy flavor hadrons, provides special sensitivity to the QCD hadronization and also plays an important role for the interpretation of heavy flavor hadron data in order to constrain the heavy quark spatial diffusion coefficient of the sQGP. In this seminar, I will focus on the recent STAR results of charm hadron D0, D+/-, D*, Ds, Lambda_c production and D0 radial and elliptic flow in heavy-ion collisions utilizing the state-of-the-art silicon pixel detector, the Heavy Flavor Tracker. These data will be compared to measurements from other experiments at RHIC and the LHC as well as various model calculations. I will then discuss how these data will help us better understand the sQGP properties and its hadronization. Finally, I will present a personal view of future heavy quark measurements at RHIC.

  15. Chemistry Department Seminar

    "Chemical and Electrochemical Studies of Half-Sandwich Rhodium Complexes"

    Presented by James D. Blakemore, Dept. of Chemistry, University of Kansas

    Tuesday, July 2, 2019, 10 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Etsuko Fujita

    Understanding the management of protons and electrons (reducing equivalents) by transition metal compounds is an active area of research, in part because of the role of reduced and/or protonated complexes in catalysis and energy conversion. We have been studying the chemistry of half-sandwich rhodium complexes in this regard, in order to reveal the influence of ligand structure on the outcomes of reduction and protonation reactions. Here, recent results on use of hybrid [P,N] and dipyridylmethane [N,N] chelate ligands will be discussed, including preparation and characterization of new compounds, chemical and electrochemical experiments aimed at elucidating new reactivity patterns, and studies of hydrogen evolution. Taken together, the results suggest that relatively underexplored ligands, as analogues of common diimine and diphosphine chelates, offer interesting new opportunities for influencing the properties and reactivity of metal complexes with protons and electrons.

  16. Chemistry Department Colloquium

    "Recent Advances in Soft X-ray Spectroscopy towards a Direct and Reliable Probe of Chemistry in Batteries"

    Presented by Wanli Yang, Lawrence Berkeley National Laboratory

    Thursday, June 27, 2019, 2 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Enyuan Hu

    The pressing demand of improved energy storage systems, especially for electric vehicles and green-grid, calls for speedy strategies for developing materials based on advanced analytic tools. Synchrotron based soft x-ray core-level spectroscopy is one of such incisive tools that probes the key electronic states pertaining to the performance of batteries. This colloquium starts with an in-depth introduction of conventional soft X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) with its applications in detecting the critical electron states in battery materials from binder to electrodes. The experimental results provide both general understandings and quantitative analysis of the transition-metal (TM) reactions at different electrochemical states, through direct probes of the K-edges (2p states) of low-Z elements such as C, O, N, and the L-edges (3d states) of 3d TMs. More importantly, however, we clarify that conventional spectroscopic experiments based on XAS do not really provide the claimed "elemental sensitivity" in either the O-K or the TM-L in the bulk-sensitive photon-in-photon-out mode, thus failing to detect the true signature of the bulk redox reactions of lower TMs, and especially, Oxygen [1]. This naturally requires advanced spectroscopic probes beyond conventional XAS for disentangle the mixed signals in oxides. We show that high-efficiency mapping of resonant inelastic X-ray scattering (mRIXS) beautifully solves the problems in both TM-L and O-K edge characterizations, providing clear experimental signatures of both the TM [2] and Oxygen [3] redox that cannot be distinguished in conventional XAS. This colloquium does not focus on technical discussions of a specific scientific study, instead, the focus will be on clarifying the principle and on how to correctly interpreting soft X-ray spectroscopic data instead of following popular misinterpretations. We finally note that recent advances in bo

  17. Chemistry Department Colloquium

    "Molecular catalysis of small molecules activation."

    Presented by Cyrille Costentin, Université Paris Diderot, France

    Monday, June 17, 2019, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Gerald Manbeck

    Solar-driven electrochemical splitting of water to molecular hydrogen and oxygen, along with the reduction of carbon dioxide are small molecule transformations that hold promise as routes of storing sunlight in energy-dense chemical bonds. Activation penalties require the help of catalysts, usually transition metal derivatives. We will provide the basic principles of molecular catalysis of electrochemical reactions based on the use of cyclic voltammetry as an analytical tool. Two examples will be discussed in details: (i) catalysis of the CO2-to-CO conversion with iron porphyrins to illustrate how mechanism analysis can lead to an intelligent design of a catalyst; new results on CO2 vs. acid reduction selectivity will be discussed; (ii) catalysis of the O2-to-H2O conversion with manganese porphyrins showing the crucial role of proton couple electron transfer (PCET) in the process.

  18. Chemistry Department Seminar

    "Designing Dopants to Shield Anion Electrostatics in Doped Conjugated Polymers to Obtain Highly Mobile and Delocalized Carriers"

    Presented by Taylor Aubry, UCLA

    Thursday, May 23, 2019, 11 am
    Room 300, 3rd Floor - Chemistry Bldg. 555

    Hosted by: Matthew Bird

    Doping conjugated polymers is an effective way to tune their electronic properties for thin-film electronics applications. Chemical doping of semiconducting polymers involves the introduction of a strong electron acceptor or donor molecule that can undergo charge transfer (CT) with the polymer. The CT reaction creates electrical carriers on the polymer chain (usually positive polarons a.k.a. holes) while the dopant molecules remain in the film as counterions. Undesirably, strong electrostatic attraction from the anions of most dopants will localize the polarons and reduce their mobility. We employ a new strategy utilizing substituted icosahedral dodecaborane (DDB) clusters as molecular dopants for conjugated polymers. DDBs provide a unique system in which the redox potential of the dopant can be rationally tuned via modification of the substituents without significant change to the size or shape of the dopant molecule. These clusters allow us to disentangle the effects of energetic offset on the production of free and trapped carriers in DDB-doped poly-3-hexylthiophene (P3HT) films. We find that by designing our cluster to have a high redox potential and steric protection of the core-localized electron density, highly delocalized polarons with mobilities equivalent to films doped with no anions present are obtained.1 P3HT films doped with these boron clusters have conductivities and polaron mobilities roughly an order of magnitude higher than films doped with conventional small-molecule dopants such as 2,3,5,6-tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4TCNQ). The spectral shape of the IR-region absorption for our DDB-doped polymer film closely matches the calculated theoretical spectrum for the anion at infinite distance from the polaron.2 We therefore conclude that these DDB clusters are able to effectively spatially separate the counterion. Moreover, nearly all DDB-produced carriers are free, while it has been shown that small m

  19. Chemistry Department Seminar

    "Atomic Quantum Clusters: Novel Materials at Sub-Nanometric Level"

    Presented by David Buceta, Nanomag Group, University of Santiago de Compostela, E-15782 Santiago de, Spain

    Wednesday, May 22, 2019, 11 am
    Room 300, Chemistry Bldg. 555 - 3rd floor

    Hosted by: Jose Rodriguez

    Atomic Quantum Clusters (AQCs) are formed by a small number of atoms (< ≈ 150) and represent a new family of compounds with novel and fascinating properties, which strongly differ from both, bulk and nanoparticles of the same material. For example, fluorescent, magnetic, catalytic, etc. properties have been found in AQCs1, which are not exhibited for the same material in larger sizes. In the last years soft chemical methods have been developed to synthesize AQCs without using protecting or capping ligands2, which may hinder their properties. This offers now the possibility to explore their properties in detail. In this talk it will be firstly summarized the state-of-the art of the kinetic-control synthesis methods, explaining in detail the mechanisms involved in such methods3. To show the precise control on the size of AQCs, which can be achieved with these methods, we will explain the synthesis of monodisperse samples of Cu5-AQCs and Ag3-AQCs. Secondly, we will focus on some important applications of clusters in catalysis, highlighting the particular consequences in biomedicine4.

  20. Chemistry Department Colloquium

    "Anineutrino Reactor Monitoring"

    Presented by Professor Patrick Huber, Virginia Tech

    Monday, March 4, 2019, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Minfang Yeh

    Nuclear reactors are the brightest man-made neutrino sources and have been the workhorse of neutrino physics since the discovery of the neutrino. In the 1970s Lev Mikaelyan realized that neutrinos also can be used to learn about the internal state of a nuclear reactor. The past decade has seen a significant increase in the interest in reactor neutrinos, thanks to the theta-13 experiments and the search for sterile neutrinos. In particular, I will discuss case studies we have performed for the historical case of the 1990s nuclear crisis in the Democratic People's Republic of Korea and for the IR-40 reactor in Iran. I will report on on-going efforts to develop suitable detectors for surface deployment close to a nuclear reactor and comment on the role coherent elastic neutrino nucleus scattering may play. With the most recent results from PROSPECT, CHANDLER and others, for the first time, a real world capability exists and I will present recent efforts by an international group of reactor neutrino experts with regards to North Korea, which were published in Science [Science, 362, (2018) 649-650)].

  21. Chemistry Department Colloquium

    "Atomic Simulation and Data Science Applied to Catalysis"

    Presented by Eric A. Walker, State University of NY at Buffalo

    Tuesday, February 19, 2019, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Ping Liu

    Atomic simulation is able to solve more chemical problems than ever before due to advances in high performance computing and data science tools. Two case studies are presented to illustrate this point. One case study is the water-gas shift reaction catalyzed by platinum clusters deposited on metal oxide (Pt/MO2). The water-gas shift reaction is the most widely applied reaction in industry for the production of hydrogen which is an environmentally-friendly fuel. Furthermore, water-gas shift may be conducted on domestically produced shale gas, alleviating foreign dependence on oil. Three hypotheses regarding the active site for the water–gas shift reaction are the interface edge of Pt/MO2 catalysts, the interface corner, and the platinum terrace (pure platinum). The hypotheses are tested against experimental kinetic data. Uncertainties associated with density functional theory (DFT) calculations and model errors of microkinetic models of the active sites are informed and verified using Bayesian inference and predictive validation on the experiments. Our results suggest the metal oxide support is essential for the activity of the catalyst for water-gas shift, which aids the rational design of catalysts for the water-gas shift reaction. In the second case study, large data sets of organic reactions are investigated using machine learning tools. Reactions which are not labeled with a solvent are automatically labeled, which impacts automated chemical process design and may be utilized as an every-day tool by chemists. The machine learning solvent selections are tested against an expert chemist. In a broad sense, the methods developed within this work improve the reliability of atomic simulations and the incorporation of machine learning to catalysis research.

  22. Chemistry Department Seminar

    "Theoretical and in situ studies for the reactivity of metal-ceria (111) surfac-es: Importance of strong metal-support interactions"

    Presented by M. Verónica Ganduglia-Pirovano, Instituto de Catálisis y Petroleoquímica Consejo Superior de Investigaciones Científicas,, Spain

    Friday, February 15, 2019, 11 am
    Room 300, 3rd floor, Chemistry Bldg. 555

    Hosted by: Sanjaya Senanayake

    Metal-ceria catalysts are promising systems for industrially important reactions such as the water-gas shift reaction for hydrogen production, methane dry reforming (DRM: CH4+CO2 ? 2H2+2CO), and the direct conversion of methane to methanol (DMTM: CH4+ ½ O2 ? CH3OH). However, the complexity of real (powder) catalysts hinders the fundamental understanding of how they work, which is essential for their rational design. Specifically, the role of ceria in the catalytic activity of ceria-based systems is still not fully understood. To unravel it, well-defined ceria-based model cata-lysts consisting of metal nanoparticles deposited on a ceria surface are prepared experimentally or created theoretically and investigated. In this talk, recent results on ceria-supported Ni, Co and Cu model catalysts will be discussed, as examples of catalysts for DRM.1-3 The emphasis is here put on theoretical studies in combination with experiments using ambient pressure X-ray photoelectron spectroscopy, and special attention is given to the effects of ceria as catalyst support. The ability of ceria to stabilize oxidized species (MOx: Co2+ and Ni2+) on the CeO2 surface, by relocalizing electrons on localized f-states, and metal-lic ones (Co0, Ni0) on the reduced CeO2-x support, is essential for CH4 activation ?that occur at tem-peratures as low as 300 K? and its reforming at relatively low temperatures (~700 K). Also, the Ni/ceria system is considered for H2O activation and methanol synthesis from methane and wa-ter.4,5

  23. Condensed-Matter Physics & Materials Science Seminar

    "Novel Electrochemistry for Fuel Cell Reactions: Efficient Synthesis and New Characterization Methods"

    Presented by Zhixiu Liang

    Wednesday, February 6, 2019, 4:30 pm
    Bldg. 480 Conference Room

    Hosted by: Jing Tao

    The ever increasing consumption of fossil fuels for transportation causes climate change causing a growing concern about their future availability and further adverse environmental effects. To address this issue, the concept of CO2 neutral fuels-based energy cycle was brought out. The key reactions in that concept are electrochemical methanol oxidation (MOR), ethanol oxidation reaction (EOR), and CO2 reduction reaction (CO2RR). These all are elctrocatalysis research challenges being slow even at the best catalyst that hamper application of fuel cells, and bring environmental benefits. My research made these improvements of catalysts for the key reactions. In-situ electrochemical infrared reflective absorbance spectrum (EC-IRRAS) reveals that at lower temperature, such reaction is not complete and generates more formate; at elevated temperature, such reaction is complete to carbonate. Ethanol is one of the ideal fuels for fuel cells, but requires highly improved catalysts. Au@PtIr/C catalyst was synthesized with a surfactant-free wet-chemistry approach. Transmission electron microscope (TEM) characterization confirms the monolayer/sub-monolayer Pt-Ir shell, gold core structure. The catalyst has a very high mass activity of 58 A/mg at peak current. In situ EC-IRRAS reveals that C-C bond is cleaved upon contact with the catalyst surface leading to ethanol complete oxidation to CO2. Related researches on methodologies, included in situ TEM to help obtaining catalysts improvements, give morphologic, structural and spectroscopic information at wide range from hundreds of microns to sub-nanometer coupled with various detectors. Microelectromechanical System (MEMS) based chips technology enables TEM observation in operando, with liquid-flow-cell chips and electrochemistry chips designed and fabricated. Ag@Au hollow cubes synthesis via galvanic replacement of Au on Ag cubes was investigated with in situ TEM. The results demonstrate abnormal react

  24. Symposium on the 60th Anniversary of the Life-Saving Technetium-99m

    Wednesday, November 7, 2018, 3 pm
    Hamilton Seminar Room, Bldg. 555

    Speakers will present talks on technetium and nuclear medicine, including the history of the development of the Tc-99m generator at Brookhaven. The talks will be followed by a reception in the Chemistry Lobby.

  25. Chemistry Department Seminar

    "Synchrotron-based X-ray Absorption Spectroscopy for In Situ and Operando Studies of Nanoporous Catalysts"

    Presented by Kirill A. Lomachenko, European Synchrotron Radiation Facility (ESRF), Grenoble, France, France

    Monday, November 5, 2018, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Anatoly Frenkel

    X-ray absorption spectroscopy (XAS) has proven to be a very powerful tool for rationalization of catalytic processes because of the possibility to determine oxidation state and coordination geometry of catalytically active species in operando regime. The seminar will be focused on the advanced facilities for chemical XAS studies available at BM23 and ID24 beamlines of the ESRF synchrotron, which allow to exploit simultaneously a wide range of complementary techniques, make use of flexible sample environment, and obtain high-quality data in the timescale from minutes down to milliseconds. As a case study, recent work on the investigation of the local environment and electronic structure of the active centers of Cu-zeolites in deNOx and methane-to-methanol processes will be discussed.

  26. NSLS-II Friday Lunchtime Seminar

    "Materials Tribology: An Application-Driven Field with Rich Opportunities for Fundamental Studies of Surface Chemistry, Physics, Structure"

    Presented by Brandon A. Krick, Department of Mechanical Engineering and Mechanics, Lehigh University

    Friday, November 2, 2018, 12 pm
    NSLS-II Bldg. 743 Rm 156

    Hosted by: Ignace Jarrige

    The significant economic (~3-6% of developed countries GDP) and environmental (several percent of our annual energy consumption) impacts of friction and wear make tribology is an important, application-driven field. However, there is an opportunity and need for inherently fundamental studies on surface chemistry, physics and structure to elucidate fundamental mechanisms for friction and wear. The non-equilibrium and transient nature of shear-induced changes caused by contacting surfaces in relative motion requires both in situ and ex situ advanced characterization techniques; many of these only available at the light source at Brookhaven. A brief overview of shear-induced (sliding friction/wear) alterations of surfaces will be presented for material systems including: - environmental and tribochemistry molybdenum disulphide based coatings for space applications - shear-induced band bending in GaN - mechanochemistry of polymer nanocomposites

  27. Chemistry Department Seminar

    ""Size control of supported metals for catalysis""

    Presented by Xiao Yan Liu, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China), China

    Tuesday, October 30, 2018, 11 am
    Room 300 - 3rd Flr. Chemistry Bldg. 555

    Hosted by: Sanjaya Senanayake

    Catalysis by supported metals is size sensitive, so the size control is extremely important. Here, I will present two examples for the size control of catalysis. One is the size control of gold catalysts by tuning the metal support interaction. In the last decade, we've developed several methods to control the particle size of gold, for example, adding a second metal to form alloy with gold, using the thiolated gold nanoclusters as the precursor of gold catalysts, and so on. The other example focuses on single-atom catalysis that has emerged as a new frontier in heterogeneous catalysis and shown distinctive performances in a series of oxidation and hydrogenation reactions. The ways we developed to stabilize the single atoms will be introduced. The mechanism for the stabilization of the nanoparticles/single atoms were proposed based on the characterization by aberration-corrected HAADF-STEM, in situ EXAFS and DFT calculations.

  28. PubSci at the Parrish

    "Illumination: Revealing the Secret Chemistry of Oil Paintings"

    Friday, September 21, 2018, 7 pm
    Parrish Art Museum 279 Montauk Hwy., Water Mill, N

  29. Chemistry Department Colloquium

    "Proton-Coupled Electron Transfer in Catalysis and Energy Conversion"

    Presented by Dr. Sharon Hammes-Schiffer, Department of Chemistry, Yale University

    Monday, September 10, 2018, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Mehmed Zahid Ertem

    Proton-coupled electron transfer (PCET) reactions play a vital role in a wide range of chemical and biological processes. This talk will focus on recent advances in the theory of PCET and applications to catalysis and energy conversion. The quantum mechanical effects of the active electrons and transferring proton, as well as the motions of the proton donor-acceptor mode and solvent or protein environment, are included in a general theoretical formulation. This formulation enables the calculation of rate constants and kinetic isotope effects for comparison to experiment. Recent extensions enable the study of heterogeneous as well as homogeneous interfacial PCET processes. Applications to PCET in molecular electrocatalysts for hydrogen production and water splitting, photoreduced zinc-oxide nanocrystals, and the Volmer reaction will be discussed. These studies have identified the thermodynamically and kinetically favorable mechanisms, as well as the role of proton relays, and are guiding the theoretical design of more effective catalysts. In addition, recent developments of theoretical approaches for simulating the ultrafast dynamics of photoinduced PCET, along with applications to solvated molecular systems and photoreceptor proteins, will be discussed.

  30. Chemistry Department Seminar

    "Synthesis of Fuels and Chemicals by Electroreduction over Copper Catalysts"

    Presented by Elizabeth J. Biddinger, The City College of New York, CUNY

    Monday, August 6, 2018, 11 am
    Room 300 - 3rd Flr. Chemistry Bldg. 555

    Hosted by: Sanjaya Senanayake

    Electrochemical synthesis methods offer opportunities to perform reactions under benign reaction conditions (at or near room temperature and pressure), use less harmful or waste-generating reaction steps, and perform selective reactions. In electroreduction reactions, externally-supplied hydrogen that is generally needed for reduction is not required. Rather, electrons, frequently paired with the electrolyte, are the reducing agents. New opportunities for utilization of electrochemical reactions exist with the emerging renewable electricity generation market. Due to the intermittent supply sources for many renewable electricity systems, excess electricity gets generated when peak generation (sunny or windy periods) does not match with demand. Electrochemical reactions can be performed at relatively low costs with this excess electricity to synthesize fuels for later use or chemicals. The work presented here will illustrate two synthesis systems via electroreduction – carbon dioxide electroreduction to hydrocarbons and furfural (a biomass-derived species) electrochemical hydrogenation and hydrogenolysis (ECH) to fuels and chemicals. Both of these reactions are performed over copper electrodes, serving as the catalysts for the system. Copper is utilized because of its unique balance between being active for the electroreduction and less active for the undesired side reaction hydrogen evolution. In CO2 electroreduction, copper is the only known metal to produce significant quantities of hydrocarbons. By tuning the morphology, the selectivity between ethylene and methane can be tuned. The results of morphological differences and the dynamic nature of copper surfaces will be discussed in terms of electrodeposition and the resulting CO2 electroreduction performance. In furfural ECH, both 2-methyl furan and furfuryl alcohol can be formed, while over many other metals 2-methyl furan is not formed. The reaction conditions for furfural ECH si

  31. Chemistry Department Seminar

    "Triggered Reversible Phase Transformation between Layered and Spinel Structure via Intercalated Hetero Species in Sodium Birnessite"

    Presented by Yong-Mook Kang, Department of Energy and Materials Engineering, Dongguk University-Seoul, Seoul, 04620, Republic of Korea., Korea, Republic of (South)

    Monday, July 23, 2018, 11 am
    Room 300, 3rd Flr. Chemistry Bldg. 555

    Hosted by: Xiao-Qing Yang

    Phase transformation of layered structure into spinel structure has been detrimental for most of layered oxide cathodes. Even if a lot of efforts have been made to relieve this highly irreversible phase transformation, there have been few successful results. However, we firstly observed the possibility to make this irreversible phase transformation extremely reversible by utilizing Na- birnessite (NaxMnO2•yH2O; Na-bir) as a basic structural unit, which has distinctive layered structure containing crystal water. Herein, the crystal water in the structure contributes to generating metastable spinel-like phase, which is the key factor for making this unusual reversibility happen. The reversible structural rearrangement between layered and spinel-like phases during electrochemical reaction could activate new cation sites and enhance ion diffusion with higher structural stability. This unprecedented reversible phase transformation between spinel and layered structure was deeply analyzed via combined ex situ soft and hard X-ray absorption spectroscopy (XAS) analysis with in situ X-ray diffraction (XRD). Fundamental mechanism on this reversible phase transformation was theoretically elucidated and confirmed by kinetic investigation using first-principle calculation. These results provide deep insight into novel class of intercalating materials which can deal with highly reversible framework changes, and thus it can pave an innovative way for the development of cathode materials for next- generation rechargeable batteries.

  32. Chemistry Department Colloquium

    "Turning Base Metals into Precious Metals: Nanostructured Early Transition Metal Carbides and Nitrides"

    Presented by Levi Thompson, University of Michigan, Department of Chemical Engineering,

    Monday, July 9, 2018, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Sanjaya Senanayake

    The addition of carbon and nitrogen to early transition metals like molybdenum and vanadium can result in materials with properties that are similar to those of platinum group metals (PGMs). In the mid-1970s, for example, it was discovered that tungsten carbides can catalyze hydrogenation reactions that previously were only known for PGMs, and more recently we observed that molybdenum nitrides are capable of bulk hydrogen storage like Pd. Since then, early transition metal carbides and nitrides have been investigated for a variety of reactions. This paper will describe our work to design and synthesize nanostructured early transition metal carbides and nitrides for reactions including selective hydrogenations. Our research has focused on understanding the genesis of the materials, unraveling the reaction mechanisms and determining structure-function relationships that will enable the rational design of these materials. Of particular interest are CO2 hydrogenation and ammonia synthesis, reactions for which new catalysts are needed to reduce energy consumption.

  33. Chemistry Department Seminar

    "Nanowires Devices for Emerging Energy Storage"

    Presented by Liqiang Mai, Wuhan University of Technology, China

    Friday, June 15, 2018, 11 am
    Room 300 - Third Floor - Chemistry Bldg. 555

    Hosted by: Xiao-Qing Yang

    One-dimensional nanomaterials can offer large surface area, facile strain relaxation upon cycling and efficient electron transport pathway to achieve high electrochemical performance. Hence, nanowires have attracted increasing interest in energy related fields. We designed the single nanowire electrochemical device for in situ probing the direct relationship between electrical transport, structure, and electrochemical properties of the single nanowire electrode to understand intrinsic reason of capacity fading. The results show that during the electrochemical reaction, conductivity of the nanowire electrode decreased, which limits the cycle life of the devices. We have developed a facile and high-yield strategy for the oriented formation of CNTs from metal−organic frameworks (MOFs). The appropriate graphitic N doping and the confined metal nanoparticles in CNTs both increase the densities of states near the Fermi level and reduce the work function, hence efficiently enhancing its oxygen reduction activity. Then, we fabricated a field-tuned hydrogen evolution reaction (HER) device with an individual MoS2 nanosheet to explore the impact of field effect on catalysis. In addition, we demonstrated the critical role of structural H2O on Zn2+ intercalation into bilayer V2O5·nH2O. The results suggest that the H2O-solvated Zn2+ possesses largely reduced effective charge and thus reduced electrostatic interactions with the V2O5 framework, effectively promoting its diffusion. We also identified the exciting electrochemical properties (including high electric conductivity, small volume change and self-preserving effect) and superior sodium storage performance of alkaline earth metal vanadates through preparing CaV4O9 nanowires. Our work presented here can inspire new thought in constructing novel one-dimensional structures and accelerate the development of energy storage applications.

  34. Chemistry Department Seminar

    "Astrochemistry in the Laboratory – Combining Theory and Experiment"

    Presented by Kelvin Lee, Harvard-Smithsonian Center for Astrophysics

    Monday, June 11, 2018, 11 am
    Room 300, 3rd Floor, Chemistry Bldg. 555

    Hosted by: Greg Hall

    Brief overview of the laboratory and theoretical efforts in astrochemistry at the Harvard Smithsonian Center for Astrophysics. Will highlight one of our areas of research – the characterization and spectroscopy of molecular isomers in space by showcasing two recent projects (1) the rotational spectroscopy of ethynethiol (HCCSH), a higher energy isomer of thioketene, and (2) the first-principles high accuracy chemical network we are developing for the production and destruction of hydrogen (iso)cyanide in space.

  35. Chemistry Department Colloquium

    "Discovering Emergent Phenomena in Catalysis Through Large Scale Ab Initio Molecular Dynamics Simulations"

    Presented by Roger Rousseau, Pacific Northwest National Laboratory

    Tuesday, May 29, 2018, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Sanjaya Senanayake

    The current state of the art of electronic structure methods allows us to tackle model systems on the order of 100s to 1000s of atoms with suitable speed and efficiency to perform statistical mechanical sampling on millions of configurations. This has opened the door to using theoretical tools such as ab initio molecular dynamics (AIMD) combined with enhanced sampling techniques) to discover novel emergent phenomena that result from chemical complexity. Nowhere is this more needed than in catalysis, where models need to include support materials, the catalysts, the reactants and products all at elevated temperature and pressures. In this context, both global and local anharmonicities on the potential energy surface can lead to unexpected phenomena that can be discovered through large scale simulation yet are often not accounted for in current theoretical studies. This will be illustrated with examples drawn from the chemistry of metal particles on reducible supports [1-3], Brønsted acid chemistry in confined spaces [4] and reactivity at solid-liquid interfaces [5,6]. In the context of metal particles supported on reducible metal oxides (such as TiO2, CeO2 and RuO2), we have found that there is a strong coupling between the redox state of the support and the redox properties of the nanoparticle [1,2] such that unique catalytic processes can occur including: Redox state dependent reaction energies [2,3]; Formation of transient single atoms, which are themselves catalytic [1,3]; For prototypical reactions such as CO oxidation, a complex mechanistic landscape where catalysis can occur by competing mechanisms involving both the nanoparticle and single atom sites at the same time. Similar methods have been used to investigate the confinement effect in zeolite [4] and understand the free energetics of acid catalysis in confined media. It is shown that due to the large anharmonic effects associated with molecules, such as ethanol, interacting with the walls of a s

  36. HET/RIKEN Lunch Seminar

    "Quantum Simulation from Quantum Chemistry to Quantum Chromodynamics"

    Presented by Peter Love, Tufts

    Thursday, May 10, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Mattia Bruno and Enrico Rinaldi

    Quantum simulation proposes to use future quantum computers to calculate properties of quantum systems. In the context of chemistry, the target is the electronic structure problem: determination of the electronic energy given the nuclear coordinates of a molecule. Since 2006 we have been studying quantum approaches to quantum chemical problems, and such approaches must face the challenges of high, but fixed, precision requirements, and fermion antisymmetry. I will describe several algorithmic developments in this area including improvements upon the Jordan Wigner transformation, alternatives to phase estimation, adiabatic quantum computing approaches to the electronic structure problem, methods based on sparse Hamiltonian simulation techniques and the potential for experiments realizing these algorithms in the near future. I will also briefly review work by others on the analog and digital simulation of lattice gauge theories using quantum simulators.

  37. Condensed-Matter Physics & Materials Science Seminar

    "Chemistry beyond the crystal- advanced Fourier techniques"

    Presented by Simon Kimber, Oak Ridge National Laboratory

    Monday, April 30, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Ian Robinson

    Chemical crystallography nowadays makes structure determination and refinement trivial. However, advances in x-ray and neutron sources mean that we should revisit some of the basic assumptions that shape our experiments. For example, most chemical reactivity in e.g. catalysis, self-assembly etc, occurs in the solution phase. Why are we as crystallographers then wedded to the solid state? In this presentation, I will show how total scattering can be used to determine changes in cluster structure during photochemical reactions and to probe the role of the solvent in 'magic size' cluster formation. I will then describe how neutron scattering techniques can be used to challenge another basic assumption- the static approximation in total scattering. We have successfully applied so-called 'dynamic-PDF' techniques to simple chalcogenide materials. This allows to determine the time scale on which local distortions appear, providing insight into the role of highly anharmonic phonons in e.g. phase change and thermoelectric materials. Time allowing, I will also provide a short update on progress at ORNL, including the upcoming restart of the SNS, and new instrumentation for diffraction, total and diffuse scattering.

  38. Chemistry Department Seminar

    "Spectroscopy and Diabatization: Turning the GMH Method Upside Down to Study Butadiene"

    Presented by Robert Cave, Harvey Mudd College

    Friday, April 27, 2018, 11 am
    Room 300, 3rd Floor, Chemistry Bldg. 555

    Hosted by: John Miller

    The spectroscopy of the low-lying singlet states of butadiene has been a vexing problem for theorists for over forty years. The positions of the lowest-lying singlet states at the ground state geometry are something of a methodological Rorschach test and the planar stationary points of these states have seen modest attention. Important work has been done on the ultrafast dynamics of butadiene following excitation to the bright 11Bu but these studies are often forced to use simple wavefunctions that may lead to exaggerated couplings. We present new simulation results of its electronic spectrum based on Equations of Motion Coupled Cluster Theory in large basis sets using a vibronic coupling model involving many vibrational modes. We investigate the sensitivity of the results to the choice of vibronically-coupled states and test the dependence of the results on vertical excitation energies. We believe that butadiene should be considered somewhat less vexing than it has been before and our results can be used as a starting point for accurate explorations of its short-time excited state dynamics.

  39. Center for Functional Nanomaterials Seminar

    "Electrocatalysis: From nanoelectrochemistry to materials design"

    Presented by Professor Dr. Wolfgang Schuhmann, Ruhr-Universität Bochum, Analytical Chemistry and Center for Electrochemical Sciences (CES), Germany

    Friday, April 27, 2018, 11 am
    Bldg 735, CFN, Seminar Room 2nd Floor

    Hosted by: Huolin Xin

  40. Chemistry Department Seminar

    "In situ analysis of Ru-based catalysts under water oxidation conditions"

    Presented by Yulia Pushkar, Purdue University

    Tuesday, February 27, 2018, 10 am
    Room 300, 3rd Floor, Chemistry Bldg. 555

    Hosted by: Dmitry Polyansky

    Realization of artificial photosynthesis carries the promise of cheap and abundant energy. The water molecule is an ideal source of electrons and protons for fuel forming reactions, but the chemical complexity of water splitting makes practical realization challenging. To advance the catalyst's rational design, detailed information on the structure of the catalyst under reaction conditions and mechanisms of O-O bond formation are required. Here, we used a combination of EPR, freeze quench and stopped flow spectroscopy with ms-s time resolution, X-ray absorption spectroscopy (XAS), Resonance Raman (RR) and DFT to follow in situ catalyst dynamic under conditions of water oxidation.1-3 Two representative Ru –based catalysts were analyzed: [RuII(NPM)(4-pic)2(H2O)]2+ and [RuII(pic)2(dpp)]2+. First system has water coordinated to Ru center and forms [RuIV(NPM)(4-pic)2=O]2+ upon oxidation. This intermediate undergoes fast dynamics (on few sec time scale) of oxygen atom transfer from the RuIV=O oxo species to uncoordinated nitrogen of the NPM ligand. NPM ligand modification occurs on the time scale of catalyst activation and results in [RuIII(NPM-NO)(4-pic)2(H2O)]3+ and [RuIII(NPM-NO,NO)(4-pic)2]3+ complexes with unique EPR signals. [RuII(pic)2(dpp)]2+ complex was proposed to activate via formation of the 7-coordinate [RuV=O(pic)2(dpp)]3+ species. We report the first detection of the ligand protected 7-coordinate species in catalytic mixtures by combination of the spectroscopic techniques. Over a few minutes this intermediate transfers oxygen from the RuV=O group to a pyridyl nitrogen of the dpp ligand. This reaction proceeds twice resulting in the dpp-di-N-oxide ligand. This ligand modification results in the catalyst activation. [Ru(bda)(pic)2] complex is also proposed to activate via formation of 7-coordinate [RuV=O(bda)(pic)2]+ intermediate which is highly reactive in solution via radical coupling pathway. Site isolation of the catalyst on the electrode

  41. NSLS-II Friday Lunchtime Seminar Series

    "Using X-ray Fluorescence Microprobe to Elucidate the Chemistry of Trace Elements in Soils and Plants"

    Presented by Ryan Tappero, NSLS-II

    Friday, February 23, 2018, 12 pm
    NSLS-II Bldg. 743 Rm 156

    Hosted by: M. Abeykoon, S. Chodankar, B. Ocko, T. Tanabe, J. Thieme

  42. Chemistry Department Seminar

    "Learning the nanocatalyst structure "on the fly" using neural networks"

    Presented by Dr. Janis Timoshenko, Dept. of Material Science and Chemical Engineering, Stony Brook University

    Monday, February 12, 2018, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Sanjaya Senanayake

    Understanding of atomic structure in metallic nanoparticles (NPs) and its relation to the NPs properties is important for design of novel catalytic materials. In-situ studies are an essential element in such investigations, since the atomic structure of nanosized catalysts can change dramatically in reaction conditions. X-ray absorption spectroscopy is one of a few methods that are useful in this case, due to its sensitivity to the chemical state of absorbing atoms and to the types and arrangements of atoms around the absorber, and its suitability for in-situ and in-operando studies. While EXAFS spectroscopy is widely used in NPs structure studies, much less attention has been paid to the information encoded in X-ray absorption near edge structure (XANES). Analysis of XANES data has several advantages. First, XANES is less sensitive to disorder, which affects severely EXAFS quality and complicates EXAFS data interpretation. Secondly, XANES is more sensitive to the 3D geometry of the environment around absorbing atoms. Better signal-to-noise ratio in XANES region of absorption spectra also means that spectra can be collected with better time-resolution, for more diluted samples, on strongly attenuating support materials and/or in complex experimental setups. The main challenge that hinders the usage of XANES for quantitative analysis is the lack of methodology that would allow one to extract structural information from experimental data. Recent developments in data-enabled discovery methods provide a key to this problem. To correlate XANES features with the descriptors of 3D local structure of metallic NPs, we employed machine learning and ab-initio XANES calculations. Here we demonstrate the potentiality of this method on the example of XANES study of monometallic (Pt, Ag and Cu), as well as bimetallic (PdAu) particles. We use theoretical site-specific XANES spectra, calculated by ab-initio codes for a broad range of structure models, to train an artificial neura

  43. Chemistry Department Seminar

    "In situ Studies and Gas Phase Visulation of Model Catalysts at Work"

    Presented by Prof. Edvin Lundgren, Institute of Physics, Lund University, Sweden

    Wednesday, January 31, 2018, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Sanjaya Senanayake

    Motivated mainly by catalysis, gas-surface interaction between single crystal surfaces and molecules has been studied for decades. Most studies have been performed in well-controlled environments, and has been instrumental for the present day understanding of catalysis. We have for some years explored the possibilities to perform experiments at conditions closer to those of a technical catalyst, in particular at increased pressures. In this contribution we will show examples from catalytic CO oxidation over Pd single crystal surfaces using Ambient Pressure X-ray Photo emission Spectroscopy (APXPS) [1] and High Energy Surface X-Ray Diffraction (HESXRD) [2] at more realistic conditions. However, the detected surface structure during the reaction is sensitive to the composition of the gas phase close to the catalyst surface [3-4]. Therefore, the catalytic activity of the sample will itself affect the surface structure, which may complicate the assignment of the active phase. For this reason, we have applied 2D Planar Laser Induced Fluorescence (PLIF) to the gas phase in the vicinity of an active model catalysts [5-7]. In particular, these measurements enables a direct view of the onset and location of the catalytic activity. Further, the gas phase distribution during a catalytic reaction from more complicated samples, such as a curved single crystal upon ignition [8] may be explored, see Fig. 1. [1] S. Blomberg et al; Phys. Rev. Lett. 110, 117601 (2013). [2] J. Gustafson et al; Science, 343, 758 (2014). [3] S. Matera and K. Reuter, Phys. Rev. B 82, (2010) 085446. [4] S. Matera et al; ACS Catalysis 5, 4514 (2015). [5] J. Zetterberg et al; Rev.Sci. Instrum. 83, 053104 (2012). [6] J. Zetterberg et al; Nat. Comm. 6, 7076 (2015). [7] S. Blomberg et al; ACS catalysis 5, 2028 (2015). [8] S. Blomberg et al; ACS Catalysis 7, 110 (2016).

  44. Chemistry Department Seminar

    "Methane reforming with CO2 over Ni-Co/CeZrO2 catalysts"

    Presented by Dr. Petar Djinovic, Department for Environmental Sciences and Engineering, Slovenia

    Tuesday, November 28, 2017, 11 am
    Chemistry Bldg, 555, Room 300

    Hosted by: Dr. Jose Rodriguez

    Methane reforming with CO2 presents a possible pathway for valorization of natural gas or biogas to syngas (H2 and CO). Transition metal catalysts suffer from fast deactivation, mainly due to carbon accumulation. This lecture will focus on systematic development of bimetallic NiCo catalysts dispersed over CeZrO2 supports with the final realized aim of enabling long-term stable operation in a wide range of feed compositions. The role of bimetallic cluster size and amount of labile oxygen species in the CeZrO2 support on preventing the carbon accumulation will be discussed. Catalytic tests with isotopically labeled 13CO2, enabled us to identify the contribution of each reactant to the accumulated carbon pool and to distinguish between their reactivity. By replacing lattice oxygen contained in NiCo/CeZrO2 catalysts with isotopically labelled 18O, we were able to monitor transient changes of the catalyst's behavior during methane dry reforming reaction and identify the destination of lattice oxygen in the reaction products.

  45. Chemistry Department Seminar

    "Ambient Pressure XPS as a Tool to Probe Metal-Oxide Catalyst Behaviour"

    Presented by David Grinter, Diamond Light Source Ltd, Diamond House, Harwell Science & Innovation Campus, Didcot, Oxfordshire

    Monday, November 13, 2017, 11 am
    Room 300 - Chemistry Bldg. 555

    Hosted by: Sanjaya Senanayake

    Ambient Pressure X-ray Photoelectron Spectroscopy (AP-XPS) has provided numerous important insights into the behaviour of materials under conditions out of reach of traditional surface science experiments. In the first part of this talk I will highlight the application of AP-XPS to a number of model heterogeneous catalyst systems based on TiO2 and CeO2. Catalysts composed of metal-oxide supported nanoparticles have wide ranging industrial uses with particular energy-related applications including alternative fuel synthesis. I will demonstrate how AP-XPS plays a vital role as part of a multi-technique approach into investigating the reactions that occur at the surface of such materials. Figure 1. Cartoon depiction of the interrogation of a model supported catalyst by AP-XPS, and C1s AP-XPS spectra from a Ni/CeO2 catalyst under methane dry reforming conditions. The second part of my talk will cover the development and recent science commissioning experiments at the newest beamline at Diamond Light Source (UK) – B07 VERSOX (Versatile Soft X-ray). The VERSOX beamline is designed to provide synchrotron radiation soft X-rays between 50 and 2800 eV for studying atomic structures and the electronic/chemical properties of surfaces and interfaces by Photoelectron Spectroscopy (XPS) and Near-Edge X-ray Absorption Spectroscopy (NEXAFS) under wide-ranging pressures (10-10 to 1000 mbar) and temperatures (100-1200 K). The beamline is designed to have separate sources and optical components that will allow independent and parallel operation of two soft X-ray branch lines; B07-C (Ambient Pressure) and B07-B (High Throughput). Figure 2. Beamline layout of B07 VERSOX, and C K-edge XAS spectra from a diamond (001) surface

  46. Chemistry Department Colloquium

    "Can Coherence Enhance Function in Chemical and Biophysical Systems?"

    Presented by Professor Gregory D. Scholes, Dept. of Chemistry, Princeton University

    Monday, September 25, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Matt Bird

    Coherence phenomena arise from interference, or the addition, of wave-like amplitudes in phase. While coherence has been shown to yield transformative new ways for improving function, advances have been limited to pristine matter, as quantum coherence is considered fragile. Recent evidence of coherence in chemical and biological systems, however, concludes that the phenomena is robust and can survive in the face of disorder and noise. I will present the state of recent discoveries. For example, two-dimensional electronic spectroscopy data allow quantitative analysis of vibronic coherence in the photosynthetic light harvesting complexes [1]. I will show how vibronic coherence plays a special role in downhill energy transfer, increasing energy transfer rates remarkably—even when electronic coupling is weak [2]. I will discuss how coherence might be found in electron transfer reactions. I will conclude with a forecast for the role of function as a design element in realizing coherence [3]. [1] Scholes, et al. "Lessons from nature about solar light harvesting" Nature Chem. 3, 763–774 (2011). [2] Dean et al. "Vibronic Enhancement of Algae Light Harvesting" Chem (Cell Press) 1, 858–872 (2016). [3] Scholes, et al. "Optimal Coherence in Chemical and Biophysical Dynamics" Nature 543, 647–656 (2017).

  47. Chemistry Department Colloquium

    ""Taking Snapshots of Reaction Intermediates in Metalloenzymes and Catalysts with X-ray Techniques""

    Presented by Junko Tano, Ph.D., Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory

    Monday, September 11, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Javier Concepcion

    Our group is interested in the mechanisms of the catalytic reactions in both natural and inorganic systems. Using various X-ray techniques as tools, we are studying how the catalysts modulate and control multielectron reactions by following the reaction under functional conditions. We have developed spectroscopy and diffraction techniques necessary to fully utilize the capability of the XFELs for a wide variety of metalloenzymes, and to study their chemistry under functional conditions. One of such methods is simultaneous data collection for X-ray crystallography and X-ray spectroscopy, to determine the overall structural changes of proteins and the chemical changes at metal catalytic sites. In parallel to the detection techniques, we have developed an efficient sample delivery method that involves deposition of droplets on a conveyor belt. This 'Droplet on Tape' (DOT) method, delivers a single drop of the crystal suspension or solution sample onto a tape, which then can be transported to the X ray intersection point with a variable delay in time. In the process, the sample is photochemically or chemically activated at various time delays to capture reaction intermediates with crystallography and spectroscopy. In the field of inorganic catalysts, improved catalysts for electroreduction of carbon dioxide are highly important for promoting the generation of carbon-based reduction products. To gain a fundamental understanding needed to tailor novel catalysts, in particular for the selectivity of the products, the information of the early steps of the electroreduction process on catalyst surfaces is important. We have optimized and utilized surface-sensitive soft and hard X-ray techniques, including grazing incident X-ray absorption spectroscopy, X-ray diffraction, and ambient pressure X-ray photoemission spectroscopy to investigate the interaction of metal catalytic surfaces with electrolytes and/or gases (CO2 and/or H2O) under in situ/operando conditions.

  48. Chemistry Department Colloquium

    "Chemical Kinetics and Tunneling on Interstellar Dust Grains"

    Presented by Professor Gunnar Nyman, Dept. of Chemistry and Molecular Biology, University of Gothenburg, Goteborg, Sweden, Sweden

    Monday, August 28, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Greg Hall

    Dust can be important for the interstellar chemistry in the gas phase. The process where an atom or molecule lands on a dust grain, diffuses on the grain and meets another atom or molecule to form a new species, which can then desorb from the grain is essentially a description of how heterogeneous catalysis occurs. The importance of this process would depend on the diffusion rate of at least one of the adsorbed species and the products desorbing from the grain. This is particularly relevant for H2 formation in interstellar space. Atoms and molecules adsorbed on grains may be modeled as sitting in a local potential energy minimum. Diffusion can then be thought of as occurring through consecutive jumps from one minimum to another. The transition rate constants between adjacent minima can be estimated by for instance transition state theory. Such rate constants can in turn be used in Kinetic Monte Carlo simulation to obtain diffusion rates. Light atoms, particularly hydrogen atoms can tunnel through potential energy barriers. Tunneling may therefore substantially increase the rate of transition from one minimum to the next and thus the diffusion rate. Deuterium tunnels less efficiently than the lighter isotope and kinetic isotope effects (KIEs) are thus expected. Laboratory experiments have been carried out where either H atoms or D atoms diffuse on amorphous or polycrystalline ice at 10 K. Interesting KIEs were obtained.

  49. Nuclear Theory/RIKEN Seminar

    "Better fitting through (fictitious) chemistry"

    Presented by Pasi Huovinen, Uniwersytet Wroclawski

    Monday, June 19, 2017, 10 am
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    One of the puzzles we have faced at the LHC is why the thermal models apparently cannot properly fit the yield of protons. I will explore how the fit improves if we assume that nucleon-antinucleon annihilations freeze-out way later than all other number changing processes or if strange particles freeze-out before non-strange particles, and how this affects the final particle distributions in hydrodynamical calculations.

  50. Chemistry Department Seminar

    "Modeling of the synergistic behavior of adjacent Pt{111}"

    Presented by Thobani Gambu, Catalysis Institute, Department of Chemical Engineering,, South Africa

    Wednesday, June 14, 2017, 4 pm
    Room 300 - Chemistry Bldg. 555

    Hosted by: Miomir Vukmirovic

    Abstract The oxygen reduction reaction (ORR) is particularly interesting, especially in the context of fuel cells and metal-air batteries [1,2]. The loss in cell potential at low current densities accounts for over 67% of the total potential loss and is primarily attributed to slow ORR kinetics [3]. When modelling the overall ORR activity over multifaceted Pt nanocrystallites, it is generally assumed that the different surface regions, i.e. terraces, edges and corners, are kinetically isolated and can therefore be modelled independently [4-5]. A range of ORR mechanisms have been proposed and the corresponding energetics, i.e. reaction and activation energies, have been calculated and reported [6-8]. A closer look at the reaction mechanisms and energetics shows that (1) O and OH removal over a Pt(111) and Pt(100) surface, respectively, is the most energetically hindered step, [6-8] and (2) facilitating an OH/O exchange between the Pt{111} and Pt{100} facets may result in improved ORR specific activity. Therefore, this study investigates the extent of O and OH cross-surface diffusion between the Pt{111} and Pt{100} facets of a pure Pt nanorod model. Furthermore, the cross-surface diffusion of OH on modified Pt nanorod models is reported. References 1. Gewirth, A. A. and Thorum, M. S. Inorg. Chem. 49, 3557 (2010). 2. Nie, Y., Li, L. and Wei, Z. Chem. Soc. Rev. 44, 2168 (2015). 3. Gasteiger, H. A., Kocha, S. S. et al. Appl. Catal. B Environ. 56, 9 (2005). 4. Tripkovic, V., Cerri, I. et al. Catal. Letters. 144, 380 (2014). 5. Nesselberger, M., Ashton, S. et al. J. Am. Chem. Soc. 133, 17428 (2011). 6. Li, K., Li, Y. et al. J. Mater. Chem. A. 3, 11444 (2015). 7. Duan, Z. and Wang, G. J. Phys. Chem. C. 117, 6284 (2013). 8. Ford, D. C., Nilekar, A. U. et al. Surf. Sci. 604, 1565 (2010).

  51. CFN Colloquium

    "Materials Chemistry via Electrochemistry: Electrochemical Synthesis of Semiconductor Electrodes and Catalysts for Use in Solar Energy Conversion"

    Presented by Kyoung-Shin Choi, Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53796

    Thursday, June 1, 2017, 4 pm
    CFN, Bldg 735, 2nd Floor Seminar Room

    Hosted by: Mingzhao Lu

    Harvesting energy directly from sunlight as nature accomplishes through photosynthesis is a very attractive and desirable way to solve the energy challenge. Many efforts have been made to find appropriate materials and systems that can utilize solar energy to produce chemical fuels. One of the most viable options is the construction of a photoelectrochemical cell that can directly utilize solar energy to drive chemical reactions (e.g. reduction of water to H2, reduction of CO2 to carbon-based molecules). For successful construction of photoelectrochemical cells, simultaneous developments of photoelectrodes, which will efficiently capture photons to generate and separate electron-hole pairs, and catalysts, which will facilitate the use of photogenerated electrons and holes for desired interfacial charge transfer reactions, are necessary. Furthermore, optimally interfacing photoelectrodes and catalysts is critical because the photoelectrode/catalyst interface can govern the overall efficiency of the integrated photoelectrode system. Our research group has been developing new electrochemical synthesis conditions to produce semiconductor electrodes and catalysts with precisely controlled compositions and architectures. In this seminar, we will discuss synthesis and properties of a few promising photoelectrode and catalyst systems for use in solar energy conversion. New synthesis strategies to improve photon absorption, charge transport properties, and catalytic properties will be presented. We will also discuss various strategies to increase the overall utility and efficiency of the photoelectrochemical cells, which include our new results on electrochemical and photoelectrochemical biomass conversion.

  52. Chemistry Department Colloquium

    "Adsorption and oxidation reactions on RuO2 and IrO2 surfaces"

    Presented by Jason F. Weaver, University of Florida, Dept. of Chemical Engineering

    Tuesday, May 30, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Sanjaya Senanayake

    Interest in the surface chemistry of late transition-metal oxides has been stimulated by observations that the formation of metal oxide layers tends to dramatically alter the catalytic performance of transition metals in applications of oxidation catalysis. In this talk, I will discuss our recent investigations of the growth and chemical properties of rutile RuO2 and IrO2 surfaces. Our interest in these oxides derives mainly from computational predictions that CH4 binds strongly and should undergo C-H bond activation at low temperature on certain facets of IrO2. I will discuss our investigations of the oxidation of metallic Ir surfaces by O-atom beams as well as O2 at pressures above 1 Torr. We find that stoichiometrically-terminated IrO2(110) layers could only be formed by oxidizing Ir(111) and Ir(100) at sufficiently high temperature and O2 pressure. I will discuss the binding characteristics of small molecules, and our recent discovery of highly facile CH4 activation on the IrO2(110) surface at temperatures as low as 150 K. We show that CH4 activation occurs by a mechanism wherein a molecularly-adsorbed ?-complex serves as the precursor for CH4 dissociation on the IrO2(110) surface and that the barrier for C-H bond cleavage is nearly 10 kJ/mol less than the molecular binding energy. Lastly, I will discuss results showing how the partial replacement of surface O-atoms with Cl-atoms alters the oxidation chemistry of methanol on RuO2(110), and may provide an approach for modifying the selectivity of RuO2 and IrO2 surfaces for other oxidation chemistries.

  53. Chemistry Department Colloquium

    "Electrocatalysts for Oxygen Reduction Reaction"

    Presented by Minhua Shao, The Hong Kong University of Science and Technology, Department of Chemical and Biomolecular Engineering, Hong Kong

    Friday, May 26, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Alex Harris

    Low temperature fuel cells are electrochemical devices that convert chemical energy directly to electricity. They have great potential for both stationary and transportation applications and are expected to help address the energy and environmental problems that have become prevalent in our society. Despite their great promise, commercialization has been hindered by lower than predicted efficiencies and high loading of Pt-based electrocatalysts in the electrodes. For more than five decades, extensive work has being focused on the development of novel electrocatalysts for fuel cell reactions. In this talk, I will present recent progress in developing advanced electrocatalysts mainly for oxygen reduction reaction in my group, with an emphasis on core-shell and shape controlled nanocrystals. Fuel cell testing results on these advanced catalysts will be shared. The mechanisms for activity enhancement will also be discussed based on the results of density functional theory calculations.

  54. Computational Science Initiative Event

    "Enabling Computational Chemistry With New Algorithms on Next-Generation Platform"

    Presented by Wibe deJong, Lawrence Berkeley Nat. Lab

    Monday, May 8, 2017, 11 am
    Seminar Room, Bldg. 725

    Hosted by: Kerstin Kleese van Dam

    With the advent of exascale computing the field of computational chemistry is on the verge of entering a new era of modeling. Large computing resources can enable researchers to tackle scientific problems that are larger and more realistic than ever before, and to include more of the complex dynamical behavior of nature. However, the future exascale architectures will be significantly different and require advances in algorithms and new programming paradigms. We will discuss some of the work on developing scalable algorithms for strongly correlated systems, simulations of complexes in dynamical environments, and complex spectra. Significant improvements will be reported in our development efforts of a full threaded plane wave ab initio molecular dynamics code in NWChem on Intel Phi platforms. Finally, we will demonstrate advances in the parallel communication layer Global Arrays utlizing LBNL's GasNET and barrier elision techniques. Bio: Bert de Jong leads the Computational Chemistry, Materials, and Climate Group at LBNL. He has a background in general chemistry, chemical engineering and high performance computational chemistry, with specialization and strong capabilities in modeling heavy element chemistry. He is a main developer of the NWChem software at the EMSL, one of four developers of the unique fully relativistic software MOLFDIR for quantum chemistry. Prior to joining Berkeley Lab, de Jong was at PNNL, where he lead the High Performance Software Development Group responsible for NWChem. He has published 89 journal papers, 14 conference papers and 7 book chapters and has given over 65 invited presentations and lectures at international conferences and universities.De Jong earned his doctorate in theoretical chemistry in 1998 from the University of Groningen in the Netherlands. He was a postdoctoral fellow at PNNL before transitioning to a staff member in 2000.

  55. Chemistry Department Seminar

    "The Representation of Photosynthesis in Earth System Models"

    Presented by Alistair Rogers, Department of Environmental & Climate Sciences, Brookhaven National Laboratory

    Monday, May 1, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Sanjaya Senanayake

    The primary goal of Earth System Models is to improve understanding and projection of global change which is driven principally by the elevation of atmospheric carbon dioxide concentration resulting from the use of fossil energy. Many of the observed and projected impacts of global change portend increasing environmental and economic risk, yet the uncertainty surrounding the projection of our future climate remains unacceptably high. Although annual carbon dioxide emissions associated with anthropogenic activity are notable, they are a fraction of the size of the carbon fluxes associated with the global carbon cycle. Terrestrial photosynthesis (gross primary productivity) is the largest of these carbon fluxes and is the gatekeeper process for the uncertain subsidy of fossil fuel use provided by the terrestrial carbon sink. Therefore, increasing confidence in model representation of photosynthesis - particularly the response of photosynthesis to rising carbon dioxide concentration and temperature - is an essential part of reducing uncertainty in projections of global change. Focusing on leaf level physiology, I will discuss the how parametric and structural representation of photosynthesis impacts model responses to key environmental drivers and show how data from recent field work in the Arctic and the tropics is aiming to inform model parameterization and representation of photosynthesis in next generation models.

  56. Chemistry Department Colloquium

    "Designing Catalysts Using Atomic Layer Deposition"

    Presented by Stacey F. Bent, Stanford University, Department of Chemical Engineering

    Wednesday, April 26, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Alex Harris

    With the intensifying global need for alternative energy and fuels, there is strong interest in the development of efficient catalysts that can drive the chemical conversion of renewable resources into useful products. This talk will describe the use of an emerging synthetic strategy, atomic layer deposition (ALD), to generate nanoscale catalyst materials with a high level of control over composition, structure, and thickness. Two catalytic applications will be described. The first example is the conversion of synthesis gas (CO + H2) to synthetic liquid fuels and high-value chemicals using supported metal, heterogeneous catalysts. The promotion of rhodium-based catalysts, which have intrinsic selectivity towards desirable higher oxygenate production, is explored using various metal oxides deposited by ALD. The interactions between catalyst and promoter are studied using a variety of experimental techniques complemented by theory and the promoted catalysts are shown to have an increase in activity and higher oxygenate selectivity relative to unpromoted Rh nanoparticles. The second application is electrocatalysis for water splitting to produce hydrogen for fuel. We show that nanometer thick electrocatalyst layers of earth abundant materials deposited by ALD are active for the oxygen evolution reaction, an important reaction in the conversion of sunlight to fuels. We also demonstrate use of this layer-by-layer synthetic strategy to explore other metal oxides for electrocatalysis, to study charge transport limitations in the catalysts, and to achieve compositional control over ternary metal oxide and doped metal oxide thin films. The potential of atomic layer deposition to synthesize nanoscale materials for catalytic applications will be discussed.

  57. Chemistry Department Seminar

    "Experimental and computational approaches to divine gene function in plants"

    Presented by Dr. Ian Blaby, Brookhaven National Laboratory, Biology Department

    Monday, April 17, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Sanjaya Senanayake

    The availability of whole-genome sequences has ushered in a new era of biological research. While these resources are invaluable, the data serve to underscore the extent of biological complexity, and have provided the framework by which our lack of knowledge and progress can be measured. For instance, even in very well studied model organisms, over 40% of genes are of unknown function. In less characterized complex organisms, such as bioenergy crops, up to 80% of all genes in a given genome are of unknown or very limited function. Indeed, a complete functional understanding (i.e. combined knowledge of biochemical activity, biological role and compartmentalization) is missing for ~95% of plant genes. This fundamental knowledge gap undermines the ability of systems scientists to realize the potential of genomic science and impedes our ability to leverage photosynthetic organisms to meet national energy needs. To remove this obstacle, we are addressing the function of plant proteins at the cellular and subcellular levels by integrating multi-dimensional dataypes: in vivo analyses employing single-celled plants and photosynthetic bacteria, high-throughput automation, in vitro protein characterization and structure, and computation. Modern sequencing, functional genomics and genome-editing technologies coupled with high-throughput approaches accelerate the gathering of informative data; our group specializes in utilizing multi-sourced data types in combination with targeted molecular approaches to reduce the knowledge gap in foundational plant research.

  58. Chemistry Department Colloquium

    "Excitons, Charge-Transfer states, Charge-Separated states, and Carriers: the importance of charge delocalization"

    Presented by Dr. Garry Rumbles, National Renewable Energy Laboratory, Golden Colorado

    Friday, April 7, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Alex Harris

    Although organic photovoltaic (OPV) devices have increased in solar harvesting efficiency, there remains much debate surrounding the mechanism by which the active medium absorbs solar radiation and creates high yields of free, mobile carriers that do not immediately recombine. The uncertainty arises from the low dielectric constant of the active material, normally a conjugated polymer and a fullerene, which lack the ability to screen the coulombic interaction between charges. This presentation will discuss the role of charge delocalization on producing a charge-separated state, where the electron and hole are created at a larger distance than that found in a charge- transfer state. It will examine the important role of the solid-state microstructure of the polymer and its impact on delocalizing the hole, and also on the aggregation properties of the electron acceptor and its role on delocalizing the electrons. In addition, the role that time-resolved microwave conductivity (fp-TRMC) plays in helping to unravel this story will be explained.

  59. Chemistry Department Seminar

    "Reactions of the Simplest Criegee Intermediate with Inorganic Acids and Alcohols"

    Presented by Professor Craig Murray, Department of Chemistry, University of California, Irvine

    Thursday, April 6, 2017, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Trevor Sears

    Carbonyl oxides, known as Criegee intermediates, are reactive radicals formed via alkene ozonolysis that are thought to play an important role in tropospheric chemistry, including reactions that lead to aerosol particle formation. Globally, reaction with water (or water dimer) is thought to be the major sink for formaldehyde oxide (CH2OO), while larger species tend to undergo thermal unimolecular decomposition (Osborn and Taatjes, 2015). However, reactions of CH2OO with trace atmospheric species can be locally competitive under certain conditions. We have applied broadband transient absorption spectroscopy (Foreman et al., 2015) to probe CH2OO via the B-1A′–X-1A′ transition in the near UV to directly measure rate constants for the reactions of CH2OO with inorganic acids and alcohols. Reaction with nitric acid (HNO3) in particular is exceptionally fast, indicating that it may be competitive with water in polluted urban areas, particularly under conditions of lower relative humidity and lower temperature (Foreman et al., 2016). The experimental measurements are supported by complementary ab initio that identify likely products and elucidate mechanistic details.

  60. Chemistry Department Seminar

    "How Can the Hard X-ray Spectroscopy Program Contribute to the Operando Field"

    Presented by Dr. Klaus Attenkofer, Photo Sciences - Brookhaven National Laboratory

    Monday, March 27, 2017, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Sanjaya Senanayake

    With the transition from NSLS to NSLS-II the landscape of hard x-ray spectroscopy has dramatically changed. Resulting from the needs to understand not only a material but also its behavior within a complex device structure and ultimately to demonstrate its contributions to the functional characteristics of the device, the experimental demands are driving the development of the facilities, their operation and access conditions, and their embedding in a larger characterization and computation network at NSLS-II, the laboratory, and collaborators on the national and international level. The talk will give a short overview on the status and plans of the facilities; it will also show on examples how the program focuses on specific areas in which future leadership is targeted. An important aspect of these discussions is a requirement-analysis describing the essential components allowing to use the developed tools in applied and industrial science.

  61. Chemistry Department Colloquium

    "Computational Design of Bimetallic Nanocrystals"

    Presented by Konstantin M. Neyman, Universtat de Barcelona, Spain

    Monday, March 20, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Jose Rodriguez

    Metal nanoparticles are key components of various functional materials, including catalysts. However, properties of monometallic particles are often insufficiently versatile, which limits their applications. Properties of mixed-metal nanoparticles (nanoalloys) can be tailored for a given application much easier. Yet, it is very laborious to determine the atomically resolved composition (chemical ordering) in nanoalloys, which is required for rationalizing their reactivity. We developed a method to optimize chemical ordering in nanoalloys using density functional calculations [1,2], which is applicable to various combinations of transition metals with each other and with s,p-elements [1-5]. The method allows one to predict energetically stable atomically resolved structures of nanoalloys, which can be then manufactured. I will outline the method and illustrate its applications to nanoalloys of Pd [1,2], Pt [3,4] and Ni [5]. Our new method enables generating databases of structures and energies of bimetallic nanoalloys spanning the Periodic Table. Its simplicity and reliability allows to provide researchers with unique opportunity to efficiently perform simulations of various nanoalloys with thousands of atoms. Applications of the method can radically accelerate design of tailor- made nanoalloys and deepen the general understanding of chemical bonding in nanoalloys. In the beginning of the talk I will also highlight some of my other other studies related to approaching complexity of nanomaterials for catalysis by density functional modelling [6-10]. References [1] S.M. Kozlov, G. Kovács, R. Ferrando, K.M. Neyman. How to determine accurate chemical ordering in several nanometer large bimetallic crystallites from electronic structure calculations. Chemical Science 6 (2015) 3868 [2] G. Kovács, S.M. Kozlov, K.M. Neyman. Versatile optimization of chemical ordering in bimetallic nanoparticles. J. Phys. Chem. C 121 (2017), doi: 10.1021/acs.jpcc.6b11923

  62. Center for Functional Nanomaterials Colloquium

    "Materials Chemistry of Carbon Nanomaterials and their Integration in Electronic Devices"

    Presented by George Tulevski, IBM

    Thursday, January 12, 2017, 4 pm
    CFN, Bldg 735, 2nd Floor Seminar Room

    Hosted by: Matt Sfeir

    The exceptional electronic properties of carbon nanotubes (CNTs) make them promising candidates for integration into a variety of future technologies. The key technical bottlenecks to progress on this front are mainly materials and chemistry related. How do we get the exact type of CNTs we want? How do we quantify the purity of these materials? How do we organize and place them on substrates? The solutions to these problems can enable a wide range of applications in the electronics industry. In this talk, I will present recent progress in trying to solve these problems. I will also discuss how these results have enabled the fabrication of transparent conducting electrodes (along with their integration in photovoltaic cells and OLEDs), high performance thin-film transistors on both rigid and flexible substrates and progress towards a CNT-based logic technology.

  63. Biology Department Seminar

    "Blueprints for Photosynthesis: The genetics and biochemistry of photosystem II assembly"

    Presented by Robert Calderon, University of California, Berkley

    Friday, November 18, 2016, 11 am
    John Dunn Seminar Room, Bldg. 463

    Hosted by: Ian Blaby

    Photosystem II (PSII) is the protein-pigment complex in oxygenic photosynthesis that uses light energy to catalyze the oxidation of water. How the subunits and cofactors that make up this enzyme are properly assembled into a functional photosystem remains unknown. To uncover new components in this process, I undertook a chlorophyll fluorescence-based mutant screen in the unicellular green alga Chlamydomonas reinhardtii. One isolated mutant had no detectable PSII activity, whereas other components of the photosynthetic electron transport chain were still functional. This defect was shown to be due specifically to the absence of a gene, RBD1, encoding a thylakoid membrane-bound iron-sulfur protein known as a rubredoxin. Examination of cyanobacterial (Synechocystis) and plant (Arabidopsis) mutants lacking the homolog of RBD1 revealed PSII-specific phenotypes, supporting the hypothesis that this rubredoxin has a conserved role in PSII-containing organisms. The phylogenetic profile of the RBD1 gene led us to hypothesize that other genes involved in PSII assembly or function might show a similar phylogenetic distribution. We devised a computational approach to find these genes and preliminary results indicate that some genes found through this method might indeed be associated with PSII function or assembly.

  64. PubSci

    "The Cutting Edge of Chemistry and the Reactions Powering the World"

    Tuesday, November 15, 2016, 7 pm
    Brewology Gastropub, 201 Main St., Port Jefferson,

    PubSci, a science café presented by Brookhaven National Laboratory, is back with its seventh installment of casual conversations about the Lab's world-class research. Invite your friends and colleagues to a lively discussion for the science-interested (or just plain curious) and chat with scientists in an informal and friendly way. No stuffy lectures – just a dynamic talk with a diverse audience and a lot of good cheer. Next up: "The Cutting Edge of Chemistry and the Reactions Powering the World." Join Brookhaven scientists to discuss some of the grand energy challenges of the 21st century and the role of fundamental research in energy generation. How does understanding chemical conversion help us design advanced fuels? How much energy can we squeeze out of the periodic table? How do we study catalysts in real time?

  65. Chemistry Department Colloquium

    "In Situ and Operando Electron Microscopy Imaging and Spectroscopy of Thermal and Light Driven Catalysts"

    Presented by Peter A. Crozier,, School for the Engineering of Matter, Transport and Energy,

    Friday, August 26, 2016, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Sanjaya Senanayake

    CHEMISTRY COLLOQUIUM Friday, August 26th, 2016 11:00am – Hamilton Seminar Room Chemistry Building, 555 Understanding the fundamental relationships between catalyst activity and structure at the nanoscale will enable the improved design of catalysts. In-situ and operando environmental transmission electron microscopy (ETEM) are powerful techniques for the investigation of structure-reactivity relationships in high surface area catalysts under reaction conditions. With new instruments, atomic resolution imaging and spectroscopy can be carried out in the presence of gas, liquid, light and thermal stimuli. The combination of mass spectrometry and electron energy-loss spectroscopy (EELS) allows catalytic products to be detected and quantified directly in the electron microscope. With aberration corrected TEM, the positions of atomic columns on nanoparticles surfaces can be observed and correlated with changes in conversion. New developments in monochromated EELS allow the electronic and vibrational structure of catalyst surfaces to be probed with focused electron beams. Using the so-called "aloof beam" approach to EELS, radiation damage is minimized potentially allowing electronic surface and defect states to be observed and correlated with catalytic properties. Examples will be shown which illustrate the information that can be obtained with modern electron imaging and spectroscopy. In situ observations of the structural and chemical changes during activation of reforming catalysts consisting of Ni or NiRu nanoparticles on non-reducible (SiO2) and reducible (CeO2 or doped CeO2) supports will be described. The evolution of the metal and bimetallic structures can be correlated with conversion and selectivity to provide an understanding of nanoscale structure-reactivity relations for partial oxidation and steam reforming. Recent advances in the development of operando methods will be illustrated for CO oxidation on Ru where correlating reactio

  66. Chemistry Department Colloquium


    Presented by Antoni Llobet, Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, E-43007 Tarragona, Spain., Spain

    Friday, August 19, 2016, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dmitry Polyansky

    Abstract The replacement of fossil fuels by a clean and renewable energy source is one of the most urgent and challenging issues our society is facing today, which is why intense research is devoted to this topic today. Nature has been using sunlight as the primary energy input to oxidize water and generate carbohydrates (a solar fuel) for over a billion years. Inspired, but not constrained, by nature, artificial systems[1] can be designed to carry out redox catalysis induced by light for instance to oxidize water and reduce protons or other organic compounds to generate useful chemical fuels. In this context this contribution will present a variety of molecular water oxidation and proton reduction catalysts[2] based on first row and second row transition metal complexes. Their capacity to carry out these reactions induced by light will be analyzed and discussed.[3] References [1] Berardi, S.; Drouet, S.; Francàs, L.; Gimbert-Suriñach, C.; Guttentag, M.; Richmond, C.; Stoll, T.; Llobet, A. Chem. Soc. Rev., 2014, 43, 7501-7519. [2] (a) Neudeck, S.; Maji, S.; López, I.; Meyer, S.; Meyer, F.; Llobet, A. J. Am. Chem. Soc. 2014, 136, 24-27. (b) López, I.; Ertem, M. Z.; Maji, S.; Benet-Buchholz, J.; Keidel, A.; Kuhlmann, U.; Hildebrandt, P.; Cramer, C. J.; Batista, V. S.; Llobet, A. Angew. Chem. Int. Ed. 2014, 53, 205-210. (c) Garrido-Barros, P.; Funes-Ardoiz, I.; Drouet, S.; Benet-Buchholz, J.; Maseras, F.; Llobet, A. J. Am. Chem. Soc. 2015, 137, 6758-6761. (d) Matheu, R.; Ertem, M.Z.; Benet-Buchholz, J.; Coronado, E.; Batista, V. S.; Sala, X.; Llobet, A. J. Am. Chem. Soc. 2015, 137, 10786-10795. [3] (a) Farras, P.; Di Giovanni, C.; Clifford, J. N.; Garrido-Barros, P.; Palomares, E.; Llobet, A. Green Chem., 2016, 18, 255-260. b) Moonshiram, D.; Gimbert-Suriñach, C.; Guda, A.; Picon, A.; Lehmann, C. S.; Zhang, X.; Doumy, G.; March, A. M.; Benet-Buchholz, J.; Soldatov, A.; Llobet, A.; Southworth, S. H. J. Am. Chem. Soc. 2016, 138

  67. Chemistry Department Seminar

    "Application of X-ray Absorption Spectroscopy to Electrocatalysts"

    Presented by Nebojsa Marinkovic, Synchrotron Catalysis Consortium and Department of Chemical Engineering, Columbia University, NY

    Monday, July 25, 2016, 10 am
    Room 300, Chemistry Bldg. 555 - 3rd Floor

    Hosted by: Miomir Vukmirovic

    The synchrotron-based X-ray absorption spectroscopy (XAS) is a non-destructive technique that measures the changes in the x-ray absorption coefficient of a material as the function of energy. The X-rays are highly penetrating and allow studies of gases, solids or liquid at concentrations of as low as a few ppm. As an element-specific technique, XAS can resolve the oxidation state of the element, as well as its coordination environment and subtle changes within. Its unique power is found in application to metal clusters, particularly in nanomaterials. It can resolve the inner structure of a nanoparticle composed of two or more elements, i.e. solid solution, aggregate mixtures, or core-shell particles in which one metal is present mostly in the center of the particle (core), and the other forms a shell around it. The latter nanoparticle systems are of a special interest for electrocatalysts composed of expensive noble metals because minimizing the noble metal content is the goal of the present technology development. The lecture focuses on in-situ characterization of electrochemical systems composed of two or more metal atoms for fuel cell technology. Selected examples show the changes in the inner structure of the catalyst during the oxidation of fuels on anode systems, or oxygen reduction on cathodes, including size, shape and partial oxidation state, and correlate them to the catalyst's activity and stability.

  68. Chemistry Department Seminar

    "Artificial Photosynthesis on III-Nitride Nanowire Arrays"

    Presented by Zetian Mi, Department of Electrical and Computer Engineering, McGill University, Canada

    Tuesday, June 21, 2016, 11 am
    Room 300, 3rd Floor, Chemistry Bldg. 555

    Hosted by: Jim Muckerman

    Abstract: High efficiency artificial photosynthesis, that can convert solar energy directly into chemical fuels, has been extensively investigated. Critical to this development is the stable and efficient generation of H2 from water under direct sunlight irradiation. To date, however, success in finding abundant visible-light active photocatalyst has been very limited. Recently, metal-nitrides have attracted considerable attention for applications in artificial photosynthesis, due to their extraordinary stability and tunable energy bandgap across nearly the entire solar spectrum. Moreover, III-nitrides are the only known material whose energy bandgap can straddle the redox potential of water under deep visible and near-infrared light irradiation. In 2011, we have demonstrated, for the first time, spontaneous overall water splitting on GaN nanowire arrays. We have discovered that the quantum efficiency for overall water splitting and hydrogen generation on the emerging nanostructured photocatalysts can be dramatically enhanced by precisely tuning the surface Fermi-level. We have further developed InGaN/GaN nanowire photoanodes and photocathodes, which are monolithically integrated on Si solar cell wafer through a polarization-enhanced tunnel junction. The devices exhibit highly stable hydrogen generation under simulated sunlight illumination. Such high efficiency photocatalysts also offer an entirely new avenue for recycling anthropogenic carbon dioxide to renewable fuels and for reducing nitrogen to ammonia. Zetian Mi is an Associate Professor in the Department of Electrical and Computer Engineering at McGill University. He received the Ph.D. degree in Applied Physics from the University of Michigan, Ann Arbor in 2006. Prof. Mi's teaching and research interests are in the areas of III-nitride semiconductors, solid state lighting, nanophotonics, and solar fuels. He has published 7 book chapters and more than 150 refereed journal papers. He has received ma

  69. Center for Functional Nanomaterials Seminar

    "Molecular Cluster as Superatoms in Solid-State Chemistry"

    Presented by Xavier Roy, Columbia University

    Thursday, June 9, 2016, 1:30 pm
    CFN, Bldg 735, Conference Room A, 1st Floor

    Hosted by: Matthew Sfeir

    Traditional solid-state compounds are infinite crystalline arrays of densely packed atoms. The emergence of collective properties in structured clusters of atoms, which we term "superatoms", offers a new class of fundamental building blocks for assembling materials. The superatom concept has the potential to usher in a new era where materials are designed to have a specific function, rather than discovered by trial and error. To realize this concept, we are exploring the use of molecular clusters as superatomic building blocks, designing and synthesizing not only the molecular clusters but also the means by which they interact. In this presentation, I will show how the atomic control and the diversity afforded by our superatoms allows us to dictate the structure of the solids and control the interactions between the building blocks. I will discuss how collective properties emerge from these interactions by providing examples of magnetic phase transition, electrical transport and thermal energy transport.

  70. Chemistry Department Seminar

    "Singlet O2 Oxidation of Guanine Nucleobase, Nucleoside and Guanine-Cytosine Base Pair: Ion-Beam Scattering Experiment Combined with Molecular Potential, Kinetic and Dynamics Simulations"

    Presented by Jianbo Liu, Dept. of Chemistry & Biochemistry, Queens College of the City University of NY

    Monday, June 6, 2016, 11 am
    Room 300, 3rd floor, Chemistry Building 555

    Hosted by: Trevor Sears

    Research focuses on using various instrumental analysis approaches (e.g., mass spectrometry, spectroscopy, and ion-molecule reactions) to probe biologically relevant processes in a spectrum of systems ranging from isolated biomolecules, through micelles and aerosols containing biomolecules, to biomolecule solution.

  71. Chemistry Department Colloquium


    Presented by Francisco Zaera, University of California, Riverside

    Monday, May 9, 2016, 10 am
    Hamilton Seminar Room, Bldg. 555


  72. Chemistry Department Colloquium

    "The Route to Better Catalysts; From Surface Science to Nanotechnology"

    Presented by Prof. Francisco Zaera, Dept. of Chemistry, University of California, Riverside

    Monday, May 9, 2016, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Sanjaya Senanayake

    One of the major challenges in heterogeneous catalysis is the preparation of highly selective and robust catalysts. The goal is to be able to synthesize solids with stable surfaces containing a large number of specific surface sites designed for the promotion of a particular reaction. New synergies between surface-science studies and novel nanosynthesis methodology promise to afford new ways to design such highly selective catalysts in a controlled way. Here we will provide a progress report on several projects ongoing in our laboratory based on this approach. First, we will offer a general discussion on the unresolved issues associated with olefin- conversion reactions promoted by metal surfaces. In a specific project, platinum-based catalysts were designed for the selective trans-to-cis conversion of olefins based on early surface-science work with model single-crystal surfaces and quantum mechanical calculations that indicated a particular preference for (111) facets in promoting the formation of the cis isomers. A metal- nanoparticle encapsulation procedure was also developed to increase catalyst stability and to prevent sintering. In a second example, new metal@TiO2 yolk-shell nanomaterials were conceived for both regular and photo-induced catalytic applications. These catalysts can promote CO oxidation at cryogenic temperatures, and suggest that in photocatalysis the role of the metal may not be to scavenge the excited electrons produced in the semiconductor upon absorption of light, as commonly believed, but rather to promote the recombination of the adsorbed atomic hydrogen initially produced by reduction of H+ on the surface of that semiconductor. Additional examples will be briefly introduced, including the use of "click" chemistry to tether molecular functionality on porous solid materials and the use of self-assembly and sol-gel chemistry to prepare catalysts with well-defined structural characteristics.

  73. Center for Functional Nanomaterials Seminar

    "Superoxide Solvation-Mediated Electrochemistry in Metal-Oxygen Batteries"

    Presented by Naga Phani B. Aetukuri, IBM Research-Almaden, San Jose, CA.

    Thursday, April 28, 2016, 11 am
    Building 735, Conf. Rm. A.

    Hosted by: Gregory Doerk

    Center for Functional Nanomaterials Seminar Batteries with high specific energy and energy density higher than that of state-of-the-art Li-ion batteries are considered critical for mass adoption of electric automobiles. Metal-oxygen batteries, Li- and Na-O2 batteries in particular, offer the highest theoretical specific energy among all known battery types. Li2O2 and NaO2, the discharge products in Li- and Na-O2 batteries respectively, are both electronic insulators. Therefore, electrochemical deposition of Li2O2 and NaO2 might lead to battery electrode passivation and to low actual specific energy. I will present experimental results backed by theoretical calculations that suggest the capacity limitations in these batteries can be overcome by enabling solution-mediated electrochemical deposition of Li2O2 and NaO2. This mechanism leads to a higher specific energy than that limited by electrode passivation. We have identified design rules for selecting electrolyte solvents that favor this alternate pathway and enable high specific energy metal-air batteries. I will also discuss our work on dendrite-resistant composite Li-ion conducting membranes which find applications in Li-ion and other lithium battery chemistries that would benefit from using a lithium anode.

  74. Chemistry Department Colloquium

    "Structure of Room-Temperature Ionic-Liquids as it Relates to Anomalous Transport"

    Presented by Claudio J. Margulis, University of Iowa

    Monday, April 25, 2016, 10 am
    Hamilton Seminar Room, Bldg. 555

    Ionic Liquids are defined by phenomena on different length scales. During this talk I will describe our most recent efforts to correlate their heterogeneous nanoscale structure as derived from X-ray scattering experiments with anomalous solute dynamics. Our work has contributed to the development of guidelines to interpret scattering results, however the connection, if any, between structure and dynamics is still unclear. Inroads to this extent will be discussed in the context of translational and rotational diffusion of smaller solutes.

  75. Center for Functional Nanomaterials Seminar

    "Sub-50 fs Photophysics and Photochemistry of Transition Metal Complexes and Polyhalomethanes"

    Presented by Sergey Mikhailovich Matveev, Bowling Green State University

    Monday, April 11, 2016, 1:30 pm
    CFN, Bldg. 735, 1st floor conf. rm. A

    Hosted by: Mircea Cotlet

    Lowest energy electronic excited states (LEES) in transition metal complexes are the states most relevant for practical photophysical and photochemical processes. We investigated relaxation dynamic of two systems – copper chloride dianion with strong Jahn-Teller effect and hexabromoiridate dianion with spin-spin coupling, utilizing 2000 nm near-IR femtosecond (100 fs) pump-probe spectroscopy. In both systems, the Franc- Condon excited states of the transition metal complexes undergo internal conversion to the ground electronic states, but with significantly different lifetimes (55 fs and 360 ps, respectively), despite the fact that the metal-centered states are separated by the same energy gap (~5000 wavenumbers) from the respective ground state. This difference is explained by presence of a conical intersection between the first excited electronic and the ground states in the Cu(II) system due to strong Jahn-Teller linear distortion whereas the involved potential energy surfaces for the Ir(IV) complex are nested directly one above another. Another project under consideration is the ultrafast mechanisms of polyhalomethanes on the example of diiodomethane. This molecule has a tractable number of degrees of freedom, and, therefore, has served in literature as a model system for bond dissociation processes in both gas and condensed phases. In this work we implemented the state-of-the-art ultrafast (~35 fs) transient absorption experiment (supported by the most accurate multireference quantum chemical methods) to understand the UV photodissociation mechanism of methylene iodide molecules. We discovered previously unsuspected photochemical pathway in the UV photochemistry of methylene iodide, in which electronically excited molecules, rather than simply dissociate, undergo direct ~50-fs isomerization through a conical intersection into isomeric species. Host: Mircea Cotlet

  76. Chemistry Department Colloquium

    "Old Problems Meet New Techniques: Applications of Frequency Comb-Referenced Spectroscopy"

    Presented by Dr. Trevor Sears, Brookhaven National Laboratory/Stony Brook University

    Monday, March 28, 2016, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Greg Hall

    I will describe some recent precision measurements of colliisonally-broadened line shapes in acetylene near 1.5 microns, then accurate rest frequency measurements for some hot band lines in the same region by sub-Doppler spectroscopy. Finally, we have recently been looking at the ammonia spectrum in the same wavelength region using the same techniques and find the observed partially resolved hyperfine splittings are diagnostic for individual rotational quantum number changes, so that the sub-Doppler lines can confirm or deny previous rotational assignments based on combination differences measured from Doppler-limited spectra. The measured hyperfine splittings should also give a signpost for potential ortho-para mixing that will occur in certain excited vibrational levels in NH3, and one observed transition showing anomalous hyperfine structure may indeed terminate in such a level. The presence of these mixed states has implications for the rates of ortho-para interconversion in the interstellar medium.

  77. Chemistry Department Colloquium

    "Water Oxidation for Solar Fuel Production"

    Presented by Prof. Gary Brudvig, Yale University

    Monday, February 22, 2016, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dmitry Polyanskiy

  78. Center for Functional Nanomaterials Seminar

    "The complexity of simple chemistry;"

    Presented by Matthijs A. van Spronsen

    Tuesday, November 3, 2015, 11 am
    CFN, Bldg. 735, conf. rm. A

    Hosted by: Anibal Boscoboinik

    Center for Functional Nanomaterials Seminar The complexity of simple chemistry; Development of in Operando SPM and the in situ oxidation of Pt(111) Matthijs A. van Spronsen Tuesday, November 3, 2015 11:00 am Bldg. 735 â€" Conf. Room A Matthijs A. van Spronsen¹, Sander B. Roobol¹, Joost W.M. Frenken¹, and Irene M.N. Groot¹⁻² ¹Huygens-Kamerlingh Onnes Laboratory, Leiden University, Leiden, The Netherlands ²Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands One interesting property of nanomaterials is their enhanced chemical reactivity. This property is frequently employed in the chemical industry. In industrial reactions, metallic nanoparticles can serve as catalysts to enhance the reaction rate or improve selectivity. The catalyst's activity is influenced by the nanoscale arrangement of surface atoms. Understanding catalysis, therefore, requires precise knowledge of the surface structure of nanoparticles. The difficulty, however, is that these structures often change under reaction conditions. To investigate surfaces under reaction conditions, we have developed a small reactor flow cell that is integrated with a scanning probe microscope. This microscope can serve both as Scanning Tunneling Microscope (STM) and Atomic Force Microscope (AFM) and operate in conditions of up to 6 bar and 600 K. As AFM, also electrically insulating samples can be studied, e.g., oxide-supported nanoparticles. This talk will partially focus on the development of the ReactorAFM. The AFM uses a miniature quartz tuning fork as force sensor. The force is measured between the sample and a micro-sized tip, which is grown by electron-beam-induced deposition of Pt. The design of the instrument and the challenges of NC-AFM at high pressure and high temperature conditio

  79. Chemistry Department Seminar

    "Acetylene spectroscopy, dynamics, and quantum control"

    Presented by David S. Perry, University of Akron

    Monday, October 19, 2015, 3 pm
    Room 300, Chemistry Bldg. 555 - 3rd Floor

    Hosted by: Trevor Sears

    The vibration-rotation dynamics of 1Σg+ acetylene are computed from a spectroscopic Hamiltonian with 468 parameters fit to 19,582 vibration-rotation transitions up to 13,000 cm-1 of vibrational energy. In this energy range, both the bending and the CH stretching vibrations can reach large amplitudes, but the maximum energy remains below the threshold for isomerization to vinylidene. In contrast to the behavior at energies below 5,000 cm-1 [1], excitation of single bright states leads, in almost all cases, to computed intramolecular vibrational redistribution (IVR) that is irreversible on the timescales investigated [2]. Hierarchies of IVR processes on timescales ranging from 20 fs to 20 ps result when different bright states are excited. Different parts of the vibrational quantum number space are explored as a result of the four different classes of coupling terms: (a) vibrational l-type resonance, (b) anharmonic resonances, including DD4455 and DD1133, (c) rotational l-type resonance, and (d) Coriolis couplings. The initial IVR rates are very different depending on whether the bright states are bending states or stretching states, normal modes or local modes, edge states or interior states. However, the rates of the rotationally mediated couplings do not depend substantially on these distinctions. Notably, the local bender bright state does not show special stability against the rotationally mediated couplings. The local bender involves motion along a coordinate that, at higher energy, becomes the reaction coordinate connecting acetylene to vinylidene. The volume of phase space explored increases steadily over three decades of time for most bending bright states, showing a more-or-less linear increase on a logarithmic time scale. Different patterns are seen for cis-bend and CH-stretch bright states. The total volume of phase space explored depends strongly on

  80. Center for Functional Nanomaterials Seminar

    "Electrochemistry on Nano- and Atomic Levels: Scanning Probe Microscopy Meets Deep Data"

    Presented by Sergei V. Kalinin, Center for Nanophase Materials Sciences, ORNL

    Thursday, October 15, 2015, 11 am
    Bldg 735, Conference Room C, 2nd Floor

    Hosted by: Eric Stach

    Structural and electronic properties of oxide surfaces control their physical functionalities and electrocatalytic activity, and are currently of interest for energy generation and storage applications. In this presentation, I will discuss several examples of high-resolution studies of the electronic and electrochemical properties of oxide surfaces enabled by multidimensional scanning probe microscopies. On the mesoscopic scale, combination of strain- and current sensitive scanning probe microscopies allows to build nanometer-scale maps of local reversible and irreversible electrochemical activities. The use of multivariate statistical methods allows separating the complex multidimensional data sets into statistically significant components which in certain cases can be mapped onto individual physical mechanisms. I will further discuss the use of in-situ Pulsed Laser Deposition growth combined with atomic resolution Scanning Tunneling Microscopy and Spectroscopy to explore surface structures and electrochemical reactivity of oxides on the atomic scale. For SrRuO3, we directly observe multiple surface reconstructions and link these to the metal-insulator transitions as ascertained by UPS methods. On LaxCa1-xMnO3, we demonstrate strong termination dependence of electronic properties and presence of disordered oxygen ad-atoms. The growth dynamics and surface terminations of these films are discussed, along with single-atom electrochemistry experiments performed by STM. Finally, I explore the opportunities for atomically-resolved imaging and property data mining of functional oxides extending beyond classical order parameter descriptions, and giving rise to the deep data analysis in materials research. This research is supported by the by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division, and was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laborator

  81. Poster Session

    "Stony Brook University Students Poster Session - Chemistry Dept."

    Friday, October 2, 2015, 2 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Trevor Sears

    Poster Session - Stony Brook University Students from Chemistry Department will be presenting their posters in the lobby of the Chemistry Building 555.

  82. Chemistry Department Seminar

    "Dynamic Structural Disorder in Supported Nanocatalysts Under Operando Conditions as probed by X-ray Spectra*"

    Presented by John J. Rehr, University of Washington

    Monday, September 21, 2015, 2 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Anatoly Frenkel

    Supported nanoparticle catalysts are ubiquitous in heterogeneous catalytic processes, and there is broad interest in their physical and chemical properties. However, global probes such as XAS and XPS generally reveal their ensemble characteristics, obscuring details of their fluctuating internal structure. We have previously shown [1] that a combination of theoretical and experimental techniques is needed to understand the intra-particle heterogeneity of these systems [2], and their changes under operando conditions [3]. Here we briefly review the theoretical calculations of both the dynamic structure and the spectra. Ab initio DFT/MD simulations revealed that the nanoscale structure and charge distribution are inhomogeneous and dynamically fluctuating over several time-scales, ranging from fast (200-400 fs) bond vibrations to slow fluxional bond breaking (>10 ps). The anomalous behavior of the disorder is not static, but rather is driven by stochastic motion over 1-4 ps time-scales. The resulting large scale fluctuations are termed "dynamic structural disorder" (DSD) [2]. Moreover, the nanoparticles tend to exhibit a semi-melted cluster surface, which for alloy clusters can be atomically-segregated. Recent studies of Pt and PtSn nanoclusters on various supports show a variety of spectral and structural trends as a function of temperature. DFT/MD simulations show that adsorption drives local electronic structure changes that are responsible for the energy shifts vs temperature of the absorption edge. In order to examine relaxation dynamics in the much longer, ns-scale time regimes we have recently developed modified Sutton-Chen (SC) potentials supplemented with a Lennard-Jones model potential to account for the interaction with the support. The modified SC parameters are chosen to capture the nanoparticles DFT dynamics. These simulations reveal regimes controlled by internal particle melting and activation of surface mobility. *Supp

  83. Chemistry Department Seminar

    ""Tracking atoms and charges in metal catalysts under reaction conditions"

    Presented by Anatoly I. Frenkel, Physics Dept, Yeshiva University, NY

    Tuesday, September 8, 2015, 10 am
    Room 300, 3rd Floor, Chemistry Bldg. 555

    Hosted by: Alex Harris

    In the last decade, complexity of catalytic nanoparticles attracted much attention as a major factor in catalytic processes. Atomic and electronic structure and dynamics of particles, as well as their interactions with support and adsorbates, are important descriptors of their catalytic activity. The main challenge is how to investigate these factors in a working catalyst, at high temperature and pressure, and how to do so without breaking the correlations between components of this complex system. I will give a brief overview of new methods developed recently to enable such combined studies under realistic reaction conditions. Our approach is to single out electronic charge of metal atoms in a cluster as an "observable" quantity and develop methods to "observe" it experimentally under realistic reaction conditions, and model theoretically. In this framework, complex interactions between metal and adsorbates, metal and support, and support and adsorbates can be all accounted for in terms of their effects on the cluster charge. I will review recent results utilizing this approach for a prototypical catalyst, 1nm Pt nanoparticles supported on silica. Using high energy resolution methods of X-ray absorption and emission spectroscopies (HERFD and RIXS), as well as in situ IR spectroscopy (DRIFTS) and electron microscopy, aided with first-principles (DFT) modeling, we deduced that the structure of atoms and charges in the catalyst is strongly heterogeneous and that it changes dynamically with the change in temperature and pressure of adsorbates (H2 or CO).

  84. Chemistry Department Seminar

    "Transition Metal Oxide Electrodes for Stationary Sodium-Ion Batteries"

    Presented by Prof. Yong-Sheng Hu, Institute of Physics, Chinese Academy of Sciences, China

    Monday, August 17, 2015, 2 pm
    Room 300, 3rd Floor, Chemistry Bldg. 555

    With the tremendous development of renewable energies such as solar and wind powers, the smooth integration of their energies into the grid, thus improving the grid reliability and utilization, critically needs large-scale energy storage systems with long-life, high efficiency, high safety and low cost. Among the various energy storage technologies, electrochemical approach represents one of the most promising means to store the electricity in large-scale because of the flexibility, high energy conversion efficiency and simple maintenance. Due to the highest energy density among practical rechargeable batteries, lithium-ion batteries have been widely used in the portable electronic devices and would undoubtedly be the best choice for the electric vehicles. However, the rarity and non-uniform distribution of lithium in the Earth's crust may limit their large-scale application in renewable energy. In this regard, room-temperature sodium-ion batteries with lower energy density compared with lithium-ion batteries have been reconsidered particularly for such large-scale applications, where cycle life and cost are more essential factors than energy density owing to the abundant sodium resources (2.75%) and potentially low cost as well as similar "rocking-chair" sodium storage mechanism as lithium. In this presentation, I will present several layer- and tunnel-type transition metal oxide electrodes for room-temperature stationary sodium-ion batteries. In the case of layer-type metal oxides, based on our new significant finding of highly electrochemical reversibility of Cu2+/Cu3+ redox couple in Na-containing layered oxides, I will emphasize our recent work on a series of air-stable and Co/Ni-free layered metal oxide cathodes which exhibit superior Na storage performance. The prototype sodium-ion batteries constructed from our developed cathode and anode materials will also be demonstrated. Furthermore, we recently propose a new strategy t

  85. Chemistry Department Colloquium

    "Hydrogen Storage in Formic Acid/Formate Solutions - Kinetics and Mechanism"

    Presented by Prof. Laurenczy Gabor, Ecole Polytechnique Federale de Lausanne, Switzerland

    Friday, August 14, 2015, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Etsuko Fujita

  86. Colloquium

    "Atmospheric Chemistry Colloquium for Emerging Senior Scientists (ACCESS XII)"

    Saturday, August 1, 2015, 8 am
    Berkner Hall, Room B

    Hosted by: Ernie Lewis

  87. Colloquium

    "Atmospheric Chemistry Colloquium for Emerging Senior Scientists (ACCESS XII)"

    Friday, July 31, 2015, 8 am
    Berkner Hall, Room B

    Hosted by: Ernie Lewis

  88. Colloquium

    "Atmospheric Chemistry Colloquium for Emerging Senior Scientists (ACCESS XII)"

    Thursday, July 30, 2015, 8 am
    Berkner Hall, Room B

    Hosted by: Ernie Lewis

  89. Chemistry Department Seminar

    "Synthesis and Characterizations of Novel Anode Materials for Lithium Ion Batteries"

    Presented by Dr. Tianchan Jiang

    Monday, June 22, 2015, 4 pm
    Room 300, Chemistry Bldg. 555

    Hosted by: Dr. Xiao-Qing Yang


  90. Chemistry Department Seminar

    "Interfacial Engineering for Directed Self-Assembly of Block Copolymer Thin Films"

    Presented by Hyo Seon Suh, Institute for Molecular Engineering, University of Chicago

    Tuesday, June 2, 2015, 10 am
    Bldg 735, CFN, Conference Room A, 1st Floor

    Hosted by: Chuck Black

    The attempt to use thin films of block copolymers (BCPs) as the templates for nanofabrication, known as BCP lithography, has recently become a subject of special interest since the BCP can spontaneously form highly uniform nanostructures smaller than the resolution limit of current lithographic tools. For technological applications, the nanostructures of BCP thin films often must be controlled by design. In this talk, the strategies to control nanostructures of BCP films with the designed boundary conditions will be discussed. The final morphology of BCP films are not only affected by the interfacial interaction at the bottom substrate but also affected by the free surface of BCP films. Interfacial engineering for both interfaces of BCP films enables us to achieve specific, sought-after domain orientations. This interfacial engineering becomes especially critical for further reducing the feature size of BCP down to sub-10 nm, which requires the use of BCPs that can form smaller feature than the scaling limit of PS-b-PMMA. Experimental and theoretical delineation of the design rules for directed self-assembly (DSA) of high resolution BCP films will be discussed. Finally, the interfacial engineering that enables the easy release of directed assembled BCP films from the guiding templates will be also introduced. By using this strategy, pre-DSA BCP films on a single template can be transferred to the wide range of template-free substrates. This BCP printing method will widely broaden the application area of BCP lithography.

  91. BECS Department Seminar

    "Four decades of seed oil biochemistry. What have we learnt and what is left to discover?"

    Presented by Sten Stymne, Department of Plant Breeding, Swedish University of Agricultural Sciences, Sweden

    Thursday, October 30, 2014, 11 am
    John Dunn Seminar Room, Bldg. 463

    Hosted by: John Shanklin

  92. Chemistry Department Symposium

    "Honoring Carol Creutz"

    Wednesday, October 29, 2014, 9 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Alex Harris

    Symposium to be held at Brookhaven National Laboratory to honor Late Senior Chemist Emeritus, Carol Creutz On the morning of Wednesday, October 29 a half-day symposium will be held in the Hamilton Seminar Room, Chemistry Building, 555 to honor the science contributions of Carol Creutz, who had a 41 year career in the Brookhaven Chemistry Department. Creutz was a leader in research on photocatalysis to convert solar energy to fuels, working in the DOE Solar Photochemistry program for most of her Brookhaven career. The symposium will honor Creutz's scientific contributions with presentations by several of Creutz's former collaborators and colleagues. Creutz was a leader in the study of molecular transition metal complexes, which have a rich and varied chemistry including the ability to catalyze important chemical reactions. Many such complexes also absorb visible light strongly, and some can drive chemical reactions to store the light energy as chemical energy. Such processes are similar to the photosynthesis of green plants, which uses sunlight to convert water and carbon dioxide into high energy sugars. Creutz was active in the worldwide effort to create an equivalent solar-to-fuels process for human needs. She particularly focused on both light-driven and chemical processes that caused the loss or gain of electronic charge in transition metal complexes, and which could use the resulting changes in oxidation state to reduce or oxidize other molecules. These 'reduction-oxidation' processes are central to many modern solar-to-fuels schemes. The symposium speakers will discuss research directions pioneered in Creutz's work and how they have been foundations for modern research in inorganic chemistry and solar-to-fuels conversion. Carol Creutz came to BNL as a Research Associate in 1972, proceeded through the ranks to tenured chemist (1978) and Senior Chemist (1989). She was also Chair of

  93. Chemistry Department Seminar

    "Precise Design of Donor-Acceptor Interface based on Microphase Segregated Nanostructure"

    Presented by Sadayuki Asaoka, Kyoto Institute of Technology, Kyoto, Japan

    Friday, July 27, 2012, 1:30 pm
    Room 300, Chemistry Bldg. 555

    Hosted by: Dr. John Miller

  94. Chemistry Department Colloquium

    "“NOx Catalysis from the Bottom Up”"

    Presented by Dr. William F. Schneider, Dept. of Chemical and Biomolecular Engineering, University of Notre Dame

    Thursday, April 26, 2012, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Ping Liu

    In order to meet the increasing demands of energy sustainability and environmental protection, catalysis science and application in the 21st century has to be driven by basic insights into how materials function and how they can be improved. The advent of first-principles simulations based on density functional theory (DFT), which are able to reliably simulate chemical structures and reactions at the molecular scale, has been instrumental in the recent renaissance in heterogeneous catalysis research. In this talk, I will illustrate the capabilities and challenges of applying these simulation tools in the context of the catalytic chemistry of nitrogen oxides (NOx). NOx is an unwanted by-product of combustion and is particularly difficult to remove from lean combustion sources, such as diesel engines. NOx also has rather complex chemistry that presents special challenges to simulation. I will describe some of our successes in understanding NOx chemistry from first-principles, with a first emphasis on recent work to capture the essential features of the beguiling simple catalytic oxidation of NO to NO2 over metals and metal oxides, to reconcile these models with experimental results, and to use these insights to guide the selection of new and improved catalysts. I will then discuss recent work to extend the same concepts to the selective catalytic reduction of NOx over narrow-pore metal-exchanged zeolites, a new class of effective and stable catalysts. Figure: Dynamic simulation of an O-covered Pt surface catalyzing NO oxidation to NO2. From Wu et al. J. Catal. 2012, 286, 88-94.

  95. Chemistry Department Colloquium

    "High-energy resolution x-ray emission spectroscopy for catalysis and materials chemistry"

    Presented by Olga Safonova, Swiss Light Source & Energy Dept. at Paul Scherrer Institute, Switzerland

    Friday, April 13, 2012, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dario Stacchiola

    New possibilities of high-energy-resolution x-ray emission spectroscopy for structural studies catalysts and applied materials will be discussed and compared to traditional XAS. Based on selected examples it will be shown how improvement of energy resolution of XANES, chemical sensitivity of emission lines and resonance inelastic X-ray scattering (RIXS) can help answering difficult scientific questions. Interests are focused on the understanding of structure-function relations in heterogeneous catalysis and material science. The highlights include (i) probing of geometry of CO adsorption sites and reactivity on platinum and gold nanoparticles using HERFD XAS at the Pt and Au L3 edges, (ii) application of valence-to-core XES to study the local structure of Cr, Fe, Co and Ni in amorphous metal coatings, and to prove the formation of V-N bonds in V/Al2O3 catalyst for selective propane ammoxidation , (iii) developing of an in situ reactor for the study of the mechanism of deactivation of cobalt and iron Fischer-Tropsch catalysts under conditions mimicking the industrial applications at high pressures using in situ XRD combined with XAS at Co K- Fe K- and Pt K-edges.

  96. Chemistry Department Seminar

    "Comparing the Primary Electron Transfer Process in Photosynthetic Reaction"

    Presented by Garry Rumbles, National Renewable Energy Laboratory (NREL), Golden, Colorado,

    Friday, April 6, 2012, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: John Miller

    This presentation will focus on some of the fundamental science associated with the rapidly emerging field of organic photovoltaics (OPV). It will include a discussion of how the OPV field is evolving, examine some of the fundamental scientific issues that underpin the subject, and will discuss how spectroscopy can help to understand these issues. The goal is to enable both a better understanding of how these systems function and consequently help to advance solar energy conversion efficiencies of future OPV devices. So-called organic photovoltaic devices have seen certified power conversion efficiencies increase from 2.5% in 2001 to ~9% in 2011. Close inspection of the strategies employed to realize this impressive improvement in performance reveal a common approach of synthesizing new donor polymers, fullerene acceptors and, in some cases, new device architectures. It is questionable as to whether this approach will result in a similar four-fold level of improvement over the next ten years. And it is the answer to this question that motivates the work that will be described. At the heart of all OPV devices is the donor-acceptor interface, where photogenerated excitons are dissociated into separated charge carriers. Using flash photolysis, timeresolved microwave conductivity (fp-TRMC) as a tool for detecting mobile carriers, a number of recently-studied systems will be described. This particular presentation will focus on systems that contain new conjugated polymers and novel derivatives of fullerenes. These studies will serve to highlight a fundamental issue that we have yet to fully understand: how are these carriers created with such efficiency and yield, and in a system that does not immediately suggest that this is possible? The talk will include a speculative discussion about how we might better understand this process by looking at the function of Nature’s photosynthetic reaction centers.

  97. Chemistry Department Colloquium

    "New catalysts and nanostructures for the production of solar fuels"

    Presented by Craig L. Hill, Emory University, Department of Chemistry

    Wednesday, April 4, 2012, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dmitry Polyanskiy

    To realize viable (fast, stable and cost effective) devices or nanostructures for the production of solar fuels, the research community must improve the core operating units and their integrated (device) formulations. These operating units involve (a) light absorption with charge separation,(b) multi-electron-reduction catalysts (CO2 and H2O as primary substrates) and (c) water oxidation catalysts (WOCs). Our multi-group team at Emory University is tackling these challenges by new approaches but building on many informative complementary studies in the literature. Most of the systems we are developing contain or are based on soluble, tunable transition metal oxide cluster anions (polyoxometalates or “POMs”). We have developed POM WOCs that are carbon-free (thus resistant to oxidative degradation), stable to hydrolysis (the pH range of stability depends on the POM and is controllable), and stable to heat. The first three WOCs of this class, two based on POM-stabilized Ru4O4 units1-3 structurally reminiscent of the OEC (Mn4CaO4) unit, and one based on a Co4O4 unit,4 are very fast, but we will present the systematic development of a new POM WOC that is more hydrolytically stable in basic aqueous medium (the desirable one for practical water oxidation) and turns over far faster than any synthetic catalyst reported to date (up to 1000/s, depending on conditions). We will also describe a multi-manganese-containing POM catalyst for multielectron reductions (H2O to H2 and CO2 to CO). It shares the many benefits of our POM WOCs, including its compatibility with water, but on the negative side, it’s slow without help (potential from biased anode or CT excited states of photosensitizer systems). We will conclude with new types of carbon-free photosensitizers5 and brief note of dyads and triads contained these new types of catalysts.

  98. Center for Functional Nanomaterials Seminar

    "Surface Chemistry over Model Catalysts: from the Atomic-Scale under UHV"

    Presented by Ashleigh Baber

    Thursday, March 29, 2012, 10 am
    CFN, Building 735, conf. rm. B

    Hosted by: Peter Sutter

    Using model catalysts, we have studied the fundamentals of surface and adsorbate structure and identity. Bimetallic alloys play a central role in a wide variety of industrial catalytic reactions. Scanning tunneling microscopy (STM) was used to investigate the atomic-scale electronic and geometric structure of Pd/Au(111) and Pd/Cu(111) bimetallic model catalysts, as well as their interaction with hydrogen, a vital component in alcohol synthesis and water-gas shift reactions. We demonstrate that individual, isolated Pd atoms in an inert Cu matrix are active for the dissociation of hydrogen and subsequent spillover onto Cu sites, but no H was found under the same H2 flux on a Pd/Au samples with identical atomic composition and geometry. In the case of Au, larger ensembles of Pd were required to activate H2 dissociation.1 These results demonstrate the powerful effect of the substrate on the catalytic activation of Pd atoms supported within or on its surface.2 Hydrogen, along with carbon monoxide, is used in the catalytic production of methanol. Fundamentally, methanol represents the simplest alcohol for understanding hydrogen-bonded networks. STM was used to investigate the stability and structure of methanol3 and formic acid on model systems. Similarly, formic acid has great importance for its use as a liquid fuel in direct formic acid fuel cells, and formates are considered important intermediates in several key catalytic reactions including the water-gas shift, alcohol synthesis and decomposition, and the hydrogenation of oxygenates. To obtain a full picture of the morphological and chemical changes during model catalytic studies, X-ray photoelectron spectroscopy (XPS) experiments, from UHV to near-ambient pressure (NAP) conditions, are presented to provide insight into the correlation between adsorbate identity and model catalysts structure.

  99. Center for Functional Nanomaterials Seminar

    "Photocleavage Controlled DNA Switches and Nanochemistry for Noobs"

    Presented by Philip Lukeman, St. John's University

    Monday, February 13, 2012, 11 am
    Bldg 735 - Conf Rm B

    Hosted by: Oleg Gang

    DNA-based switches are currently operated by manual, solution-phase addition of ‘set-strands’. I will describe another operation method - sterically inaccessible ‘set-strands’, released from a surface into solution by spatially controlled photocleavage, that operates both stochiometric and catalytic set-strand controlled systems. This technique will enable microarrays of set-strands to operate many DNA-based switches in computational and diagnostic devices. DNA Nanotechnology research is currently conducted in labs across the globe, primarily by Graduate students and Postdoctoral researchers. This seminar will also outline how we design small-scale but real research projects to act as meaningful training of Undergraduate and High-School students.

  100. Chemistry Department Colloquium

    "Proton-Coupled Electron Transfer: From Marcus Theory to Electrocatalysis to Nanoparticles"

    Presented by John M. Mayer, University of Michigan, Seattle, WA, Dept. of Chemistry

    Thursday, February 9, 2012, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dmitry Polyansky

    A wide range of chemical processes can be termed proton-coupled electron transfer (PCET), from combustion to water oxidation to the redox dissolution of minerals. This presentation will begin with fundamental studies of single reaction steps that involve transfer of one proton and one electron. Some of these reactions ‘look like’ hydrogen atom transfers, such as oxyl radicals abstracting H• from vitamin C, while in other reactions the electron and proton are quite separated in the reactants or products, as in equation 1. Many of these reactions can typically be using a version Marcus Theory, to good accuracy. The Marcus approach shows the commonality of organic and transition metal H-atom transfer reactions, and the success of this approach raises fundamental issues. The second portion of the presentation will present initial results on projects extending these ideas to new water-oxidation and oxygen-reduction catalysts. For instance, the iron porphyrin complex at right is a good electrocatalyst for O2 reduction in acidic acetonitrile, with the pendant carboxylic acid ‘proton relays’ enhancing the selectivity for the 4e– reduction to water. The closing section of the presentation will use PCET concepts to provide new insights into the properties and reactivity of metal oxide nanoparticles, and by implication all metal-oxide/solution interfaces. In one example, reduced ZnO and TiO2 nanoparticles transfer e– and H+ (H•) to a phenoxyl radical:

  101. Chemistry Department Seminar

    "Gas Phase Inorganic Chemistry: Spectroscopy of Metal-Containing Molecules"

    Presented by Peter Bernath, Old Dominion University

    Thursday, January 26, 2012, 10 am
    Chemistry Room 300

    Hosted by: Trevor Sears

  102. Chemistry Department Seminar

    "Gas Phase Inorganic Chemistry: Spectroscopy of Metal-Containing Molecules"

    Presented by Dr. Peter Bernath, Old Dominion University, Norfolk, VA

    Thursday, January 26, 2012, 10 am
    Room 300 - Chemistry Bldg. 555

    Hosted by: Trevor Sears

    A variety of simple metal-containing molecules have been synthesized in the gas phase and studied by infrared emission or laser excitation spectroscopy. For example, the metal dihydrides BeH2 and HgH2 were made a high temperature furnace combined with an electrical discharge and detected via vibration-rotation emission spectroscopy. The monovalent metal-ligand species SrNH2, SrCH3, and CaBH4 were made in a laser-ablation molecular jet source and high resolution laser excitation spectra recorded. The analysis of calcium monoborohydride completes the isoelectronic CaF, CaOH, CaNH2, CaCH3 and CaBH4 family of molecules. These species are simple models for more complex inorganic compounds and some of them are found in energetic environments such as flames and stellar atmospheres.

  103. Chemistry Department Seminar

    ""Synthesis and Characterization of Conducting Doped Metal Oxide"

    Presented by Chinmayee Subban, Cornell University, Dept. of Chemistry

    Monday, December 19, 2011, 2 pm
    Room 300 - Chemistry Bldg. 555

    Hosted by: Peter Khalifah

    Under the pH and potential conditions of a PEMFC, sulfides, carbides and nitrides are all thermodynamically driven to oxidize or hydrolyze to oxides, at least at the surface. According to Poubaix diagrams, certain oxides with metals in their highest oxidation states appear to be stable under these conditions. However, since in each case the metal is in its highest oxidation state, these oxides are not conducting, but they can be partially reduced or doped with other metal cations, resulting in metallic or semiconducting behavior. With the motivation of replacing currently used carbon black catalyst supports in PEMFCs, the synthesis, characterization, chemical stability, and electrochemical testing of a family of such conducting doped metal oxide nanoparticles will be discussed.

  104. Chemistry Department Seminar

    "“Characterization and Surface Chemistry on Au-Based Bimetallic Clusters: Adsorbate-induced Diffusion and Reaction at Interfacial Sites”"

    Presented by Donna A. Chen, University of South Carolina, Dept. of Chemistry & Biochemistry

    Monday, December 12, 2011, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Ping Liu

    The nucleation, growth and surface composition of Au-based bimetallic clusters (Au-X where X=Ni, Pt, Co) on titania have been investigated as model systems for understanding how surface chemistry can be controlled by bimetallic composition and interactions between the clusters and the oxide support. Scanning tunneling microscopy studies demonstrate that bimetallic clusters are formed by seeding the mobile Au atoms at existing Ni, Pt and Co clusters due to the higher mobility of Au atoms compared to the second metal. The cluster surfaces are almost pure Au at Au compositions greater than 50%; however, adsorbates such as CO and methanol induce diffusion of Ni and Pt to the cluster surface. After heating to 800 K, the Ni and Pt in the bimetallic clusters become selectively encapsulated by titania while the Au remains at the cluster surface. The resulting clusters have an extended network of Au-titania sites, which are believed to be the active sites in oxidation reactions on titania-supported Au clusters. The nature of the Au-titania interfacial sites is probed by methanol reaction since the production of formaldehyde is believed to occur at the Au-titania interface.

  105. Chemistry Department Seminar

    "“High Resolution Optical spectroscopy of charge transfer doping and electrochemical processes in polymer semiconductor devices”"

    Presented by Riccardo Di Pietro, University of Cambridge, U.K.

    Monday, December 5, 2011, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Matthew Bird

    We have developed a high sensitivity optical spectroscopy technique that allows monitoring subtle changes of the optical absorption of an organic material at a sensitivity level of few parts in 10000 as a function of time. This technique allows in-situ spectroscopic investigation of some of the key electronic processes in fully functional device structures. We successfully applied the technique to study the mechanism of charge transfer doping of conjugated polymer films by MoO3. We were able to quantify doping efficiency and investigate the stability of the doped device in time, correlating the decrease in doping efficiency to the changes in the molybdenum trioxide energetic structure. We have also used the technique to investigate the mechanism for electron trapping in n-type organic FETs of poly{[N,N9-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene) (P(NDI2OD-T2)). The fundamental role of the atmosphere composition in the stressing mechanisms is determined by comparing device stability in vacuum and in air, and the results are analysed in view of possible electrochemical reactions involving charged polymer units and both O2 and H2O.

  106. Chemistry Department Seminar

    "Biomimetic Models of Radical Stress and Related Biomarkers"

    Presented by Dr. Chryssostomos Chatgilialoglu, ISOF, Consiglio Nazionale delle Ricerche, Bologna, Italy

    Tuesday, November 22, 2011, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: James Wishart

    The biological consequences of the free radical production are the central subject of a very lively scientific debate, focusing on the estimation of the type and extent of damage, as well as the efficiency of the protective and repair systems. When studying free radical based chemical mechanisms, it is very important to establish biomimetic models, which allow the experiments to be performed in a simplified environment, but suitably designed to be in strict connection with cellular conditions. The biomimetic modeling approach has been coupled with physical organic chemistry methodologies and the basic knowledge of free radical reactivity, thus allowing the molecular basis of important processes, as well as molecular libraries of products concerning unsaturated lipids, sulfur-containing proteins and nucleic acids, to be identified. In this context, radiation-induced transformations have been considered in depth together with the systematic study of all possible factors that drive reactivity in aqueous medium and the characterization of reaction or degradation products. This research leads to the discovery of new biomarkers and molecular libraries to be used for the evaluation of radiation effects. Ongoing projects in our group deal with lipidomics, genomics and proteomics of free radical stress and some examples will be described: (i) radical generation in the different positions of the sugar residue or purine base, and clarification of important reaction intermediates by pulse radiolysis;1 (ii) cis-trans isomerisation of unsaturated fatty acids with the formation of trans lipids in liposome systems;2 (iii) tandem damage of lipids and sulfur-containing proteins, with the event of post-translational modifications of amino acid sequences containing cysteine and methionine.3 Recent Selected References: 1) (a) Chatgilialoglu, C.; Ferreri, C.; Terzidis, M. A. Chem. Soc. Rev. 2011, 40, 1368. (b) Belmadoui, N.; Boussicault, F.; Guerra, M.; Ravanat, J. L.; Chatgili

  107. Chemistry Department Seminar

    "Approach to Artificial Photosynthesis by Two Electron Activation of Water by Visible Light"

    Presented by Prof. Haruo Inoue, Tokyo Metropolitan University, Tokyo, Japan

    Friday, November 18, 2011, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Etsuko Fujita and Yasuo Matsubara

    Artificial photosynthesis by visible light is one of the most desirable chemical systems to be realized. The possibility, however, still remains questionable, in spite of enormous efforts over the past several decades, since the most important problem of how to utilize the water molecule as an electron donor has not yet been fully solved. Oxidation of water, as an ideal electron donor, should be one of the central subjects of study. Among various approaches for the oxidation of water upon light irradiation, i.e., by 1) a one-electron process, 2) a two-electron one, 3) or a multi-electron one, we have recently focused our attention on the two-electron oxidation of water sensitized by metalloporphyrins. In this seminar, chemical approach to artificial photosynthesis through the two electron activation of water by one photon excitation will be introduced.

  108. Chemistry Department Seminar

    "Nanostructuring Electrochemical Interfaces: Synthesis of Fuel Cell Catalyst/Support Systems"

    Presented by Prof. Carlos R. Cabrera, Depart. of Chemistry, University of Puerto Rico at Rio Piedras, Puerto Rico

    Thursday, November 17, 2011, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Dario Stacchiola

    The nanostructuring of electrochemical interfaces is important for the development of the next generation of energy sources such as Fuel Cells. In this area, several techniques and catalyst/support synthetic methods have been developed. Recently, our group has been involved on a new method known as the rotating disk slurry electrochemical (RoDSE) technique for the bulk preparation of catalysts/support materials for regenerative fuel cells. Our interest has been placed on the preparation of Pt/Vulcan and Pt/carbon nano-onions. For the oxygen reduction reaction (ORR), tailored molecular precursors have been used to prepare methanol tolerant Pd-Co nanocatalysts. Moreover, sputtering techniques have been used to prepare Pd nanoshells for the ORR. Wastewater treatment is another area of interest. Our group has been working on developing a bioreactor system for the oxidation of urea to ammonia to nitrogen in collaboration with NASA Ames Research Center. This has led to a possible bioreactor system to be adapted to NASA Life Support Systems. References 1. Eduardo Nicolau et al., Bioelectrochemical Degradation of Urea at Platinized Boron Doped Diamond Electrodes for Bioregenerative Systems”, Advance Space Research 2009, 44, 965-970. 2. Diana Santiago et al., Platinum Electrodeposition at High Surface Area Carbon Vulcan-XC72R Material Using a Rotating Disk-Slurry Electrode Technique, J. Electrochem. Soc., 2010, 157, F189-F195. 3. L. Cunci and C.R. Cabrera, Preparation and Electrochemistry of Boron-Doped Diamond Nanoparticles on Glassy Carbon Electrodes. Electrochemical and Solid State Letters 2011, 14, (3), K17-K19 4. L. La-Torre-Riveros et al., Synthesis of platinum and platinum-ruthenium-modified diamond nanoparticles. Journal of Nanoparticle Research 2011, 13, (7), 2997-3009.

  109. Chemistry Department Colloquium

    "Synthesis and Study of Nanostructured Electrocatalysts for Polymer Electrolyte Fuel Cells"

    Presented by Dr. Fabio Lima, University of Sao Paulo, Brazil

    Monday, October 17, 2011, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Miomir Vukmorovic

    This talk, will be presented by some recent developments of high active electrocatalysis for electrochemical reactions that take place in fuel cells. We will focus on the ethanol and borohydride electro-oxidation, and on the oxygen reduction for proton and anion exchange membrane fuel cells. It will be shown their electrocatalytic activities and reaction products distribution, which were followed by on line mass spectrometry.

  110. Chemistry Department Colloquium

    "Surface Modification to Control Electrocatalysis"

    Presented by Christopher Chidsey, Stanford University, Dept. of Chemistry

    Friday, October 7, 2011, 10 am
    Room 300 - Chemistry Bldg. 555

    Hosted by: Alex Harris

    The modification of electrode surfaces for immobilization of catalysts affects electrocatalytic efficiency, selectivity and stability. I will describe two recent examples: (i) the immobilization of metal complexes onto gold and carbon electrodes to promote the selective reduction of dioxygen to water and (ii) the protection of reactive electrodes by titanium dioxide during water oxidation. I will explore the benefits and limits of methods of surface modification with an eye to their application to other electrocatalytic systems. Electrocatalytic O2 Reduction by Covalently Immobilized Mononuclear Copper(I) Complexes: Evidence for a Binuclear Cu2O2 Intermediate," Charles C. L. McCrory, Anando Devadoss, Xavier Ottenwaelder, Randall D. Lowe, T. Daniel P. Stack, and Christopher E. D. Chidsey, J. Am. Chem. Soc. 133, 3696 (2011). Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation ," Yi Wei Chen, Jonathan D. Prange, Simon Duhnen, Yohan Park, Marika Gunji, Christopher E. D. Chidsey, Paul C. McIntyre, Nature Materials 10, 539 (2011).

  111. Chemistry Department Colloquium

    "Pervasiveness of Surface Metal Oxide Phases in Mixed Oxide Catalysts"

    Presented by Israel E. Wachs, Lehigh University

    Tuesday, September 27, 2011, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dario Stacchiola

    Mixed oxide catalytic materials possess two or more metal oxide components as found in bulk mixed metal oxides (stoichiometric oxides as well as solid solutions), polyoxo metalates (POMs), molecular sieves, zeolites, clays, hydrotalcites and supported metal oxides. Although it is now well established that two-dimensional surface metal oxide phases are present for supported metal oxides on traditional supports (e.g., Al2O3, TiO2, ZrO2, SiO2, etc.), it is not currently appreciated that such surface metal oxide species or phases are also present for other types of mixed oxides. For example, recent surface analyses have demonstrated that stoichiometric bulk mixed metal oxides also possess surface metal oxide phases that control their catalytic activity. For example, the catalytic active sites for methanol oxidation to formaldehyde over the bulk Fe2(MoO4)3 mixed oxide catalyst are surface MoOx species and not the bulk Fe2(MoO4)3 phase as previously thought in the catalysis literature. The nanometer sized clusters in POMs also possess surface species when a second metal oxide component is introduced (e.g., H3+xPW12-xMxO40). Deposition of metal oxides into molecular sieves, zeolites, clays and hydrotalcites also results in the metal oxide additive usually being present as surface metal oxide species that are the catalytic active sites for many redox and acid reactions. The formation of these surface metal oxide phases is driven by their low surface free energy and low Tammann temperature for many metal oxides of interest in catalysis (e.g., VOx, MoOx, CrOx, ReOx, WOx, etc.).

  112. Chemistry Department Colloquium

    "Model Compound Studies Towards The Catalytic Upgrade of Pyrolysis Oil In Vapor and Liquid Phases"

    Presented by Dr. Daniel E. Resasco, University of Oklahoma

    Monday, August 1, 2011, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dario Stacchiola

    An effective approach to stabilize pyrolysis oil is conducting the refining before condensation of the vapors occurs. Degradation by further reaction (oligomerization) occurs in the liquid phase and accelerates when the liquid is subsequently heated for fractionation or other processing. The proposed “catalytic cascade” incorporates a series of reactions that include: (a) formation of C-C bonds to extend the carbon backbone of short oxygenates to the desired gasoline/diesel range; (b) incorporation of short carbon fragments (C1-C3) into the aromatic ring of phenolic compounds; (c) deoxygenation of the resulting products to monofunctional compounds or hydrocarbons. The different catalysts used in this cascade include: basic catalysts (MgO, ZrO2, CsX zeolites), acidic catalysts (H-ZSM5, H-beta zeolites), mixed oxides (CeZrO2), supported metal catalysts (Cu, Ni, Ru, Pd supported on carbon nanotubes and monolith). These catalysts are used in the vapor phase or in liquid (biphasic) systems. The latter employs nanoparticle catalysts to stabilize water/oil emulsions and to conduct reactions at the liquid/liquid interface to benefit from the differences in solubility exhibited by the reactants (bio-oil) and products (bio-fuels) and achieve continuous reaction/separation. Daniel E. Resasco is a Professor of Chemical, Biological, and Materials Engineering at the University of Oklahoma. He holds the D. Bourne endowed Chair. He received his PhD from Yale University in 1983. He is author of more than 190 publications and 30 industrial patents in the areas of heterogeneous catalysis and carbon nanotubes. He has been a Presidential Professor, S. Wilson Professor, and in the last few years he was awarded the Oklahoma Chemist of the Year award by the American Chemical Society, the Yale Science and Engineering Association award, and the Regents Award for Superior Research. He is the founder of SouthWest Nanotechnologies, a commercial carbon nanotube produce

  113. Chemistry Department Seminar

    "Synthesis and Characterization of Bi-Metallic Nanoparticles Using the Micro-emulsion Method"

    Presented by David Buceta, University Santiago de Compostela, Spain

    Thursday, April 28, 2011, 11 am
    Room 300 - Chemistry Bldg. 555

    Hosted by: Radoslav Adzic

  114. Chemistry Department Colloquium

    "Imaging Brain Chemistry in Diseases of Addiction"

    Presented by Dr. Joanna Fowler, Brookhaven National Laboratory

    Wednesday, April 27, 2011, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Minfang Yeh

    Positron Emission Tomography (PET) measures the concentration and movement of a positron emitting radioisotope in a volume element of living tissue. When the positron emitting isotope such as carbon-11 (t1/2: 20.4 min) or fluorine-18 (t1/2: 110 min) is incorporated into a molecule which is targeted to a specific cellular element (receptor, transporter, enzyme) or when it is incorporated into a drug molecule, PET can provide information on biochemical transformations or the movement of drugs in the living human and animal body. This can provide unique new knowledge of biological pathways which are altered in disease and by drugs. The advancement of PET for biological applications requires innovation in radiotracer chemistry, particularly in the development of rapid synthetic methods for introducing the short-lived isotopes, carbon-11 and fluorine-18 into chemical compounds which are targeted to different cellular elements. In this presentation, we highlight some examples of development and applications selective radiotracers to measure drug action in the human brain. We will also highlight new radiotracer methods which will serve as scientific tools for advancing molecular imaging and knowledge of the human brain.

  115. National Synchrotron Light Source Lunch Time Seminar

    "Complexity behind Metal Organic Frameworks’ Chemistry"

    Presented by Jorge Gascon, Delft University of Technology, Catalysis Engineering – Chemical Engineering Dept, The Netherlands

    Friday, April 22, 2011, 12 pm
    Seminar Room, Bldg. 725

    Hosted by: Lin Yang

    During the last decade, Metal Organic Frameworks (MOFs) have attracted a great deal of attention in the field of nanostructured materials. The combination of organic and inorganic subunits in these crystalline porous materials has led to vast chemical versatility. In spite of initial skepticism owing to poor stability of the first MOF generation, impressive progress has been made during the last few years, yielding promising results in very different technological disciplines, such as, adsorption and heterogeneous catalysis. MOFs are indeed among the most sophisticated nano-structured solids: not only they possess high surface area and pore volume, but their chemical environment can be fine-tuned by selecting the appropriate building blocks, or by post-synthetic functionalization. In spite of the plethora of publications on the topic, very little is known about the factors that rule both the performance and the formation of this new class of materials. During this lecture, using two amino functionalized aluminum terephthalate based frameworks (NH2-MIL-53(Al)[1] and NH2-MIL-101(Al)[2]) as example, the reasons for the excellent CO2 capture ability and the step-by-step mechanism behind the competitive formation of these two MOF phases will be unraveled with the help of several in situ synchrotron based techniques. [1] a) A. Boutin, S. Couck, F.-X. Coudert, P. Serra-Crespo, J. Gascon, F. Kapteijn, A. H. Fuchs and J. F. M. Denayer, Microporous and Mesoporous Materials 2011, 140, 108-113; b) S. Couck, J. F. M. Denayer, G. V. Baron, T. Remy, J. Gascon and F. Kapteijn, Journal of the American Chemical Society 2009, 131, 6326-6327; c) S. Couck, T. Remy, G. V. Baron, J. Gascon, F. Kapteijn and J. F. M. Denayer, Physical Chemistry Chemical Physics 2010, 12, 9413-9418; d) E. Stavitski, E. A. Pidko, S. Couck, T. Remy, E. J. M. Hensen, B. M. Weckhuysen, J. Denayer, J. Gascon and F. Kapteijn, Langmuir 2011, 27, 3970-3976. [2] P. Serra-Crespo, E. V. Ramos-Fernandez, J. Gascon

  116. Chemistry Department Seminar

    "The Surface Reactions and Photoreactions of TiO2 Single Crystals and Catalysts: The case of hydrogen production."

    Presented by Dr. Hicham Idriss, Dept. of Chemistry, University of Aberdeen, UK SABIC T&I, Riyadh, Saudi Arabia

    Thursday, April 21, 2011, 1:30 pm
    Room 300 - Chemistry Bldg. 555

    Hosted by: Dario Stacchiola

    TiO2 is one of the most studied and understood metal oxide surfaces. It is also one of the most active photo-catalyst known. Its activity covers many typical chemical reactions including oxidation, dehydration, dehydrogenation and carbon coupling. For these reasons it has become a prototype surface for many relevant studies related to biomaterials, environmental remediation and photo-catalysts. In this talk we will cover the processes of adsorption and reaction of model surfaces of TiO2 and compare them to real catalytic materials for some of the above mentioned reactions with emphasis on photoreaction for H2 production from renewables.

  117. Chemistry Department Seminar

    "From Oscillation to Modulation: Dynamic Structural Changes in Catalysts with Sub-Second XAS"

    Presented by Dr. Maarten Nachtegaal, Paul Scherrer Institute, Villigen, Switzerland

    Tuesday, April 12, 2011, 10 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Jose Rodriguez

    The directed development of new catalysts necessitates the understanding of the structure – performance relation. Such relations can only be derived when the structure of a catalyst is determined under catalytically relevant conditions, using, for example, synchrotron-based XRD, XAS, and XES to determine the electronic and geometric structures in combination with a quadrupole mass spectrometer or gas chromatograph to determine the performance. Identifying the relevant structure, e.g. that of the reactive intermediate and / or a surface species poses a real challenge. Many important structural changes in catalysts, such as oxidation-reduction and structural re-ordering, occur in the sub-second to minute range. In this talk, I will show how sub-second XAS, as installed at the SuperXAs beam line at the Swiss Light Source, enables to identify the relevant structure of a catalyst and to identify active surface species. The first example is that of one of the most studied reactions in catalysis: carbon monoxide oxidation on the surface of a supported Pt catalyst. Using sub-second, spatially-resolved XAS, we followed the oscillating CO oxidation at different positions in a plug-flow reactor. We identified a short lived intermediate, when switching between the non active, surface poisoned metallic phase and the active partial oxidic phase that shines new light on the oxidation mechanism in CO oxidation in a packed-bed reactor. The second example deals with the application of modulation spectroscopy to XAS to identify small changes in catalyst structure which belong to the 'active' surface atoms of the catalyst. In modulation spectroscopy, the catalyst’s structure is modulated between two states by periodically changing, for example, the gas composition and collecting XAS spectra with a high repetition rate. After demodulation, spectra are obtained that are filtered from all contributions that do not change with the modulation frequency, which ar

  118. Chemistry Department Colloquium

    "Surface Coordination Chemistry Based On Redox-Active Complexes Toward Molecular Devices"

    Presented by Prof. Masa-aki Haga, Chuo University, Tokyo, Japan

    Monday, March 14, 2011, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Etsuko Fujita

    The bottom-up approach to functional nanoscale architectures from molecular components at the surface is the fundamental subject of nanochemistry. Controlling the molecular orientation and alignment on the surface plays an important novel for the surface functionalization. Recently, we have synthesized redox-active Ru/Os complexes bearing tetrapod phosphonate anchors, which acts as not only a electron reservoir but also a linker to bind another molecule units. Using these redox-active Ru/Os complexes as a molecular component, we successfully fabricated a series of multilayer structures with different potential gradient, which can be applied for the functional molecular devices such as photoelectrochemical cells and memory cells. We will also present an electronic conductivity of the molecular ensembles on the surface and the placement of nanomaterials such as DNA and nanoparticles.

  119. Chemistry Department Colloquium

    "Direct Imaging Studies of Atmospheric Photochemistry: From Energetics to Roaming Dynamics"

    Presented by Dr. Simon North, Chemistry Department, Texas A&M University

    Wednesday, March 9, 2011, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Greg Hall

    A detailed understanding of the photochemistry of radical intermediates is critical for accurate modeling of the atmosphere. Our work seeks to establish quantitative trends in the wavelength dependent photochemistry to aid in assessing atmospheric significance. Our group utilizes molecular beam velocity-map ion imaging to study the photodissociation of isolated, jet-cooled, radicals of relevance to atmospheric chemistry. The technique permits direct determination of final products, the distribution of excess energy, and accurate energetic. Careful analysis of the data can also reveal the underlying molecular choreography during the reaction. This presentation will highlight recent results on several target species including halogen oxides and the nitrate radical (NO3) that have been investigated at Texas A&M University.

  120. Chemistry Department Seminar

    "Lead in Water: Roles of Pb(II) and Pb(IV) Species and Formation of Intermediates and Radical Species in Electrochemical and Halogen-Driven Oxidations"

    Presented by Prof. Gregory V. Korshin, Department of Civil and Environmental Engineering, University of Washington, WA

    Tuesday, February 22, 2011, 10:30 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Kotaro Sasaki

    Lead is one of the most toxic and ubiquitous contaminants present in drinking water. Recent studies have shown that halogens species such as chlorine and chloramine are intimately involved in controls of lead release due to their effects on the formation of lead dioxide. When stable, PbO2 tends to suppress plumbosolvency but its destabilization by environmentally-relevant reductants can cause very high rates of lead release. Examination of the fundamental mechanisms of lead dioxide deposition and reduction shows that the electrochemical oxidation of Pb(II) proceeds via two distinct intermediates that correspond to a hydrodynamically mobile Pb(III)* species and a mixed Pb(II)/Pb(IV) complex that undergoes incorporation into growing nano-size PbO2 nuclei. Pb(II)/Pb(IV) intermediate is also formed upon the reduction of lead dioxide. The electrochemical oxidation of Pb(II) appears to be critically affected by OH• radicals whose generation at the electrode surface is catalyzed by PbO2 itself. Similar processes were in chlorine oxidations of Pb(II) hydroxide and (hydroxo)carbonates typical for environmental conditions. Further details and implications of these results will be discussed at the seminar.

  121. Chemistry Department Seminar

    "Combining reaction kinetics, spectroscopy and DFT calculations for mechanistic studies in heterogeneous catalysis"

    Presented by Prof. Simon Podkolzin, Dept. of Chemistry Engineering & Materials Science, Stevens Institute of Technology, Hoboken, NJ

    Wednesday, February 16, 2011, 11 am
    Room 300 - Chemistry Bldg. 555

    Hosted by: Dario Stacchiola

  122. Chemistry Department Seminar

    "Electron Transfer Mechanisms at SAM-Modified Electrodes: Impact of Complex Environments (Protein and RTIL)"

    Presented by Prof. Dimitri Khostariya, Research Director, Institute for Biophysics and Bionanosciences, I. Javakhishvili Tbilisi State University, Tbilisi, Georgia

    Thursday, January 27, 2011, 2:30 pm
    Room 300, Chemistry Bldg. 555

    Hosted by: James Wishart

  123. Chemistry Department Seminar

    "Computational Modeling of Carbohydrate Recognition Process in Selection"

    Presented by Toyokazu Ishida, AIST, Tsukuba, Japan

    Monday, January 24, 2011, 1:30 pm
    Room 300, Chemistry Bldg. 555

    Hosted by: James Muckerman

  124. Chemistry Department Seminar

    "Block Copolymer Membrane with Well Defined Transport Channels"

    Presented by Prof. Tomokazu Iyoda, Tokyo Institute of Technology, Japan

    Friday, December 3, 2010, 11 am
    Bldg. 555, Room 300

    Hosted by: John Miller

  125. Stony Brook University and Chemistry Department Student Poster Session

    Friday, November 12, 2010, 2 pm
    Chemistry Bldg. 555 Lobby

    Hosted by: Mike White and Jiangyong Jia

  126. Chemistry Department Seminar

    "The Hunt for Advanced Electrolyte Materials: A case Study of Doped Ceria"

    Presented by Pratik Dholabhai, Arizona State University

    Tuesday, November 9, 2010, 11 am
    Bldg. 555, Room 300

    Hosted by: Hua-Gen Yu

    Solid oxide fuel cells (SOFCs) are an energy user's dream: an efficient, combustion-less, virtually pollution-free power source, and promising enough for both stationary and mobile applications. Identifying the best electrolyte material is imperative for the development of next generation SOFCs. Doped ceria is recognized as one of the most promising solid electrolyte materials for the operation of SOFCs in the intermediate temperature range. We have developed an innovative simulation approach comprising a blend of first-principles calculations and kinetic lattice Monte Carlo (KLMC) modeling to predict the optimal composition of doped ceria that exhibits maximum ionic conductivity, a critical aspect involved in designing the finest electrolyte materials. The KLMC model uses the database of activation energies for defect migration in ceria and aliovalently doped ceria calculated within the framework of density functional theory (DFT+U). Results pertaining to the activated vacancy mechanism, favorable oxygen vacancy formation sites and preferred vacancy migration pathways in these materials will be elaborated. Since the first-principles calculations revealed significant vacancy-vacancy repulsion, we have conducted KLMC simulations with and without a repulsive interaction between the charged species. Details of KLMC model will be elucidated and the rationale behind the calculated maximum in ionic conductivity as a function of dopant concentration using two separate models will be discussed. Overall, due to its fundamental nature and reasonable agreement with experiment, this model demonstrates the possibility that it can be used as a design tool to predict novel ceria based electrolyte materials. Briefly, results of first-principles based electronic structure calculations depicting the interaction of hydrogen and water with (0001) surface of americium will be presented.

  127. Chemistry Department Seminar

    "Part 1: Solar hydrogen production from water using photocatalysts and photoelectrodes. Part 2: Development of new Ru dyes for dye sensitized solar cell. CO2 fixation: Interconversion between CO2/H2 and HCO2H) using Ir complexes"

    Presented by Drs. Kazuhiro Sayama & Yuichiro Himeda, NIAIS

    Friday, November 5, 2010, 10 am
    Chemistry Bldg. 555 - Room 300

    Hosted by: Etsuko Fujita

  128. Chemistry Department Seminar

    "Vibrationally Enhanced Associative Photodesorption of H2(D2) from Ru(0001): Quantum and Classical Approaches"

    Presented by Dr. Tijo Vazhappilly, University of South Carolina

    Thursday, November 4, 2010, 11 am
    Bldg. 555, Room 300

    Hosted by: Hua-Gen Yu

    This work investigates the femtosecond laser induced associative photodesorption of hydrogen, and deuterium from a Ruthenium metal surface. Many interesting features of this reaction were explored by experimentalists: (i) a huge isotope effect in the desorption probability of H2 and D2, (ii) the desorption yield increases non¬linearly with the applied visible laser fluence, and (iii) unequal energy partitioning to different degrees of freedom. These peculiarities are due to the fact that an ultrashort vis pulse creates hot electrons in the metal. These hot electrons then transfer energy to adsorbate vibrations which leads to desorption. This means that, surfaces introduce additional channels for energy exchange which makes the control of surface reactions more difficult than the control of reactions in the gas phase. One of the goals of the present work is to suggest, on the basis of theoretical simulations, strategies to control/enhance the photodesorption yield. For this purpose, we suggest a hybrid scheme to control the reaction, where the adsorbate vibrations are initially excited by an infrared (IR) pulse, prior to the vis pulse. Both adiabatic and non¬adiabatic representations for photoinduced desorption problems are employed here. 1 T. Vazhappilly, T. Klamroth, P. Saalfrank, R. Hernandez, J. Phys. Chem. C 113, 7790(2009). 2 T. Vazhappilly, S. Beyvers, T. Klamroth, M. Luppi, P. Saalfrank, Chem. Phys. 338, 299(2007).

  129. Chemistry Department Seminar


    Presented by Pradyumma S. Singh, Delft University of Technology

    Friday, October 8, 2010, 11 am
    Chemistry Bldg. 555, Room 300

    Hosted by: John Miller

    Electrochemical experiments in small confined volumes presents an interesting avenue to explore fundamental questions regarding the behavior of ions and redox-active molecules in solution in the vicinity of an electrode. These studies are also vitally important for development of lab-on-a-chip type applications which rely on electro-chemical detection. Using microfabrication methods we have developed electrochemical devices that con¬sist of two plane-parallel electrodes that are embedded in a nanofluidic channel. The electrode spacings can be reliably adjusted during the fabrication process to be ∼ 50 nm. The volume enclosed by the active area of the device is ca. 1 femtoliter (10−15 L). Redox-active molecules are capable of freely diffusing in and out of the nanochan¬nel. When the electrodes are suitably biased, the molecules can repeatedly shuttle multiple electrons between the electrode, leading to an amplification in the measured electrical current. Because of the small volume of the detection area, statistical fluctuations in the number of molecules in it give rise to corresponding fluctuations in the measured current which can be readily observed as electrical noise. As the absolute number of molecules decreases with decreasing detection volume, these fluctuations become an increasingly prominent feature in nanoscale devices. We recently introduced a new technique called Electrochemical Correlation Spectroscopy (ECS). Much like its optical counterpart, Fluoresence Correlation Spectroscopy (FCS), ECS relies on an autocorrelation analysis of these fluctuations. This yields new information about ad¬sorption dynamics of molecules in the channel, hitherto unavailable through other electrochemical means -a direct consequence of performing electrochemical experi¬ments in such small volumes. Recently, we have also been able to detect fluctuations corresponding to th

  130. Chemistry Department Colloquium

    "Design of Bimetallic Catalysts for Hydrogenation and Reforming Reactions"

    Presented by Jingguang G. Chen, University of Delaware, Center for Catalytic Science and Technology, Dept. of Chemical Engineering

    Tuesday, September 21, 2010, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Alex Harris

    It is well known that bimetallic catalysts often show novel properties that are not present on either of the parent metal surfaces. However, it is difficult to know a priori how the chemical properties of a particular bimetallic surface will be modified relative to the parent metals. In the past few years our research group has investigated the novel catalytic properties of various bimetallic systems, using a combination of Density Functional Theory (DFT) modeling, surface science studies on single crystal surfaces, and reactor evaluations of supported bimetallic catalysts [1-3]. In the current presentation we will use several probe reactions to demonstrate the unique chemical and catalytic properties of bimetallic surfaces. We will use the hydrogenation of alkenes, which is a reaction that requires relatively weak bonding of atomic hydrogen and alkenes, to demonstrate the utilization of bimetallic surfaces to enhance the hydrogenation activity; we will also use the selective hydrogenation of the C=O bond in unsaturated aldehydes to illustrate the possibility of controlling the selectivity with bimetallic surfaces [4]. Next, we will present results for controlling the activity and selectivity of bimetallic surfaces for the reforming of oxygenates (alcohols and glycols) and dehydrogenation of ammonia [5], which represent reactions that require relatively strong bonding of adsorbatess. Finally, we will present thermodynamic stability and kinetic measurements to enhance the stability of bimetallic catalysts by replacing one of the metal components with carbides [6,7]. Overall, these results demonstrate the possibility of selecting catalytic materials with desirable activity, selectivity and stability based on combined DFT predictions, surface science verifications and reactor evaluations. [1] Hwu et al. J. Am. Chem. Soc. 124 (2002) 702 [2] Kitchin et al. Phys. Rev. Lett. 93 (2004) 156801 [3] Chen et al. Surf. Sci. Reports, 63 (2008) 201 [4] Murillo

  131. Chemistry Department Colloquium

    "Photo-Induced Chemical Bond Formation In Fluid Solution and at Sensitized TIO2 Interfaces"

    Presented by Gerald J. Meyer, John Hopkins University

    Wednesday, September 15, 2010, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dmitry Polyanskiy

    Photo-initiated reactions that form chemical bonds are important for the conversion and storage of solar energy. Iodide oxidation yields an I-I bond that is key to sensitizer regeneration in dye-sensitized solar cells. The detailed mechanism(s) by which iodide oxidation yields the I-I bonds present in I2-• and I3-remain speculative. Here direct evidence that metal-to-ligand charge transfer (MLCT) excited states can directly yield iodine atoms that subsequently react to form I-I chemical bonds, kinetic and thermodynamic data are summarized in the Eo = -0.82 RuII/+(bpz)2+ Scheme 1 Jablonski-type diagram shown in Scheme 1. The Eo = +0.82 RuII(bpz-)+, I2 kcr = 2.1 ± 0.3 × 1010 M-1 s-1 compound [Ru(bpz)2(deeb)](PF6)2, where bpz is - 2 I¬ RuII(bpz-)+, I3-+ I¬- kI2 = 3.3 × 109 M-1 s-1 + I2× 2,2-bipyrazine and deeb is 4,4’-(CO2Et)2-2,2’-bpy = 1.75 s V vs SCE is abbreviated Ru(bpz)2+. Excited state electron - + I--1 kI = 2.4 ± 0.2 × 1010 M-1 s transfer to yield the iodine atom is favored by 430 Eo = +0.93 RuII(bpz-)+, I mV. Reaction of the iodine atom with iodide to + I ¬ ket = 6.5 ± 0.3 × 1010 M-1 s-1 RuII*/+(bpz-)2+* make an I-I bond lowers the free energy stored by 110 mV. Charge recombination to yield ground state products, Ru+ + I2-•  RuII + 2I- is downhill (-Go = 1.64 eV) and occurs with a rate constant of 2.1 x 1010 M-1 s-1, almost ten times larger than the I2-• disproportionation rate constant. Unwanted recombination to I2-• has been proposed to lower the efficiency of dye-sensitized solar cells and this data shows that it can be a very fast reaction [1]. Rapid photo-induced electron injection into TiO2 and regeneration by a donor, D, such as iodide or phenothiazine, yields sensitizers in an environment distinctly different from that prior to light absorption. Spectroelectrochemical measurements indicate that the injected electron influences the absorption spectr

  132. Chemistry Department Seminar

    "Controlling Clustering and Rheology in Attractive Nanoparticle Dispersions"

    Presented by Surita Bhatia, University of Massachusetts Amherst

    Thursday, September 9, 2010, 10 am
    CFN Building 735 - Room B

    Hosted by: Alex Harris

    NOTE: Seminar will be held in CFN Building 735 - Room B. Recently, there has been increased interest in the controlled formation of dense, micron-sized nanoparticle clusters for a variety of applications, including digital printing, cellular imaging, and targeted therapies. Creating such assemblies via controlled aggregation of primary particles that are nanoscale, rather than direct synthesis of micron-sized particles structures, is desirable because a high degree of functionality can be incorporated onto the surface of each primary nanoparticle. The classic experimental and theoretical work on microstructure and aggregation kinetics of attractive colloids focuses on systems with short-range attractions that form fractal aggregates and gels. However, the physics of formation of dense clusters appears to be quite different, with dense microclusters occurring in systems with intermediate-range attractive forces. In this talk, I will discuss how the large-scale structure and rheology of attractive dispersions can be tuned via the strength and range of interparticle attractions. Two experimental systems will be described in detail: (i) spherical polystyrene particles with hydrophobically-modified polyacrylic acid chains attached to the surface, and (ii) a disk-shaped synthetic clay, Laponite®, with poly(ethylene oxide) chains that weakly adsorb to the surface. Small-angle and ultra small-angle neutron scattering (SANS and USANS) results suggest that the surface roughness of clusters increases with increasing strength of attraction. Moreover, the rheology of system (ii) displays interesting re-entrant behavior, whereby gels of Laponite® particles melt and decrease in viscosity as interparticle attractions increase. This phenomena, which may be related to particle clustering, enables processing of dispersions with high particle loadings.

  133. Chemistry Department Seminar

    "The AMFC: A Possible Key for Getting Platinum Out of the Fuel Cell"

    Presented by Dr. Shimshon Gottesfeld, Cellera, Inc., Israel

    Wednesday, August 18, 2010, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Radoslav Adzic

    The alkaline membrane fuel cell (AMFC) is a very recent arrival in the family of low temperature, polymer electrolyte fuel cells. It's uniqueness is in the combination of "no-platinum and no-liquid electrolyte". Shifting the inner pH of the membrane electrolyte up by 12-14 pH units, opens the door to the use of non-PGM catalysts as well as inexpensive metal hardware. Development over 2.5 years in a new start-up company targeting AMFC products will be described. As final subject, some aspects of electrocatalysis in alkaline media will be described. Because of the proprietary nature of some technical aspects, not all questions can/will be fully answered.

  134. Condensed-Matter Physics & Materials Science Seminar

    "Investigating the Internal Structure and Chemistry of a Dead Sea Scroll Parchment Fragment with Ink using Synchrotron X-ray Micro-beam Techniques"

    Presented by Bridget Murphy, University of Kiel

    Thursday, July 1, 2010, 1:30 pm
    Small seminar room, Bldg 510

    Hosted by: Ben Ocko

    For the 2000 year old Dead Sea Scrolls parchment degradation and conservation are key issues. Since the find, the scrolls have rapidly become more brittle and difficult to read. However, the mechanism of the degradation processes is still not understood. Using complementary synchrotron-based X-ray micro-beam techniques ancient parchment is compared with modern. Micro X-ray fluorescence and infra-red spectroscopy show that the tanning or liming procedure provides an effective protective layer for the scrolls and that it is likely that the ink and binder in turn act as a fixer for the protective Ca layer. Synchrotron-based computed micro-tomography visualisation of ancient fragments similarly indicates that delamination originates in the centre of the parchment and not at the outside as originally expected. In the degraded region a strong signal from the protein amide 1 band observed with infra-red spectroscopy showing that despite the disentanglement the collagen fibre matrix is well preserved.

  135. Chemistry Department Colloquium

    "Sun, Water, Hydrogen: from micro-algae to nanostructured electrocatalytic nanomaterials"

    Presented by Vincent Artero, University of Grenoble, France

    Friday, June 11, 2010, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Etsuko Fujita

    As far as hydrogen/water interconversion is concerned, a number of technological solutions such as those developed in proton-exchange-membrane fuel-cells or electrolyzers are based on the powerful catalytic properties of platinum metal. But this scarce and expensive metal itself is not a sustainable resource and its replacement by low cost and readily available materials is a requisite for these technologies to become economically viable. A competitive alternative to platinum should be found in living micro-organisms metabolizing hydrogen thanks to hydrogenases. Catalysis in hydrogenases only requires base-metal centers (nickel and iron) and we will show how their active sites can be used as an inspiration for the design of new synthetic catalysts for hydrogen production and oxidation.1,2 In addition, it is highly desirable to produce hydrogen from renewable resources such as water and solar energy as done by some natural micro-organisms thought a photosynthetic process. To work towards this end, we will show how we can take inspiration from microbes and algae to design noble-metal free electrocatalysts3-6 and photocatalysts7,8 that can be further grafted on nanostructured materials.9-11 References 1 Canaguier, S.; Artero, V.; Fontecave, M. Dalton Trans. 2008, 315-325. 2 Wilson, A. D.; Newell, R. H.; McNevin, M. J.; Muckerman, J. T.; DuBois, M. R.; DuBois, D. L. J. Am. Chem. Soc. 2006, 128, 358-366. 3 Baffert, C.; Artero, V.; Fontecave, M. Inorg. Chem. 2007, 46, 1817-1824. 4 Razavet, M.; Artero, V.; Fontecave, M. Inorg. Chem. 2005, 44, 4786-4795. 5 Jacques, P.-A.; Artero, V.; Pécaut, J.; Fontecave, M. Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 20627-20632 6 Canaguier, S.; Field, M.; Oudart, Y.; Pécaut, J.; Fontecave, M.; Artero, V. Chem. Commun. 2010, in press. 7 Fihri, A.; Artero, V.; Pereira, A.; Fontecave, M. Dalton Trans. 2008, 5567-5569. 8 Fihri, A.; Artero, V.; Razavet, M.; Baffert, C.; Leibl, W.; Fontecave, M. Angew. Chem. Int. Ed. 2008, 47, 564-56

  136. Center for Functional Nanomaterials Seminar

    "Single-Molecules in the Break Junctions: from conductance measurements to mechanochemistry"

    Presented by Young S. Park, Columbia University

    Thursday, May 27, 2010, 1 pm
    Conference Room B, Bldg. 735

    Hosted by: Barney Grubbs

    The development of molecular scale electronic devices requires the comprehension of electron transport properties through single-molecules. Using the scanning tunneling microscope (STM) based break-junction technique, we have systematically investigated the conductance behaviors of gold-molecule-gold junctions with a series of molecules. We screened various ligands and found that amines (-NH2), sulfides (-SMe), and phosphines (-PMe2, and -PPh2) give well-defined peaks in the conductance histogram. With these chemical functionalities, we could expand the scope of conductance study into conformational dependence and end group dependence. Our ongoing research is the synthesis of strained molecules that undergo isomerization under mechanical force to their less strained isomers. Please contact Barney Grubbs (; x2382) if you are interested in meeting with the speaker

  137. Chemistry Department Colloquium

    "Recent Developments in Electrochemistry Relevant to Ionic Liquids and Green Chemistry"

    Presented by Alan Bond, Monash University, Melbourne, Australia

    Wednesday, May 26, 2010, 11 am
    Chemistry Bldg. 555, Room 300

    Hosted by: John Miller

  138. Center for Functional Nanomaterials Seminar

    "Computational Chemistry Research in Catalysis and Nanoscience"

    Presented by Daniel Torres, Argonne National Laboratory

    Wednesday, May 12, 2010, 11 am
    Bldg. 735

    Hosted by: Mark Hybertsen

    The development of efficient future technologies for energy production and environmental protection is highly dependent on solving a large number of technical challenges in diverse areas. These range from identification of novel materials for gas capture or storage to optimization of heterogeneous catalytic materials. Meeting these challenges, in turn, requires a high level of knowledge of the structure and properties of materials at the atomic level. In this talk, I will review my latest work aimed at generating such knowledge, focusing in particular on the fundamental understanding of chemical and physical processes involved in atomic-scale catalysis. First, I will address the question of selectivity in heterogeneous catalysis. By means of two different examples, the partial oxidation of double bonds and the hydrogenation of triple-bonded compounds in an alkene stream, I will illustrate how atomistic modeling can contribute substantially to the understanding of applied heterogeneous catalysis. Second, I will provide a critical first step towards the study of spin-spin interactions on catalysis. Using methanation as a probe reaction, I will show by theoretical means that changes in the magnetic properties of ferromagnetic base metal catalysts can lead to clear and potentially measurable changes in their performance.

  139. Chemistry Department Colloquium

    "What Can Spectroscopy Tell Us About Nanoconfined Liquids"

    Presented by Ward H. Thompson, Chemistry Department, University of Kansas

    Wednesday, April 28, 2010, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Robert Crowell

    There is currently significant interest in the properties of liquids confined on nanometer length scales. In addition to their usefulness in understanding fundamental properties of liquids at interfaces, they are relevant to a variety of potential applications of mesoporous materials, such as catalysis and separations. The nanoscale confinement of a liquid can significantly affect both its equilibrium and dynamic properties, but probing these changes spectroscopically can be challenging. In particular, a better understanding of what molecular-level information is contained in the results of spectroscopic measurements is needed. This issue will be examined through the use of molecular dynamics simulations of spectroscopic results and comparisons with corresponding experimental measurements.

  140. Center for Functional Nanomaterials Seminar

    "Probing the Nanoscale Surface Chemistry, from UHV through Ambient to Liquid"

    Presented by Peng Jiang, Lawrence Berkeley National Laboratory

    Monday, April 26, 2010, 10 am
    Bldg 735, Conference Room A

    Hosted by: Peter Sutter

    The modern chemical industry uses heterogeneous catalysts in nearly all production lines. With the rapid growing demand for renewable and green energy, catalysts are attracting more and more attention for efficient and environmental benign chemical reactions. In this talk, I will present our recent advances in several model systems by means of different surface characterization methods, which can cover UHV, ambient and aqueous conditions. These studies will help bridge the pressure gap between UHV surface science studies and realistic conditions in heterogeneous catalysis.

  141. Chemistry Department Seminar

    "Tuning the Optical Properties of Single Gold Nanoparticles"

    Presented by Alison Funston, The University of Melbourne, Victoria, Australia, Australia

    Tuesday, November 24, 2009, 10:30 am
    Room 300, Chemistry Bldg. 555

    Hosted by: John Miller

    The interaction of electromagnetic light waves with metallic conductors causes free electrons on the surface of the metal to oscillate in resonance with the light wave. These waves are known as surface plasmons. Miniaturization of the metal to form nanocrystals with dimensions less than 100 nm results in the spatial confinement of the conduction electrons within the particles and a localised surface plasmon resonance (LSPR). It is the LSPR which gives rise to the intense colours of such particles. The resonance energy is highly sensitive to the size and morphology of the particle and by tailoring the shape of the particles it becomes possible to tune the optical properties of the material across the visible and NIR spectrum. In addition to the passive control of the resonance energy via changes to the particle size or shape, more active control is possible and leads to a large number of possibilities for the use of metal nanoparticles as sensors and within optoelectronic applications. These methods include control of the nanoparticle environment, the electronic charge of the particle as well as the interparticle spacing. In this presentation the manipulation of the energy of the LSPR of single gold nanoparticles using the above methods will be shown. These single particle investigations have been extended to allow for the detection of electron transfer reactions on single particles. Some examples include Au catalysed electron transfer processes, the growth of single gold nanorods (detected in situ), and the electrochemical charging of gold nanorods. The rate and number of electrons transferred (or atoms reacting) may be directly obtained from the energy shift of the plasmon resonance with time. The interaction of two or more closely spaced metal nanoparticles also leads to changes in the energy of the surface plasmon resonance. The interparticle coupling and thus plasmon energy may be controlled through the interaction geometry as well as nanoparticle separat

  142. Chemistry Department Seminar

    "Chemical Engineering Applications of Electrochemistry at Columbia University"

    Presented by Alan West, Columbia University

    Thursday, October 1, 2009, 11 am
    Room 300, Bldg. 555

    Hosted by: Alex Harris

    A brief overview of the research interests of the Chemical Engineering Department of Columbia University is presented. Our research program, centered on chemical engineering applications of electrochemistry, is discussed in more detail. After outlining the focus of current projects in the group, the electrodeposition of copper wires that serve to connect transistors on advanced logic chips is discussed. The width of the smallest wires will approach 20 nm in the next few years. Based on an understanding of reaction mechanisms, it is possible to design electrolytes that enable successful, defect-free plating of these smallest features. The multi-scale nature of the design constraints is also demonstrated through transport considerations that are relevant on the scale of the entire wafer (300 mm). In both examples, we emphasize the role of surface-active organic additives on the nucleation and growth of copper.

  143. National Synchrotron Light Source Lunch Time Seminar

    "Elemental Trends in Ocean Chemistry, Revealed by Synchrotron Microprobe of Echinoderms"

    Presented by Aaron Frodsham, Stony Brook University

    Friday, September 18, 2009, 12 pm
    Seminar Room, Bldg. 725

    Hosted by: Christie Nelson

  144. Chemistry Colloquium

    "Catalysis by Atomic Sized Centers"

    Presented by Dr. Horia Metiu, University of California, Dept. of Chemistry & Biochemistry

    Wednesday, September 16, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Ping Liu

    We perform density functional calculations to explore the properties of two new classes of catalysts, both consisting of atomic-size active centers. In one class the cation at the surface of an oxide is replaced with another cation which we call a dopant. By an appropriate choice of the dopant-oxide pair we can weaken the bond of the oxygen atoms at the surface of the oxide and make the system a better oxidant and a better oxidation catalyst. Other choices of dopant-oxide pairs will cause the dopant to adsorb oxygen and weaken the O-O bond to activate oxygen for oxidation reactions. A second class of catalysts with atomic-size active center consists of small oxide clusters supported on a different oxide (for example, a VO3 cluster supported on TiO2). Some of the oxygen atoms in the cluster end up bridging two different cations (for example, V-O-Ti) and if the two cations are well chosen, the bridging oxygen becomes active in oxidation reactions. We study the mechanism of methanol oxidation to formaldehyde by VO3 supported on TiO2 and plan to screen a large set of oxide clusters on an oxide for hydrocarbon activation.

  145. Chemistry Department Colloquium

    "Theories for Predicting Reversible Potentials of Reactions on Electrode Surfaces from Internal and Gibbs Energies: Applications to ORR"

    Presented by Dr. Alfred Anderson, Case Western Reserve University

    Wednesday, August 26, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Ping Liu

    Given a reduction in aqueous electrolyte with standard reversible potential Uo(aq): R(aq) + H+(aq) + e- ⇄ P(aq), (1) the corresponding description when reactant and product are adsorbed on the electrode is R(ads) + H+(aq) + e- ⇄ P(ads) (2) where R and P stand for reactant and product. We have found that when these species are adsorbed, the reversible potential Uo(ads) is given to good approximation by Uo(ads) = Uo(aq) + Do(P) – Do(R) (3) where Do are dissociation energies of the bonds to the surface. Using eq 3 for Uo(ads) has the advantage that it does not require calculating solvation energies of charged ions such as hydronium and hydroxyl because they are contained in Uo, which is available from measurement. For neutral reactants and products, solvation energies are small, allowing eq 3 to rapidly yield useful predictions based on energy calculations using available commercial codes. The full Gibbs energy change for a reduction reaction, including potential dependence, is given by ΔG(U) = {GRed(U) – GOx(U)} + n(φ + FU) (4) where -(φ + FU) is the energy of an electron on the vacuum scale, φ being the thermodynamic work function of the standard hydrogen electrode. We have developed a theory that fully implements eq (4) in a code called Interface 1.0. It uses two-dimensional density functional band theory for periodic systems with linear combinations of pseudo-atomic orbitals, norm-conserving pseudopotentials, and projector expansions. In it the surface potential is adjusted by adding surface charge and a counter charge distribution in the double layer is determined self-consistently using a modified Poisson-Boltzmann theory within a dielec

  146. Chemistry Department Seminar

    "Thermochemistry of the Metal Hydride Bond in Organometallic Tungsten Complexes, and Catalytic Oxidation of H2 by Ni Complexes"

    Presented by R. Morris Bullock, Pacific Northwest National Laboratory

    Friday, July 10, 2009, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: David Grills

  147. Chemistry Department Colloquium

    "New Ventures in Osmium, Rhodium, and Ruthenium Polypyridyl Chemistry"

    Presented by Elise Megeheee, St. John's College, Dept. of Chemistry

    Wednesday, July 8, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Jack Preses

  148. Chemistry Colloquium

    "Cluster Size-dependent Correlations Between Electronic Structure and Activity of Model Supported Palladium Catalysts"

    Presented by Scott Anderson, University of Utah, Chemistry Department

    Wednesday, June 17, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Alex Harris

    Size-selected model catalysts are prepared by deposition of mass-selected metal cluster cations on well characterized oxide supports. The model catalysts are characterized by x-ray photoemission spectroscopy (XPS), low energy ion scattering, and Auger electron spectroscopy. A variety of mass spectrometric methods are used to study chemical reactions catalyzed on the surface. Results for palladium clusters on alumina and titania will be present. In both cases, there are strong correlations between activity for CO oxidation and core level photoemission energies. The combination of ion scattering and XPS reveal the nature of the adsorbate bind sites, and the fate of the activated oxygen during reaction.

  149. Chemistry Colloquium

    "The Dynamics of Hydroxide Ion Transport in Water"

    Presented by Professor Andrei Tokmakoff, Massachusetts Institute of Technology, Dept. of Chemistry

    Wednesday, May 27, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Robert Crowell

  150. Chemistry Colloquium

    "Acid Dissociation at the Surfaces of Salty Glycerol and Water:"

    Presented by Professor Gilbert Nathanson, University of Wisconsin, Dept. of Chemistry

    Wednesday, April 29, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Gregory Hall

    Gas-liquid reactions occur widely in our lives, including processes in atmospheric aerosols, the commercial production of sulfuric acid, and gas transport at the air/lung interface. We have continually refined our molecular view of these interfacial interactions as new computational and experimental tools have become available. In this talk, I will describe gas-liquid scattering experiments between gaseous acids such HCI and protic solvents such as salty glycerol and salty water. These studies lead to a detailed picture of the ways in which impinging gas molecular bounce off, react, and dissolve in liquids. In particular, we identify an ultrafast DCI-HCI proton exchange at the surface of glycerol that is catalyzed by alkali halide salts. We have recently begun searching for this interfacial exchange reaction in cold salty water.

  151. Chemistry Department Seminar

    "Carbon Nanotubes as PEM Fuel Cell Catalyst Support"

    Presented by Dr. Yangchuan Xing, Missouri University of Science and Technology

    Wednesday, April 22, 2009, 11 am
    Room 300, Bldg. 555

    Hosted by: Radoslav Adzic

    Fuel cells are electrochemical devices that convert chemical energy directly into electricity in highly efficient and environmentally friendly processes. Although fuel cells were invented one and a half centuries ago, only recently have they become economically competitive with conventional power systems. Among various fuel cells, proton exchange membrane (PEM) fuel cells are expected to become a viable future power source due to their low operating temperatures, high power density, and rapid response to varying loads. Micro PEM fuel cells may also compete with lithium-ion batteries to provide long-lasting power for portable electronics. During the past two decades, enormous efforts have been made to advance PEM fuel cell technology. However, new materials are still in need to resolve some technical problems in PEM fuel cells before they can become a commercial power source. One material that has been actively explored in recent years is carbon nanotubes. In this talk, I will give an overview of carbon nanotube applications in PEM fuel cells. I will then present our work on functionalization of carbon nanotubes and preparation of catalyst nanoparticles on them. I will also present our work on the electrochemical durability of carbon nanotubes and new electrode design with carbon nanotube arrays.

  152. Chemistry Department Colloquium

    "Binding and Patterning of Organic Molecules on Silicon Surfaces"

    Presented by Gua-Qin Xu

    Thursday, April 16, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Jan Hrbek

    Attaching functional organic layers to silicon surfaces is emerging as one of the promising approaches in the development of new semiconductor-based microelectronic devices and biosensors. It provides opportunities for incorporating molecular recognition, chirality, chemical/biological sensing, light emission/detection and lubrication for various technological needs. Recent systematic investigations on chemical reactions of organic molecules on silicon surfaces clearly demonstrated that both Si(100) and Si(111)-7x7 can act as reagent-like substrates with a high reactivity for covalent binding of different classes of organic functionalities. Reaction mechanisms including [2+2]-cycloaddition, [4+2]-cycloaddition, dative-bonding, dissociation and ene-like reactions have been revealed and will be discussed, providing a molecule-level understanding on reaction mechanisms, chemical and surface-site selectivities at organic/silicon hybrid interfaces. In addition, new approaches for fabricating organic nanopatterns using self-assembled templates on silicon surfaces will be introduced, which can be useful in growing organic nanomaterials for developing nano- or molecular-scale devices.

  153. Brookhaven Lecture

    "448th Brookhaven Lecture: 'New Chemistry for Artificial Photosynthesis: A Theoretical Perspective'"

    Presented by James Muckerman, Ph.D., Chemistry Department

    Wednesday, April 15, 2009, 4 pm
    Berkner Hall Auditorium

    Hosted by: Brant Johnson & Stephen Musolino

    <p>Photosynthesis, which occurs in green plants, is a natural process in which light produces energy from water and carbon dioxide. Nowadays, scientists are working to replicate this process artificially, with the goal of creating clean, usable, renewable energy from the greenhouse gas carbon dioxide.</p> <p>During the 448th Brookhaven Lecture in Berkner Hall on Wednesday, April 15, at 4 p.m., Senior Chemist James Muckerman of the Chemistry Department will discuss "New Chemistry for Artificial Photosynthesis: A Theoretical Perspective." After reviewing natural photosynthesis, he will discuss how electrochemical systems driven by sunlight could carry out artificial photosynthesis and how these systems could then be turned into usable fuels that do not create pollution or undesirable by-products</p> <p>James Muckerman earned his Ph.D. in physical chemistry from the University of Wisconsin in 1969. He joined BNL's Chemistry Department as an associate chemist in 1969 and, moving up the ranks, was awarded tenure in 1975 and promoted to senior chemist in 1986. Within Chemistry, he served as assistant chair, 1988-90, and associate chair, 1990-93. Six years ago, Dr. Muckerman changed his research focus from gas-phase chemical physics to renewable energy, working to advance the theory behind a number of the U.S. Department of Energy's energy initiatives.</p> <p>To join the speaker for supper at an off-site restaurant after the lecture, make your reservation with Jean Petterson, or Ext. 4302.</p>

  154. Chemistry Department Seminar

    "PEM-Based Water Electrolysis for Current and Future Hydrogen Markets: Research Advances and Challenges"

    Presented by Katherine Ayers, Proton Energy Systems

    Tuesday, April 14, 2009, 10:30 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Alex Harris

    Proton Energy Systems is the world's leading suppliers of onsite hydrogen generators utlizing PEM technology, with over 1400 commercial electrolyzers in the field and outputs up to 12 kg/day of hydrogen. The current stack design, which generates hydrogen at differential pressures of 200-400 psi, has demonstrated safe and reliable performances over tens of thousands of hours of operation. Current research efforts focus on a) efficiency and cost improvements for today's applications, b) development of larger cell stacks and systems for fueling applications up to 100 kg/day, and c) design of higher pressure cell stacks from 2400 to 5000 psi differential pressure for backup power applications. Progress to date includes an almost 20% improvement in efficiency in stack performance, while cost reduction efforts for the cell stack membrane-electrode-assembly (MEA) have netted nearly a 30% savings in MEA material cost. This is significant considering MEA represents the single highest cost component within the electrochemical stack. This talk will focus recent materials leading to these achievements and research challenges for the future.

  155. Biology Department Seminar

    "Novel Metallochemistry in Zinc Transporters: Integration of Structural, Functional and Computational Analyses"

    Presented by Dax Fu, BNL Biology Department

    Thursday, March 19, 2009, 11 am
    John Dunn Seminar Room, Bldg. 463

    Hosted by: Bob Sweet

    Metal transporters use unique coordination chemistry to move metal ions across the membrane. The metallochemistry of metal transporters is fundamentally distinct from that of metalloenzymes where metal ions are bound tightly as integral parts of the protein structures. Metal transporters selectively bind metal ions and translocate them against concentration gradients. The binding affinity of metal transporters is much lower than expected for equilibrium metal binding in cells, while the timescale of metal transport is millisecond, vastly faster than many metalloproteins that typically take hours to release bound metal ions. The current conceptual framework of metallochemistry is inadequate to explain how metal transporters acquire metal ions against thermodynamic gradients while maintaining rapid metal mobility, yet extraordinary selectivity over similar metal ions. Therefore, metal transporters provide a unique research opportunity for making paradigm-shifting discoveries at the interface of biochemistry and metallochemistry. I will present the structure of a zinc transporter YiiP and discuss how zinc coordination chemistry is tailored to distinct functions in a membrane transporter.

  156. Chemistry Department Seminar

    "Nano-Scale Environmental Effects on the Reactivity of Platinum Clusters"

    Presented by Ye Xu, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory

    Wednesday, March 11, 2009, 11 am
    Room 300, Bldg. 555

    Hosted by: Alex Harris

    Advances in synthesis techniques for size-defined metal clusters have brought uniform and potentially size-tunable nano-catalysts closer to reality. The versatility of platinum catalysts in many important industrial and energy applications and the high cost of the metal make Pt an excellent candidate for going “nano.” However, the response of such tiny objects to the chemical environment will need to be thoroughly understood before this type of novel catalyst can be productively deployed. The ability of theory and computational modeling to elucidate the properties of objects in the angstrom size regime makes it an ideal tool for nano-catalysis research. Therefore we have performed density functional theory calculations to explore the interaction of a series of small Pt clusters with prototypical environmental elements. Non-bulk-like, size-dependent phase behavior and accompanying changes in the molecular and electronic structures are identified for the isolated clusters when they are exposed to an oxygen atmosphere, and size- and composition-dependent reactivity is found for two model oxidation reactions, CO and NO oxidation. In addition, we have investigated how adsorption on a MgO(100) support surface affects the structures and oxidation of the Pt clusters and analyzed the mechanism of adhesion. Our results shed light on the intricate coupling between particle size, chemical environment, and reactivity in the surface chemistry of finite supported metal clusters.

  157. Chemistry Department Seminar

    "Structure and Dynamics of Molecules at the Air/Water Interface"

    Presented by Dr. Yi Rao, Department of Chemistry, Columbia University

    Thursday, March 5, 2009, 11 am
    Room 300, Bldg.555

    Hosted by: Nicholas Camillone

    Sum Frequency Generation (SFG) has been utilized to investigate structure and dynamics of molecules at the air/water interface. The talk includes two parts. The first part is acid-base reaction at the air/water interface. We demonstrate that phenol as well as organic ion-phenolate can stay at the air/water interface. The pKa of phenol is higher than that in bulk. In the second part, molecular motion and electron transfer at the air/water interface will be introduced. With SFG the time dependent changes in the orientational motions of vibrational chromophores in interfacial molecules are obtained. The chromophores are the carbonyl group and the CF3 group, both in the coumarin 153 molecule at the interface. The orientational relaxation time of the C=O axis is slightly faster than that of the CF3 axis, with both however being much faster than that of the orientational relaxation of the coumarin molecules permanent dipole moment axis with respect to the surface normal. These interfacial results are compared with our measurements of the orientational relaxation of C153 in bulk water. The dynamics of excited state electron transfer at the air/water interface between photoexcited coumarin 314 (C314) serving as the acceptor and Dimethyl-aniline (DMA) as the donor, using the SFG probe that is resonant with the carbonyl chromophore of C314. The dynamics are compared with bulk electron transfer dynamics will be presented.

  158. Chemistry Colloquium

    "Electrochemical Atomic Layer Deposition (ALD)"

    Presented by Professor John Stickney, University of Georgia, Dept. of Chemistry

    Wednesday, March 4, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Miomir Vukmirovic

    Recent results in studies of the formation of compound and metal nanofilms by electrochemical atomic layer deposition (ALD) will be discussed. ALD is the deposition of materials an atomic layer at a time using surface limited reactions. Electrochemical surface limited reactions are generally referred to as underpotential deposition or UPD. By combining UPD and ALD, electrochemical ALD is created. Historically most electrochemical ALD has been performed in the creation of compound semiconductor thin films. More recently a number of elemental deposits have been formed by electrochemical ALD, and a surface limited reaction referred to here as a surface limited redox replacement or SLRR. Recent work on the formation of compound for photovoltaics, thermoelectrics, and for phase change memory may be discussed. In addition, recent work on the growth of Pt and Ru nanofilms for fuel cell electrodes may be described. Deposit characterization involves electron beam microprobe analysis (EPMA) for deposit stoichiometry. Glancing angle X-ray diffraction for structural characterization, while scanning tunneling microscopy (STM) was used to characterize the surface morphology. Optical characterization involves reflection absorption studies as well as photoelectrochemical studies. Optimization studies involve systematic investigation of the conditions which result in the formation of one compound or elemental monolayer with each deposition cycle. In general, deposits formed at a rate of one monolayer per cycle or less show the best structure, stoichiometry and morphology. Nano templates can be used to form nanoclusters, rods or wires, depending on the number of cycles performed. Superlattices can be formed by alternating some finite number of cycles for the growth of one compound with a similar number of cycles of another. X-ray diffraction can then be used to characterize the period of the superlattice.

  159. Chemistry Colloquium


    Presented by Paul Barbara, University of Texas at Austin

    Wednesday, February 25, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: John Miller

    The complex charging/discharging dynamics of conjugated polymers were investigated and unravelled by a variety of single molecule fluorescence spectroscopy electro-optical techniques see Fig. 1. The injection of positive charge carriers (holes) into conjugated polymer chains is a critical process in solar cells based on organic materials and organic/inorganic hybrid materials. We have observed that hole injection into single conjugated polymer chains is light-assisted and highly cooperative. This unprecedented effect may underlie critical, poorly understood organic electronic device phenomena such as the build-up of functional deeply-trapped-charge layers in polymer light emitting displays and the poor fill factors in organic photovoltaic devices. (Fig. 1. (A) Hole-injection device structure. (B) HOMO energy levels relative to the work function of the hole-injection electrode for the device shown in A. The black and red lines are Poisson-Boltzmann simulations at 0V (at equilibrium) and 10V (before charging) respectively. (C) single-molecule fluorescence-intensity trajectories (D) Ensemble average of ~100 single-molecule normalized fluorescence-intensity trajectories obtained while applying a triangular bias (top green line) (E,F) Ensemble average of ~100 single-molecule F-V trajectories obtained at: high vacuum (10-7 Torr) (E) and 5 Torr of O2 (F). ) The hole-injection from a layer of carbazole (a strong organic hole-donor), into isolated, single polymer chains of the conjugated polymer (MEH-PPV) imbedded in a multilayer device (Fig 1A) was studied. The experimental amount and rate of hole-injection from the carbazole HTL into individual polymer chains was monitored indirectly by single molecule fluorescence spectroscopy. We assign the injection of holes reported herein to a previously unreported light-induced hole transfer mechanism (denoted by LIHT) involving light assisted injection of holes from the carbazole layer into single MEH-PPV polymer chai

  160. Chemistry Department Colloquium

    "Lithium Battery - Next Generation of Power Source for Electric Vehicles"

    Presented by Xiao-Qing Yang, Brookhaven National Laboratory

    Wednesday, February 11, 2009, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dr. Radoslav Adzic

  161. Chemistry Colloquium

    "Unlocking the Secrets of Light-Driven Water Oxidation: Snapshots of Biological Proton-Coupled Electron Transfer in Photosystem II*"

    Presented by Professor K. V. Lakshmi, Rensselaer Polytechnic Institute, Dept. of Chemistry and Chemical Biology

    Friday, December 12, 2008, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: James Muckerman

    The solar water-splitting protein complex, photosystem II (PSII), catalyzes one of the most energetically demanding reactions in Nature by using light energy to drive the catalytic oxidation of water. Proton-coupled electron transfer (PCET) reactions, which are exquisitely tuned by smart protein matrix effects, are central to this water-splitting chemistry. PSII contains two symmetrically placed tyrosine residues, YD and YZ, one on each subunit of the heterodimeric core. The functions of these symmetry-related tyrosines are quite distinct, a versatility provided by their distinct local environments in PSII. YZ is kinetically competent and has been proposed to be directly involved in the PCET reactions of water oxidation. In contrast, the YD PCET redox poises the catalytic Mn4 cluster and may electrostatically tune the adjacent monomeric redox-active chlorophyll and -carotene in the secondary ET pathway of PSII. We have developed novel EPR methods for the study of powder and oriented PSII complexes to elucidate the geometry of the Mn4 cluster and the redox-active tyrosine, YZ, in the S2YZ• intermediate state of PSII. The structural model from these studies indicates proton-coupled electron-transfer between YZ and a water ligand to the Mn4 cluster. We are developing pulsed X-band (9 GHz) and high-frequency D-band (130 GHz) electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) methods to disentangle the individual steps of photo-induced PCET that leads to the formation of the redox-active tyrosyl radicals, YD• and YZ•, in PSII. We provide direct ‘snapshots’ of functional PCET intermediates and, for the first time, make it possible to detail the mechanism of PCET in photosystem II. *This research is supported by U. S. Department of Energy, Basic Energy Sciences, Solar Energy Utilization Program (DE-FG02-0ER06-15).

  162. Chemistry Department Seminar

    "Applications of a Combined UHV and Electrochemistry System in Electrocatalysis"

    Presented by Weiping Zhou, Brookhaven National Laboratory, Chemistry Dept.

    Thursday, November 20, 2008, 11 am
    Room 300, Bldg. 555

    Hosted by: Jan Hrbek

  163. Chemistry Colloquium Series

    "SNOLAB and the Search for Neutrinoless Double Beta Decay in Xenon"

    Presented by David Sinclair, Carleton University

    Wednesday, November 5, 2008, 1 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Minfang Yeh

    This talk will describe the new SNOLAB facility for the study of fundamental physics in an ultra-low background environment. SNOLAB is an extension of the facility built for the SNO solar neutrino experiment. The work towards a potential experiment in this facility looking for double beta decay in xenon will then be described. The plan is to look at a gaseous version of the EXO detector incorporating in-situ detection of the daughter barium ion. Some of the technical issues which must be overcome to make such a detector a reality will be presented together with a progress report on some of the solutions.

  164. Chemistry Department Seminar

    "Light and Metal: Surface Plasmon Devices and Circuitry"

    Presented by T.W. Ebbesen, ISIS, University Louis Pasteur and CNRS, Strasbourg, France

    Thursday, October 30, 2008, 11 am
    Room 300, Bldg. 555

    Hosted by: John Miller

    Materials structured on the nanometer scale can lead to improved and sometimes surprising properties. Metals are no exception to this rule. Metal particles for instance display colours which vary with their size. The colour results from the coupling of light with the free electrons of the metal particle to form surface plasmons. With modern nanofabrication techniques it is possible to tailor the structure of metals and thereby to control the properties of surface plasmons opening many new possibilities for photonic devices, molecular sensors and miniature optical circuits. This potential of nanostructured metals will be illustrated by the recent progress in the field [1-3]. 1. Barnes, Dereux and Ebbesen, Nature 424, 824 (2003); 2. Genet and Ebbesen, Nature 445, 39 (2007); 3. Ebbesen, Genet et Bozhevolnyi, Physics Today (mai 2008).

  165. Center for Functional Nanomaterials Seminar

    "Solution Manipulation of Single-walled Carbon Nanotubes and Their Applications in Electrochemistry"

    Presented by Dan Wang, Ohio University

    Monday, October 27, 2008, 10 am
    Bldg. 735 - conf rm A

    Hosted by: Weiqiang Han

    Single-walled carbon nanotubes (SWNTs) exhibit extraordinary mechanical, thermal and electrical properties due to their unique one dimensional all-carbon structure. However, as-produced carbon nanotubes are typically bundled mixture of various species due to strong inter-tube van der Waals interactions and hydrophobic interactions in aqueous environments. Thus, SWNTs have to be first dispersed in organic or aqueous solvents before solution-phase processing, separation, and assembly can become successful. Here we designed a “polysoap” surfactant which not only disperses SWNTs in aqueous solution, but also acts as templates for the binding of metal ions and nanoparticles (NPs) to synthesize SWNT-metal NP assemblies in solution. In many potential applications, it is desirable to control the dispersion or aggregation of SWNTs in solvents with external stimuli. I will report two “smart” SWNT dispersions that respond to temperature and pH changes in poly(N-isopropylacrylamide) (PNIPAAm) and poly-L-lysine (PLL) solutions. I will also introduce biocatalytic electrodes based on transparent and conducting SWNT thin films and glucose oxidase (GOx) catalyzed direct electron transfer via simple immobilization with PLL and Nafion.

  166. Chemistry Colloquium Series

    "The Effects of Particle Size, Coating and Reactivity on Cell Function"

    Presented by Miriam Rafailovich, State University of New York at Stony Brook, Dept. of Materials Science & Engineering

    Tuesday, October 7, 2008, 11:30 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Miomir Vukmirovic

    Nanoscale engineering is one of the most dynamically growing areas in science and industry. As there are no safety regulations yet, concerns about future health problems are mounting. The fundamental question that arises is, whether size alone can be detrimental. In order to investigate this issue, one must study the effects of both inert i.e. noble metal (1) and chemically active (Ti and Zn oxide) nanoparticles (2). Living tissues are composed of a hierarchy of cell structures, where each layer has a unique cell type and function. Here I will focus on the impact of the nanoparticles on the function of various types of primary culture skin cells. Skin tissue is chosen as a model since it is the first barrier to penetration from contact type of exposure. We found that, even at very low concentrations, where no apoptosis was detected, both types of particles were capable of interfering with normal cell functions such as migration, proliferation, and ECM formation. In the case of inert particles, a critical concentration existed below which recovery was possible if the source of particles was removed. Particles which are coated will interact differently with the cell membrane. The effects of adsorbed plasma proteins, as well as synthetic coatings will be discussed (2). 1. Adverse effects of citrate/gold nanoparticles on human dermal fibroblasts Pernodet N, Fang XH, Sun Y, Bakhtina A, Ramakrishnan A, Sokolov J, Ulman A, Rafailovich M. Small 2006 2 (6): 766-773 2. Multicomponent polymer coating to block photocatalytic activity of TiO2 nanoparticles, Wilson A. Lee,Nadine Pernodet, Bingquan Li, Chien H. Lin, Eli Hatchwell and Miriam H. Rafailovich, Chemical Communications (2007) Pages: 4815-4817

  167. Chemistry Department Seminar

    "Overall Water Splitting On Some Oxynitride-Based Photocatalysts"

    Presented by Kazunari Domen, University of Tokyo, Japan

    Thursday, July 31, 2008, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: James Muckerman

    Abstract: Water splitting to form hydrogen and oxygen with solar energy is one of the attractive candidates for clean and sustainable energy production. Some oxynitrides work as visible light responsive photocatalysts for overall water splitting with proper modifications. GaN:ZnO and ZnGeN2:ZnO solid solutions with core-shell type hydrogen evolution sites will be discussed in detail. In addition, two-step photo-excitation systems for overall water splitting under visible light with the wavelengths longer than 600 nm will be introduced.

  168. Chemistry Department Colloquium


    Presented by Hua-Gen Yu, Brookhaven National Laboratory - Chemistry Department

    Monday, July 21, 2008, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: James Muckerman

    Fast chemical reactions play an important role in many environments such as combustion, intermediate clouds and the atmosphere of Earth. They often involve molecular ions and radicals which are not easily investigated experimentally. In this talk we are going to discuss an efficient and accurate ab initio molecular dynamics. (AIMD) method to study both dynamics and kinetics properties of those chemical reactions. In addition, a spherical electron cloud hopping (SECH) model will be first presented for studying product branching ratios of dissociative recombination (DR).

  169. Chemistry Department Seminar

    "Nanostructures and nanomaterials fabricated by electron irradiation techniques and their applications"

    Presented by Sung Oh Cho, Korea Advaned Institute of Science and technology, South Korea

    Friday, July 18, 2008, 1:30 pm
    Room 300, Building 555

    Hosted by: Sergei Lymar

    Various nanostructured materials, such as light-emitting nanoarchitectures, hierarchical porous structures, metal nanoparticles, microporous polymer, sponge-like microporous silica, non-closed packed nanoarrays, and nanotrees were fabricated by simply irradiating an electron beam onto organic and inorganic precursors. Electron irradiation decomposes the precursor materials and changes the molecular structure of the materials. As a result, new materials of the chemical structures that is completely different from the precursors can be created from the precursors. The morphologies and the chemical structures of the final products can be controlled by changing the electron irradiation parameters and the precursor materials. The electron approach is a straightforward approach to synthesize a variety of nanostructured materials because a single electron irradiation process is necessary for the production of the final products. Moreover, the electron irradiation approach is a parallel process and thus the nanostructured materials can be prepared on a large scale by increasing the irradiation area of an electron beam, allowing mass production of the materials. These unique nanostructured materials can be used for diverse applications, such as superhydrophobic and superhydrophilic films, low-dielectric coating, and photonic devices. Moreover, we recently found that some organic and inorganic materials can be transformed into semiconducting materials by electron irradiation. Consequently, the produced materials promise their applications to light-emitting devices, organic solar cells, and photocatalysts.

  170. Chemistry Department Colloquium

    "The Evoluation of Ionic Liquids - From Solvents and Separations to Advanced Materials and Pharmaceuticals: Examples from the Ionic Liquid Cookbook"

    Presented by Professor Robin D. Rogers, University of Alabama, Department of Chemistry

    Monday, July 14, 2008, 1:30 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: James Wishart

    Ionic Liquids (ILs) per se have been known over a century, but they have come under intense worldwide scrutiny only relatively recently due to implications for the use of these compounds as solvents, where the accessible physical property set (e.g., non- or low-volatility, thermal stability, or large liquid ranges) achievable with many ILs are often unique. There is now, however, growing interest in the materials applications of ILs which utilize novel tunable physical and chemical property sets for such applications as energetic materials, lubricants, metal ion complexation, etc. While a tremendous amount of recent research has focused on the physical properties of ILs, and more recently the chemical properties, the toxicity, a biological property has been one of the most highly debated topics in this field. Here we consider then, the third evolution of ILs where biological activity is the primary IL property and look at ILs as active pharmaceutical ingredients (APIs). Taken together, it is clear that ILs offer almost every technological field an opportunity to advance knowledge and performance.

  171. Chemistry Department Colloquium

    "Metal-Loaded Liquid Scintillator for Neutrino Physics"

    Presented by Minfang Yeh, Brookhaven National Laboratory, Chemistry Department

    Wednesday, June 18, 2008, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Richard Hahn

    After the first direct observation of neutrino flavor transformations at the Sudbury Neutrino Observatory, future planned neutrino experiments are focusing on the understanding of the neutrino oscillation mechanism by determining key neutrino parameters, such as the mass differences and mass hierarchy, the mixing angles, and the possibility of CP violation. Organic liquid scintillators (LS) have been the detection medium of choice for neutrinos since the early discovery experiment of Reines and Cowan. For the delayed neutron-capture signal, the advantages of adding a metal element to the LS (to form M-LS) are significant. Chemically, there are challenges to adding inorganic salts of metal, such as directly to the LS. Key aspects of the metal-loaded LS (M-LS) for neutrino detection are (a) long-term chemical stability, (b) high optical transparency, (c) high photon production by the LS, and (d) ultra-low impurity content, mainly of natural radioactive contaminants, such as U, Th, Ra, and Rn. BNL Neutrino & Nuclear Chemistry group holds a long history of neutrino research since Ray Davis’s pioneering Homestake experiment and has developed new chemical techniques of loading metals, such as In, Yb, Gd, Nd, and currently Li and Ca, in organic liquid scintillator that can be used for low-energy solar neutrino, reactor neutrino, or double-beta decay experiments. The chemical-doping technologies and the performance of different organometallic liquid scintillators for different experiments will be discussed.

  172. Chemistry Department Colloquium

    "The sigma-CAM mechanism: The dance of sigma-complexes that achieves metathesis at late transition metals"

    Presented by Professor Robin Perutz, University of York, Dept. of Chemistry, U.K.

    Tuesday, May 27, 2008, 11 am
    Room 300, Chemistry Bldg.555

    Hosted by: Etsuko Fujita

    A sigma-bond, as in H2, can act as a donor to a metal resulting in a dihydrogen complex. This is best known of the class of sigma complexes but others are formed by boranes, silanes and alkanes. In this seminar, I will show how studies of rapid rearrangements have brought about the realization that sigma complexes can provide the key to interconversion of functional groups at a late transition metal without change of oxidation state. We call this the sigma-CAM mechanism and it is quite distinct from the usual mechanisms of metathesis. (see Angew Chem 2007, 46, 2578-2592). I will also describe experiments designed to detect sigma-complexes as reaction intermediates.

  173. Chemistry Department Colloquium

    "Discovery of Novel Hydrogen Storage Materials: An Atomic Scale Computational Approach"

    Presented by Professor Christopher Wolverton, Northwestern University, Dept. of Materials Science & Engineering

    Wednesday, May 14, 2008, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Ping Liu

    Practical hydrogen storage for mobile applications requires materials that exhibit high hydrogen densities, low decomposition temperatures, and fast kinetics for absorption and desorption. Unfortunately, no reversible materials are currently known that possess all of these attributes. Here we present an overview of our recent efforts aimed at developing a first-principles computational approach to the discovery of novel hydrogen storage materials. Such an approach requires several key capabilities to be effective: (i) Accurate prediction of decomposition thermodynamics, (ii) Prediction of crystal structures for unknown hydrides, and (iii) Prediction of preferred decomposition pathways. We present examples that illustrate each of these three capabilities: (i) prediction of hydriding enthalpies and free energies across a wide range of hydride materials, (ii) prediction of low-energy crystal structures for complex hydrides, [such as Ca(AlH4)2 CaAlH5, and Li2NH], and (iii) predicted decomposition pathways for Li4BN3H10 and destabilized systems based on combinations of LiBH4, Ca(BH4)2 and metal hydrides. For the destabilized systems, we propose a set of thermodynamic guidelines to help identify thermodynamically viable reactions. These capabilities have led to the prediction of several novel high-density hydrogen storage materials and reactions.

  174. Chemistry Department Colloquium

    "Structure and Sensitization of Titanium Dioxide Surfaces"

    Presented by Professor Annabella Selloni, Princeton University

    Wednesday, April 16, 2008, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Ping Liu

    This talk will give an overview of recent theoretical work meant at obtaining insights into issues relevant to TiO2-based photocatalysis. Topics to be discussed include the influence of surface structure on the adsorption of different species, and surface sensitization via absorbed chromophores as used in dye sensitized solar cells.

  175. Atmospheric Sciences Division Seminar

    "Phase Transfer Properties, Ozonolysis and Photochemistry of Organic Films of Atmospheric Relevance"

    Presented by Markus Ammann, Paul Scherrer Institute, Switzerland

    Friday, April 11, 2008, 11 am
    Building 815 Conference Room

    Hosted by: Art Sedlacek

    Atmospheric aerosol particles host a very complex mixture of organic and inorganic components. A significant fraction of organics present in aerosol particles are surface active, such as linear alkanoic and alkenoic acids or aromatics with hydrophilic substituents. Using reasonably well defined proxy systems, we have started to look at three different aspects of organic coatings: first, they may establish a barrier towards the transfer of trace gases from the gas phase into the aerosol phase. We have used the fast uptake of nitric acid to deliquesced NaCl particles to probe the effect of long chain C9 to C18 saturated and unsaturated fatty acids, indicating that the monolayer forming properties of these fatty acids determines the degree of reduction of phase transfer of nitric acid to the aqueous particles. Second, the chemical environment in a coating is substantially different from that in either the pure organic or the aqueous bulk phases. This is demonstrated with ozonolysis studies of oleic acid monolayers on deliquesced NaCl particles, which shows substantial formation of H2O2, exceeding that from bulk oleic acid ozonolysis or that known from alkene oxidation in the gas phase. Third, a number of species in organic coatings are absorbing light in the visible and UVA wavelength range. We have specifically investigated photosensitized redox processes that lead, among other things, to light induced reaction of organics with nitrogen dioxide and ozone, the former becoming a substantial source of nitrous acid in the lowermost troposphere.

  176. Chemistry Department Colloquium

    "The charge-lattice coupling at a photocatalytic interface"

    Presented by Professor Hrvoje Petek, University of Pittsburgh, Dept, of Physics & Astronomy

    Thursday, April 3, 2008, 12 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Nick Camillone

    The coupling of charge and nuclear degrees of freedom is a prerequisite for inducing photocatalytic processes at semiconductor-molecule interfaces. We explore the correlations between the structural and electronic properties of rutile TiO2(110) surface by low-temperature STM, ultrafast time-resolved photoemission spectroscopy, and first-principles theory. LT-STM measurements of reduced TiO2(110) surfaces describe the structure and excess electron distributions at O atom vacancy defect sites. DFT calculations indicate strong correlation between the lattice relaxation and the electronic structure. Time-resolved photoemission studies of H2O and CH3OH covered surfaces show the dynamical response of the interface to photoinduced charge transfer into the molecular overlayer (1-3). In particular, the dynamics of reverse charge transfer from the CH3OH overlayer show strong evidence of proton-coupled electron transfer.

  177. Medical Department Seminar

    "Short Talk on PET Chemistry and Translational Research (2d seating for visiting SUNY at Stony Brook students)"

    Presented by Louis Pena, Medical Department, BNL

    Friday, March 28, 2008, 10 am
    Small Conf. Rm. A/B (490)

    Hosted by: Louis Pena

  178. Medical Department Seminar

    "Short Talk on PET Chemistry and Translational Research (1st seating for visiting Yeshiva Univ. students)"

    Presented by Joanna Fowler, Medical Dept., BNL, USA

    Friday, March 28, 2008, 9 am
    Bldg. 555

    Hosted by: Joanna Fowler

  179. Chemistry Department Colloquium

    "Some Ways in which Surface Oxides Facilitate or Hinder Reactions"

    Presented by Professor Talat Shahnaz-Rahman, University of Central Florida, Dept. of Physics

    Wednesday, March 26, 2008, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: James Muckerman

    It is conventional knowledge that metal surfaces are more reactive than those of their oxides. However, recent experimental results indicate that metal oxide surfaces may be quite reactive, leading to questions about the role of surface atoms and their vacancies in the reactions. Motivated by experimental results which show that the rate of CO oxidation on Cu2O surface is much higher than that on Cu and CuO surfaces [1], and that while RuO2(110) facilitates CO and NH3 oxidation, it does not do the same for NO [2], I will present results from first principles electronic structure calculations of the energetics of adsorption, diffusion, dissociation and oxidation of relevant molecules on corresponding oxide surfaces. Conclusions will be drawn about the characteristics of the surface electronic structure and local environment that may hinder or facilitate a particular reaction. Since reactions may leave oxygen vacancies in the surface, I will also address the question of healing of the surface. I will comment on the relevance of our result to recent observation of the reactivity of Cu2O nanoparticles[3] and of the oxide substrate in enhancing the reactivity of Au films [4]. In commenting on the relevance of our result to experimental observations I will present results also from kinetic Monte Carlo simulations with support from analysis of the local densities of electronic states and valence charge densities of the systems. . 1. T.-J. Huang and D.-H. Tsai, Catal. Lett. 87, 173 (2003). 2. S. Hong, TSR, K. Jacobi, G. Ertl, J.Phys. Chem. 3. B. White, M. Yin, A. Hall, D. Le, S. Stolbov, TSR, N. Turro, and S. O'Brien, Nano Letters 6, 2095 (2006). 4. M. S. Chen and D. W. Goodman, Surf. Sci. (2006). * Work supported in part by DOE under Grant No. DE-FG02-07ER15842

  180. Chemistry Department Seminar

    "Understanding gas-electrode interactions in solid oxide fuel cells using quantum chemical calculations"

    Presented by YongMan Choi, Georgia Institute of Technology

    Monday, March 24, 2008, 1:30 pm
    Room 300, Bldg.

    Hosted by: Ping Liu

    Solid oxide fuel cells (SOFCs) have become more attractive owing to their highly efficient power generation, versatile applications, fuel flexibility, and low emissions. One of the most crucial technical challenges in SOFCs is to design novel electrode materials that tolerate low concentrations of sulfur-containing species such as H2S and operate efficiently below 700 oC. Most of mechanistic details cannot be directly measured experimentally due to the complexity of gas-surface interactions. Therefore, it is imperative to understand the detailed mechanisms for H2S decomposition and oxygen reduction on the anode and cathode surfaces, respectively, at the molecular level in order to achieve the goal. In this presentation, some recent progress in elucidation of the reaction mechanisms by means of quantum chemical calculations will be highlighted.

  181. Chemistry Department Colloquium

    "Nanoparticles and Nanowires: Preparation, Morphology and Synchrotron Spectroscopy"

    Presented by Dr. Tsun-Kong Sham, University of Western Ontario, Canada

    Thursday, February 28, 2008, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Jan Hrbek

    Strategies in the fabrication of nanomaterials such as Au nanoparticles, and a number of semiconductor nanowires or nanoribbons of Si, SiO2, Ge, GeO2, ZnO, ZnS, CdSe, SnO2 etc. conducted in our laboratory will be briefly described. The morphology of these systems examined by electron microscopy will be presented. The electronic structure of these systems has been investigated with synchrotron based spectroscopy to reveal the interplay of surface and size effects in Au nanoparticles and the morphology dependent luminescence properties of ZnS and ZnO nano structures. The technique sometimes known as X-ray Excited Optical Luminescence (XEOL) in both the energy and time domain (Time-resolved XEOL) will be described in some details and its application illustrated with the investigation of a light emitting nanowire CdSe-Si heterostructure.

  182. Chemistry Department Seminar

    "Thermal Stability, Electronic, and Catalytic Properties of Supported Metal Clusters: Size, Interparticle Interactions, Oxidation and Support Effects"

    Presented by Professor Beatriz Roldan-Cuenya, University of Central Florida

    Thursday, January 31, 2008, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Jose Rodriguez

    The next generation of nanocatalysts requires detailed knowledge of the correlation between their structure (geometrical and electronic) and their activity. Size- and shape-selected Au and AuFe nanoclusters with well defined intercluster distances were synthesized by diblock copolymer encapsulation. Significant changes in the electronic local density of states (LDOS) of TiC-supported Au clusters, in particular, the onset of non-metallic behavior, were observed by scanning tunneling spectroscopy with decreasing cluster size. In addition, evidence for substrate-induced modifications in the LDOS of interfacial gold atoms was found [1]. When the Au clusters are deposited on reduced TiO2, the LDOS distribution within the clusters is inhomogeneous and appears to be enhanced at low-coordinated Au atoms. The possibility of electron transfer from the reduced TiO2 support to the nanoclusters will be discussed. The enhancement of electron density inside and around metal clusters is of scientific importance, since it has been predicted to facilitate the adsorption and dissociation of reactants with low activation energies. Our temperature programmed desorption measurements (TPD) indicate a size-dependency in the catalytic activity of Au/TiC for low temperature CO oxidation [2]. Furthermore, interparticle interactions were found to affect the activity and life-time of our catalysts [3]. The thermal and chemical stability of oxidized gold species formed upon cluster exposure to atomic oxygen was investigated using a combination of temperature-, time- and CO dosing-dependent X-ray photoelectron spectroscopy (XPS) and TPD [4]. Our work demonstrates that low temperature exposure to atomic oxygen leads to the formation of surface, as well as sub-surface gold oxide on Au nanoparticles. Interestingly, the presence of a reducible TiO2 substrate leads to a lower gold oxide stability compared to that on SiO2, possibly due to a TiO2 oxygen vacancy-mediated decomposition process. Finall

  183. Center for Functional Nanomaterials Seminar

    "Nanocrystals Prepared by Modern Materials Chemistry Methods"

    Presented by Stephen O'Brien, Columbia University

    Wednesday, January 30, 2008, 1:45 pm
    CFN - 2nd Floor Seminar Room

    Hosted by: Emilio Mendez

    Center for Functional Nanomaterials Seminar Wednesday, January 30, 2008, 1:45 pm CFN Building 735 – Second Floor Seminar Room NANOCRYSTALS PREPARED BY MODERN MATERIALS CHEMISTRY METHODS STEPHEN O’BRIEN, DEPT. APPLIED PHYSICS AND MATERIALS RESEARCH SCIENCE AND ENGINEERING CENTER, COLUMBIA UNIVERSITY, NEW YORK NY 10027, USA Nanocrystals prepared by modern materials chemistry methods are discrete units with a crystalline inorganic core and an organic ligand coating for a shell. They are best thought of as an inorganic-organic hybrid when considering their applications, functionality and properties. Here I describe two examples of their use as building blocks. (i) Monodisperse Magnetic Nanoparticles for Specific Antibody Targeted MRI Contrast Imaging. Non-invasive imaging of specific proteins or cells in the body has the potential to improve the diagnosis and treatment of numerous diseases. We report here the development of a long-lived immunotargeted iron oxide nanoparticle contrast agent composed of monodispersed, monocrystalline γ-Fe2O3 iron oxide nanoparticles coated with a monolayer of phospholipids and conjugated to modified IgG antibodies. Proof of specificity is demonstrated using MHC Class II antibodies. MR images were taken of Lewis rats injected with 4 mg/kg unconjugated iron oxide nanoparticles using T1 weighted, T2 weighted Fast Spin Echo and T2* weighted scan sequences. (ii) Nanocrystal superlattices of II-VI semiconductors. Nanocrystals can be used as building blocks to form simple ordered arrays, called superlattices, which resemble the close-packed structures of atoms in crystals or hard spheres. The procedure can be described as a co-crystallization of nanocrystal dispersions following appropriate choice of solvents, substrates and conditions for self-assembly. The superlattices that result exhibit remarkable structural and compositional diversity, representing a variety of close packed structures reminiscent of binary alloy phase

  184. Chemistry Department Colloquium

    "Tripping the Light Fantastic: Ultrafast Studies of Chromoproteins"

    Presented by Professor Peter Tonge, Stony Brook University, Dept. of Chemistry

    Wednesday, January 30, 2008, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Gregory Hall

    A detailed microscopic understanding of how excited state dynamics both control and are controlled by the molecular environment is critical for the design of light-driven nanoscale molecular devices. We are using methods such as picosecond time resolved infrared spectroscopy (TRIR) to analyze the ground and excited state structure of the chromophore in two chromoproteins: the fluorescent protein, GFP, and the photoreceptor AppA. In each case we are interested in understanding how the protein matrix controls and modulates the response of the chromophore to light absorption.

  185. Chemistry Department Seminar

    "Controlling Molecular Fragmentation with Shaped Laser Pulses"

    Presented by Thomas Weinacht, Dept. of Physics, Stony Brook University

    Tuesday, December 4, 2007, 11 am
    Room 300, Bldg. 555

    Hosted by: Trevor Sears

  186. Director's Office Seminar

    "Advances in Macromolecular Materials Chemistry at the Electronics/Photonics Interface"

    Presented by Elsa Reichmanis, Bell Laboratories, Alcatel-Lucent

    Friday, October 26, 2007, 2 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Doon Gibbs

  187. Atmospheric Sciences Division Seminar

    "Atmospheric Chemistry of Environmental Interfaces"

    Presented by V. Faye McNeill, Columbia University

    Monday, August 20, 2007, 1:30 pm
    Building 815E, Conference Room

    Hosted by: Jian Wang

    - Chemical and physical processes occurring at environmental interfaces can have a profound impact on the chemical balance of the atmosphere. I will discuss two examples from my research: (1) Heterogeneous ice chemistry relevant to polar stratospheric ozone depletion: We have shown that trace amounts of HCl induce formation of a disordered region, or quasi-liquid layer at the ice surface at stratospheric temperatures. We also showed that surface disordering enhances the chlorine activation reaction of HCl with chlorine nitrate (ClONO2), and also enhances acetic acid (CH3COOH) adsorption. These results impact our understanding of the chemistry and physics of ice particles in the atmosphere, explaining the catalytic role that ice particles play in chlorine activation. (2) Surface active organic films on aqueous aerosols: We have shown that submonolayer films of expanded-state surfactants can significantly suppress the reactive uptake of N2O5 by submicron aqueous aerosols. We used aerosol flow tube reactors with chemical ionization mass spectrometry detection of the gas and particle phases in order to assess the lifetimes of such films when subject to oxidation in the atmosphere. We conclude that for the aerosol compositions studied, oxidation occurs near the gas-aerosol interface and that the 1 e-fold lifetime of unsaturated organics at the aerosol surface is ~10 minutes due to O3 oxidation under atmospheric conditions. Results will also be shown for the OH oxidation of pure and mixed organic-inorganic aerosols containing palmitic acid. 1. McNeill,V. F., Loerting, T., Geiger, F. M., Trout, B. L., and Molina, M. J. Hydrogen chloride-induced surface disordering on ice. Proc. Natl. Acad. Sci. USA 103, 9422-9427 (2006). 2. McNeill,V. F., Patterson, J., Wolfe, G. M., and Thornton, J. A. The effect of varying levels of surfactant on the reactive uptake of N2O5 to aqueous aerosol. Atmos. Chem. Phys. 6, 1635-1644 (2006). 3. McNeill, V. F., Wolfe, G. M., and Thor

  188. Medical Department Seminar

    "Future Trends in Nuclear and Radiochemistry"

    Presented by George R. Choppin, R.O. Lawton Dist. Prof. of Chem, Dept of Chemistry & Biochemistry, Florida State University, Tallahassee, FL

    Wednesday, July 18, 2007, 9 am
    Small Conf. Room, Bldg. 490

    Hosted by: A. J. Francis

    Although nuclear and radiochemistry can be considered mature branches of chemistry one hundred years after the discovery of radioactivity, challenges abound for chemists in many areas in nuclear science. Global interest in nuclear and radiochemistry encompasses a wide range of difficult tasks, including the remediation of contaminated nuclear facilities, limiting nuclear proliferation, providing clean and efficient power for the developed and developing world, the diagnosis and treatment of disease, and the advancement of biological, physical and earth sciences. With the increased understanding of the “Greenhouse Gas Problems” the need for abundant, clean nuclear energy is becoming recognized as more of a necessity internationally. Education in nuclear and radiochemistry is vital to the success of these endeavors. The present status of nuclear education internationally is reviewed and the necessary future developments are discussed.

  189. Condensed-Matter Physics & Materials Science Seminar

    "Using Stereochemistry to Control Structure and Rheology: Teaching Old Biomaterials New Tricks"

    Presented by Surita Bhatia, University of Massachusetts Amherst

    Monday, May 7, 2007, 10 am
    Small Seminar Room, Bldg. 510

    Hosted by: James Misewich

    Soft biomaterials derived from amphiphilic polymers have received considerable attention in the last decade. The ability to tune the modulus of implantable materials to match that of native tissue is crucial for scaffolding applications; unfortunately, a significant limitation of current polymeric biomaterials is a lack of mechanical robustness and a low elastic modulus. I will discuss a collaborative effort to address these issues using hydrogels of poly(lactic acid)-poly(ethylene oxide)-poly(lactic acid) (PLA-PEO-PLA) triblock copolymers. These materials form associative network gels with the PLA domains serving as network junctions. Our work distinguishes itself from previous studies through controlled stereochemistry of the PLA blocks and crystallinity of the junction points. We can create nanoscale crystalline junctions through use of copolymers in which the PLA block is poly(L-lactic acid) (PLLA), or amorphous junctions through copolymers in which the PLA blocks contain a racemic mixture of D-lactic acid and L-lactic acid (PRLA). The crystalline junctions in the PLLA-based gels cause a significant increase in the elastic modulus over the PRLA gels, allowing us to create gels with elastic moduli that are an order of magnitude higher than previously reported with PLA-based associative gels. The modulus is also very sensitive to PLA block length and can be easily tuned to match the moduli of native tissue such as cartilage. We have also shown that crystalline PLA domains lead to a microporous gel structure, which is useful for tissue engineering applications, and that PLA block length and stereochemistry can be used to control the drug release characteristics of our systems. Finally, we have incorporated inorganic nanoparticles into these gels and have demonstrated that this enhances the elastic modulus and improves viability of encapsulated chondrocytes. Biosketch: Surita Bhatia’s research interests lie in the area of complex fluids, polymeric

  190. Chemistry Department Seminar

    "High resolution REMPI spectroscopy of biological molecules and their water clusters: Conformeric structures and fragmentation"

    Presented by Prof. Hans Juergen Neusser, TU Munchen - Dept. of Chemistry, Germany

    Wednesday, February 14, 2007, 1:30 pm
    Room 300, Chemistry Bldg. 555

    Hosted by: Dr. Michael White

  191. Chemistry Department Seminar

    "Development of Bioinspired Electron-Transfer Systems for Energy Conversion"

    Presented by Professor Shunichi Fukuzumi, Osaka University, Japan

    Friday, February 9, 2007, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dr. Etsuko Fujita

    The rapid consumption of fossil fuel has caused unacceptable environmental problems such as green house effects, which would lead to disastrous climatic consequences. Thus, renewable and clean energy resources are definitely required in order to solve global energy and environmental issues: Since nature harnesses solar energy for its production by photosynthesis, why not imitate nature to create artificial photocatalytic electron-transfer systems that exploit the basic chemistry of photosynthesis in order to produce hydrogen or other fuels? The specific objective of this lecture is therefore to describe recent development of bioinspired electron-transfer systems including artificial photosynthesis and respiration together with their applications. First, multi-step electron-transfer systems composed of electron donor-acceptor ensembles have been developed, mimicking functions of the photosynthetic reaction center.2'3 However, a significant amount of energy is lost during the multi-step electron-transfer processes. Then, as an alternative to conventional charge-separation functional molecular models based on multi-step long-range electron transfer within redox cascades, simple donor-acceptor dyads have been developed to attain a long-lived and high energy charge-separated state without significant loss of excitation energy.4-7 Such simple molecular dyads, capable of fast charge separation but extremely slow charge recombination, have significant advantages with regard to synthetic feasibility, providing a variety of applications including construction of organic solar cells and development of efficient photocatalytic systems for the, solar energy conversion.8-11 On the other hand, the four-electron reduction of 02 is not only of great biological interest, but also of technological significance such as fuel cells. Thus, recent development of efficient electron-transfer catalytic systems for four-electron reduction of 02 is also presented and the catalytic mechan

  192. Chemistry Department Seminar

    "Light-Induced Transient Bonding: A Way To Control Charge Separation?"

    Presented by Julia A. Weinstein, University of Sheffield, United Kingdom

    Monday, January 29, 2007, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: David Grills

    Photoinduced electron transfer plays a fundamental role in a variety of light-energy conversion processes, from photosynthesis to photocatalysis, with a charge-separated excited state being a key transient in many of those. Such states are formed as a result of photo-induced electron transfer in an essential Donor-Spacer-Acceptor component. In artificial systems, the charge-separated [D+-sp-Ai* state is often too short-lived due to facile back electron transfer. The fundamental challenge is how to block back electron transfer until the excited state becomes engaged into a desired chemical event. e + — * To explore light-induced formation of a transient three-electron S∴ S-bond on a metal template as a way to stabilize charge separation. The formation of a new bond in the excited state, which is not present in the ground state, would create an activation barrier for back electron transfer. METHODS: A combination of pico-to-milli-second transient absorption, emission, and time-resolved resonance Raman (TR3) techniques is utilized in order to test and develop the “S∴ S” hypothesis. (Spectro)electrochemistry (UV-NIR, EPR) and pulse radiolysis methods are also used to obtain information on spectral signatures of the radical cations and anions supplementary to the excited state structure. Theoretical calculations into the structure of excited states are performed in collaborations. SYSTEMS: The current model systems are Pt(II) diimine-dithiolates, show a 100-fold variation in the excited state lifetime and reactivity as a function of electron donor/acceptor properties of the “RS”-ligand. Such “core” Pt(II) complexes are presently being incorporated into multi-component assemblies for long-distance electron transfer, in which an interplay between electron and energy transfer on the picosecond time scale offers great promise for a “switchable” excited state behaviour.

  193. Chemistry Department Seminar

    "Spin States, Unsaturation, and Pi-Donation: Impact on Reactivity?"

    Presented by Professor Kenneth Caulton, Indiana University

    Wednesday, January 17, 2007, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: David Grills

    It will be argued that the amide ligand (tBu2PCH2SiMe2)2N-1, “PNP” creates a sterically protected (from tBu) and electron rich (from amide N donation) metal center. For Ru(II), the compound (PNP)RuCl is unusual in being “doubly unsaturated,” 4 coordinate and planar, and this leads to facile binding of PhCN, C2H4, and N2, but remarkably “deeper” reactions with H2, with terminal alkynes, and with Me3SiN3. The analogous osmium chemistry shows dramatic differences, leading into the chemistry of radical species, and rhodium shows formation of an adduct with an arene C-H bond coordinating to the metal, as well as C-H bond cleavage ability. Understanding all of this reaction chemistry is enhanced by concurrent DFT calculations. Generalization of the above reactivity principles is possible by studies with lighter transition elements Fe, Co and Ni, which, in turn, leads to results relevant to the concept of a chemical reaction being “spin forbidden.”

  194. Chemistry Department Seminar

    "Pi-Conjugated Organometallic Oligomers and Polymers: Triplet Exciton Structure, Dynamics and Materials Applications"

    Presented by Dr. Kirk Schanze, University of Florida

    Friday, January 5, 2007, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dr. John Miller

    A series of Platinum-Acetylide oligomers and polymers have been investigated with the objective of understanding the structure and dynamics of triplet excitons in pi-conjugated electronic systems. Photophysical investigations provide clear evidence that the triplet exciton is localized in conjugated systems. Moreover, the dynamics of intrachain diffusion can studied at temperatures below 200 K. Platinum-acetylide materials also find use in applications ranging from organic photovoltaic cells to optical pulse limiting.

  195. Chemistry Department Seminar

    "Rational Molecular Design for Photoelectrochemical Devices"

    Presented by Professor Hiroshi Imahori, Department of Molecular Engineering, Kyoto University, Japan

    Friday, December 1, 2006, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Etsuko Fujita

    Extensive efforts have been made in recent years to explore the photovoltaic and photoelectrochemical properties of electrodes modified with various donor and acceptor components toward the realization of highly efficient organic solar cells. In this talk we present rational molecular design for Photoelectrochemical Devices. First, we examined substituent effect of meso-tetraphenylporphyrin (TPP) on the molecular packing with C60 and its photoelectrochemical properties of SnO2 electrodes modified with the composite clusters of TPP and C60. In the molecular design of TPP we consider the following criteria. i) Electron-donating substituents (i.e., methoxy group) are introduced into meta-positions of the meso-phenyl groups at the porphyrin ring to strengthen the supramolecular complexation between TPP and C60 due to the _i-_i interaction. ii) Taking into account the three-dimensional molecular packing of TPP and C60 in the TPP-C60 composite film, it is suitable to adopt symmetrical substitution of the methoxy groups on the meso-phenyl groups against the porphyrin plane. iii) The methoxy groups between the nearest porphyrins in the TPP-C60 composite films are expected to interact each other due to the hydrogen bonding, yielding porphyrin arrays in the composite films. On the basis of the molecular design, we prepared novel supramolecular photoelectrochemical device where the unique molecular arrangement of the porphyrin with the simple, specific substituent (i.e., meta-methoxy groups) and fullerene on SnO2 electrodes results in the largest IPCE value (~60%) among this type of photoelectrochemical devices. In bulk heterojunction solar cells many researchers have suggested the importance of nanostructured electron and hole transporting pathways which have never been confirmed experimentally. Our experimental results are the first demonstration for the hypothesis. Next, we examined steric effects of dyes and

  196. Chemistry Department Seminar

    "Structure of Surfaces and Nanoclusters Characterized by In-Situ Imaging and Spectroscopy Techniques"

    Presented by Dr. Miguel Salmeron, Lawrence Berkeley National Laboratory

    Thursday, November 2, 2006, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Jose Rodriguez

  197. Chemistry Department Seminar

    "Physicochemical Properties in Functional Genomics; or What Do Polyprotic Acid Equilibria Have To Do with Protein Function Annotation?"

    Presented by Mary Jo Ondrechen, Northeastern University

    Friday, October 13, 2006, 10:30 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: John Miller

    Some simple concepts from physical chemistry form the basis for a computational methodology with valuable predictive capabilities for proteomics and genomics. Our method, called THEMATICS (for Theoretical Microscopic Titration Curves), enables the identification of local interaction sites in protein structures and opens the door to the design of specific ligands for protein structures in advance of biochemical characterization. The ionizable residues in catalytic sites and recognition sites in proteins tend to have theoretical titration curves that deviate significantly from standard Henderson-Hasselbalch (H-H) behavior. It is argued that such non-H-H titration behavior enables both local protonation states to be populated over a wide pH range and that this facilitates catalysis and reversible recognition. THEMATICS uses a Poisson-Boltzmann calculation to obtain the approximate electrical potential function from the 3D structure of a protein, then computes the titration curves (mean charge as a function of pH) for all of the ionizable residues in the structure, then identifies those residues that deviate most from typical H-H form. Clusters of two or more such deviant residues in physical proximity are reliable predictors of catalytic and binding sites in proteins. With optimized statistical criteria, our method predicts sites correctly for 93% of the 170 enzymes in the Catalytic Site Atlas (CSA) ( with a low average filtration ratio of just 3%. Our optimized statistical selection returns an average sensitivity to CSA-annotated catalytic residues of 50% for the CSA proteins; this sensitivity increases to 76% using Support Vector Machines (SVMs). For the electrostatic method with either statistical or SVM selection, average precision rates on a representative sample set of enzymes are two to three times higher than for any other accessible method, with significantly better filtration ratios. Some examples illustrate th

  198. Chemistry Department Seminar

    "Cavity Ringdown Spectroscopy of Several Transient Species"

    Presented by Dr. Alexey Teslja, Columbia University

    Wednesday, September 6, 2006, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Gregory Hall

  199. Chemistry Department Seminar

    "Two-Photon Photoemission Spectroscopy of Wet Electron State and Femtosecond Electron Dynamics on TiO2 Surfaces"

    Presented by Dr. Bin Li, University of Pittsburgh

    Wednesday, September 6, 2006, 9:30 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Dr. John Miller

  200. Chemistry Department Seminar

    "Preparation and Application of Complex Nanostructures"

    Presented by Jun Liu, Pacific Northwest National Laboratory

    Monday, August 28, 2006, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Alex Harris

  201. Chemistry Department Seminar

    "Synthesis, Characterization and Magnetic Properties of Colloidal Nanoparticles"

    Presented by Daniela Zanchet, Brazilian Synchrotron Light Laboratory, Brazil

    Friday, July 28, 2006, 10 am
    Room 300

    Hosted by: Jose Rodriguez

    Colloidal magnetic nanoparticles have attracted much interest in the last few years owing to their fundamental interest and technological applications. The correlation of parameters such as morphology and crystalline structure of the particles with the resulting magnetic properties has been thoroughly investigated in several nanostructure systems, but many open questions remain to be answered. In particular, the intrinsic complexity of nanostructured materials makes a reliable correlation between experimental data and proposed theories difficult. In this aspect, colloidal nanoparticles are particularly interesting due to the possibility of varying different characteristics, such as size and structure, in a more independent and controllable way. In this talk, recent results about the synthesis and characterization of colloidal magnetic nanoparticles such as nickel, iron oxide and cobalt will be presented, and correlated with their magnetic properties.

  202. Chemistry Department Seminar

    "Molecules in Superfluid Helium: from quiescence to turbulence"

    Presented by Professor Curt Wittig, University of Southern California

    Thursday, July 27, 2006, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Gregory Hall

  203. Chemistry Department Seminar

    "Photoinduced Electron Transfer Reactions Of Pt(II) Terpyridyl Complexes"

    Presented by Russell Schmehl, Tulane University, New Orleans, LA

    Wednesday, July 26, 2006, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: David Grills

    In a recent publication, Tung and Wu demonstrated that a group of Pt(II) terpyridyl acetylide complexes yield hydrogen upon photolysis in the presence of dihydropyridines. In addition, others have demonstrated that this class of Pt(II) complexes have excited state behavior that is strongly dependent on terpyridyl substitution and the nature of the fourth ligand. The mechanism of hydrogen production was postulated to involve H atom abstraction from the dihydropyridine by the Pt(II) complex excited state. Our efforts in this area have been to use time resolved absorption and emission spectroscopy to investigate the nature of the excited state of a group of Pt(II) complexes and to explore formation and decay of photoproducts formed in the presence of reductive quenchers. Excited state behavior of four complexes was examined in detail : [(DMAtpy)Pt(II)Cl]+, [(mpt)PtCCPhCl]+, [(mpt)PtCCPhOMe]+ and [(mpt)PtCCPhMe]+ (DMAtpy = 4’-dimethy lamino-2,2’6’,2”-terpyridine; mpt = 4’-(p- methylphenyl)2,2’,6’,2”-terpyridine). Excited state lifetimes, emission maxima and emission quantum yields were strongly dependent on both the terpyridyl substituent and the phenylacetylide substituent. The photoredox reactions of [(DMAtpy)PtCl]+ and [(mpt)PtCCPhCl]+ with a variety of reductive electron transfer quenchers was also examined. With quenchers such as N-methylphenothiazine and triethylamine, excited state quenching rate constants were in excess of 109 M-1s-1 and laser flash photolysis indicated that single electron transfer products were formed. When dihydropyridines, potential H atom donors, were used as quenchers, transient absorption spectra provided evidence that the species formed were the result of electron transfer quenching of the excited state of the Pt complex. The results suggest that formation of the Pt hydrido intermediate in H2 production with dihydropyridine quenchers involves protonation of the one electron reduced species formed in the excited state reaction.2

  204. Chemistry Department Seminar

    "Radiochemical Solar Neutrino Experiments"

    Presented by Dr. Vladimir Gavrin, Institute for Nuclear Research of the Russian Academy of Sciences, Troitsk, Russia

    Friday, June 23, 2006, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Minfang Yeh

    Dr. Vladimir Gavrin has been Director for many years at SAGE, the Soviet-American Gallium (Solar Neutrino) Experiment that is sited in the Baksan (underground) Neutrino Observatory in the Caucasus region of Russia. Both SAGE and GALLEX experiment were designed to use gallium-containing targets to detect the lowest energy neutrinos produced in the sun, in the first step of the pp nuclear-fusion process. Dr. Gavrin will present recent results from SAGE, including neutrino calibration data obtained with a very intense radioactive source of 37Ar. During his talk, he will also include personal reminiscences of his interactions over the years with BNL's Ray Davis and with John Bahcall. Anyone wanting to talk with Dr. Gavrin on June 23 should set up an appointment by contacting the Chemistry Department Office, ext 4301, or Richard Hahn or Minfang Yeh.

  205. Chemistry Department Seminar

    "Localized Nanorod Formation and Crystal Formation in CuTCNQ Systems"

    Presented by Alan M. Bond, Monash University, School of Chemistry, Clayton, Victoria, Australia

    Friday, June 9, 2006, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Steve Feldberg

    CuTCNQ Studies Use of Electrochemical Scanning Probe Studies to characterize the following aspects of semi-conducting CuTCNQ chemistry will be described. (I) The two known phases of CuTCNQ can be probed by SECM in the feedback mode by exploiting the large differences in their conductivity. (II) Films of pure phase II material or mixtures of the CuTCNQ phases can be mapped using feedback mode SECM. However, that the packing density of the individual CuTCNQ crystals in a film structure influences the SECM feedback response. (III) The SECM method enables the surface of single crystals of TCNQ to be modified in a controlled manner to produce highly dense and micrometer sized regions of semiconducting phase I CuTCNQ nanorod crystals by a nucleation and growth mechanism. This method involves the localized reduction of solid TCNQ to TCNQ- by aqueous phase reductant generated at a SECM ultramicroelectrode tip by reduction of , coupled with the incorporation and reduction of ions also present in the aqueous electrolyte. Ionic Liquid Studies Traditionally, voltammetric studies are undertaken on redox active materials dissolved in water, or an organic solvent, in order to understand the thermodynamic and kinetics associated with the electron transfer process, chemical reactions coupled to the electron transfer process and interactions with the electrode surface and solvent. However, many new media are now available for electrochemical investigations. An account of the electrochemistry of cis and trans isomers of Mn(CO)2(CN)(2-Ph2PCH2PPh2)(P(OPh)3) will be given in order to compare voltammetric data obtained in dissolved and solid state formats and illustrate: the use of ionic liquids in electrochemistry; the use of small volume isomer liquid techniques; the use of ionic liquid-aqueous interface in electrochemistry; and the influence of the medium on electron transfer and first order cis+ trans+ chemical isomerization processes.

  206. Chemistry Department Seminar

    "Metal Complexes and Fossil Fuel Upgrading"

    Presented by Roberto Sanchez-Delgado, City University of NY

    Tuesday, May 23, 2006, 11 am
    Room 300, Building 555

    Hosted by: Jose Rodriguez

    Despite the great efforts devoted to the development of alternative energy sources, fossil fuels will probably continue to dominate the scene, particularly for transportation purposes. The refining industry relies mainly on conventional solid catalysts and heterogeneous reactions for the manufacture of gasoline and diesel; however, current and future environmental regulations impose stringent specifications on the quality and the chemical composition of such fuels, which cannot be routinely achieved by current technologies. Therefore, novel catalytic approaches are needed in order to produce gasoline and diesel with the required purity. Transition metal complexes and homogeneous catalytic processes have become common tools in the chemical industry, particularly in fine chemicals and pharmaceuticals, but their potential in relation to fuel manufacture has been largely neglected. In this talk we will describe some attempts to make use of organometallic chemistry and homogeneous or liquid biphasic catalysis to understand or to promote some reactions related to fuel upgrading issues: . • The first example discusses the structures, bonding and reactions of Rh, Ir, and Ru complexes of thiophenes, benzothiophenes and dibenzothiophenes; this chemistry is analyzed in the context of modeling key species and reactions implicated in the industrially important hydrodesulfurization (HDS) process, while drawing mechanistic parallels between organometallic and surface chemistry. Also, the development of some water-soluble catalysts for the aqueous biphasic hydrogenation of benzothiophene, as a possible pretreatment to enhance HDS of refinery cuts, will be described. . . • The second topic deals with the design of new homogeneous and aqueous or ionic liquid biphasic alkene hydroformylation catalysts derived from Rh and Ru phosphine complexes, as a possible means of upgrading gasoline by the in situ carbonylation of undesirable olefins in naphtha to produce environmentally ac

  207. Joint Condensed Matter Physics & Materials Science/CFN Seminar

    "Chemistry at Surfaces: From Self-Assembled Monolayers to Ceramic Thin Films"

    Presented by Chaim Sukenik, Bar Illan University, Israel

    Monday, April 17, 2006, 1:30 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Benjamin Ocko

    Self-Assembled Monolayer (SAM) films can provide surface modification that is both uniform and stable. The direct deposition of functionalized self-assembled monolayers is a simple route to surfaces with customized chemical and physical properties. In situ chemical transformations within an already established monolayer provide a versatile and effective way to install functionality that would otherwise be incompatible with the monolayer-anchoring functionality with which it must coexist prior to SAM formation. SAM modification can also fine-tune monolayer reactivity and provide useful approaches to patterned surfaces which can then be used as templates for further, site specific, surface elaboration. The effective implementation of in situ monolayer chemistry requires reactions that do not compromise monolayer integrity as well as an awareness of the constraints imposed by the organization of the monolayer environment. This presentation will describe a number of examples where functional group chemistry within a self-assembled monolayer film is affected by the constraints of monolayer packing and organization. Examples from carboxylic acid chemistry will be described, along with studies of the influence of the monolayer on both electrophilic and nucleophilic processes. Unexpected behavior in both the yield and selectivity of interfacial chemical processes will be described along with an attempt to understand the extent to which monolayer organization can perturb interfacial properties and processes. Functionalized monolayer surfaces will also be shown to provide a tunable template for the subsequent deposition of ceramic films from aqueous solution under near ambient conditions. We will provide examples of finely controlled metal oxide deposition along with an extension of this chemistry to the surface modification of polymers and polymer composites.

  208. Chemistry Department Seminar

    "Spectroscopy of mass-selected metal clusters: electronic structure controls reactivity"

    Presented by Gerd Gantefor, University of Konstanz, Konstanz, Germany

    Monday, April 10, 2006, 1 pm
    Room 300, Bldg. 555

    Hosted by: Jim Lighstone

    Clusters made of simple metals like Gold or Aluminum exhibit a dramatic size dependence in their chemical reactivities. For these extremely small particles, electronic structure determines reactivity: e.g., Aun- and Agn- clusters show a pronounced even-odd alternation of O2 uptake, which can be directly related to their electron affinity /1/. Such very small particles show promising catalytic properties /2/, too, which motivates our research to gain a better understanding of the chemical properties of metal clusters. We study the dissociation dynamics of photoinduced reactions using time-resolved photoelectron spectroscopy. Absorption of a single photon results in the desorption of an O2 molecule from a metal cluster. This process of excitation and the subsequent dissociation is recorded by a sequence of photoelectron spectra. A second approach aims towards the chemical properties of deposited clusters. So far, the pronounced even-odd alternation of the chemical properties of the coinage metals has not been found for clusters interacting with a substrate. We studied the oxidation of size-selected Aun clusters deposited on Silicon oxide and found a low reactivity for Au5 and high reactivities for Au4 and Au6. On this substrate some of the interesting properties of free clusters seem to still be present. /1/ B. E. Salisbury, W. T. Wallace, R. L. Whetten, Chem. Phys. 262, 131 (2000) /2/ A. Sanchez, S. Abbet, U. Heiz, W.-D. Schneider, H. Häkkinen, R. N. Barnett, and U. Landman, J. Phys. Chem. A 103, 9573 (1999)

  209. Chemistry Department Seminar

    "Structure of TiO2 (110)-(1x2): formation of Ti2O3 one dimensional chains and the growth of subnanometer Si overlayers"

    Presented by Jose A. Gago, Institute of Materials Science, Madrid, Spain

    Monday, April 3, 2006, 4 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Jose A. Rodriguez

  210. Joint ESTD/Chemistry Seminar

    "In situ spectroscopy on Mars - following the water"

    Presented by Prof. h.c. Philipp Gutlich, Institut for Anorganische Chemie und Analytische Chemie Universitat Mainz

    Friday, March 31, 2006, 2 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Devinder Mahajan; Minfang Yeh

  211. Chemistry Department Seminar

    "Photocatalysis on Model Ti02 Surfaces"

    Presented by Dr. Michael Henderson, PNNL

    Wednesday, March 15, 2006, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Dr. Etsuko Fujita

  212. Chemistry Department Seminar

    "Modelling transition metals deposition on a support from first principles Molecular Dynamics simulations."

    Presented by Javier Fernandez-Sanz, University of Seville, Spain

    Wednesday, March 8, 2006, 11 am
    Room 300, Bldg. 555

    Hosted by: Dr. Jose Rodriguez

    Metal deposition constitutes one of the most appealing methods for the preparation of new materials of technological interest (catalysis, gas sensors, electronic devices,…). Addition of metal atoms to a surface can in principle look for different targets. Thus, a given relatively inert surface can be promoted by adding an alkali metal like Na. In another direction, specific catalysts are prepared by supporting transition metal atoms on inert surfaces. In these materials several questions are relevant from a microscopic point of view. First we are interested by the properties of the metal surface interface: the nature of the bond, the extension of the surface reduction, etc. Secondly, we would like to know the detailed structure of the particles adsorbed at the surface. This information could help for both a better understanding of the interface and a suitable description of the active sites in a given surface reaction. In this contribution we report on a theoretical work aimed to analyze these two aspects in catalytically relevant metal-support systems. Preferred sites and the nature of the metal-surface interaction has been analyzed by means of density functional based calculations under the GGA approach, using a periodic slab model of different thickness. The growth mechanism of Cu clusters on the surface at the early stages of deposition has been examined through BO molecular dynamics simulations. Some references: N. Cruz Hernández y J. Fdez. Sanz Molecular Dynamics Simulations of Pd Deposition on the α-Al2O3 (0001) Surface. J. Phys. Chem. B 2001, 105, 12111-12117. N. Cruz Hernández y J. Fdez. Sanz A first principles study of Cu atoms deposited on the α-Al2O3(0001) surface. J. Phys. Chem. B 2002, 106, 11495-11500. N. Cruz Hernández, Jesús Graciani, A. Márquez y Javier Fdez. Sanz Cu, Ag and Au atoms deposited on the α-Al2O3(0001) surface: a comparative density functional study Surf. Sci. 2005, 575, 189-196 J. F. Sanz y N. Cruz He

  213. Chemistry Department Seminar

    "Theory of nano-materials, spintronic materials, and nano-spintronic materials"

    Presented by Dr. Leeor Kronik, Weizman Institute of Science

    Friday, January 20, 2006, 11 am
    Hamilton Seminar Room, Bldg. 555

    Two exciting developments in the field of semiconductor science are the emergence of nano-materials and of spintronic materials. In nano-materials, size is used as a means of modifying systematically the electronic and optical properties of the material. In spintronic materials, addition of magnetic impurities can result in materials that are semiconducting and ferromagnetic at the same time. Here, I will present ab initio calculations for both classes of materials, based on density functional theory, that elucidate the mechanisms controlling size-induced and magnetic-impurity-induced changes in electronic structure. I will then show how these explain novel electrical, magnetic, and optical properties of these materials that have been observed experimentally. Finally, I will show how by modifying both size and impurity content we can predict unusual properties for “nano-spintronic” materials.

  214. Chemistry Department Seminar

    "An Atomic Scale View of Transition Metal Oxide Surfaces"

    Presented by Ulrike Diebold, Tulane University

    Wednesday, December 7, 2005, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Alex Harris

    Semiconducting transition metal oxides are used as bio-materials, in chemical sensors, for energy-related devices such as solar cells and photocatalysts, and represent an important class of optical and electronic materials. In many applications, surface and interface properties are critical to device functioning. Our research focuses on identifying the nano-scale properties of semiconducting oxides (e.g., TiO2, ZnO, SnO2) with Scanning Tunneling Microscopy and complementary surface spectroscopic techniques. Of particular interest are defects - either intrinsic ones such as missing atoms or step edges, or extrinsic dopants - and their influence on local electronic, geometric, magnetic, and chemical properties. The talk will give an overview of the power of scanning probe techniques to visualize surface atomic and electronic structure and will give examples of recent results.

  215. Poster Session

    "SUNY Students, Chemistry Department"

    Friday, December 2, 2005, 1:30 pm
    Lobby - Chemistry Bldg. 555

    Hosted by: Dr. Stan Wong, Stony Brook University & BNL

  216. Nuclear Chemistry/Physics Seminar

    "Recent Discoveries at the Relativistic Heavy Ion Collider"

    Presented by Dr. Kirill Filimonov

    Thursday, November 17, 2005, 11 am
    Bldg 555 - Room 300

    Hosted by: Mark Baker

    In recent years, experiments conducted at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory have made new discoveries in elucidating the properties of QCD matter at extremely high energy density. The bulk of the matter created in heavy-ion collisions has been shown to behave as a nearly ideal, non-viscous fluid, strikingly well described by relativistic hydrodynamics based on the QCD equation of state. The matter has been found to be extremely opaque to energetic partons revealing that the initial energy densities reached in heavy-ion collisions exceed 50-100 times that of ground state nuclei. I will present an overview of the results establishing the creation of hot and dense matter at RHIC, with a focus on the jet quenching and elliptic flow phenomena.

  217. Chemistry Department Seminar

    "Nanosecond Time-Resolved Infrared Spectroscopy: A Valuable Tool for the Investigation of Photoinduced Small Molecular Activations and Hydrogen Atom Transfers"

    Presented by David Grills, Brookhaven National Laboratory

    Tuesday, November 15, 2005, 1:30 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: John Miller

    Our research examines the fundamental chemistry underlying the efficient capture and storage of solar energy in useful chemical forms, with a focus on the mechanistic chemistry of transient species involved in homogeneous catalysis. In particular, we are interested in the photochemical activation of small, abundant molecules such as CO2, N2, hydrocarbons and H2O. An invaluable tool that we use to investigate these processes is nanosecond time-resolved step-scan FTIR spectroscopy (TR-S2FTIR). Bond formation between a transition metal center and a substrate is an important fundamental step in many catalytic reactions. In order to investigate the nature of these interactions with low-valent metal centers, we have investigated the thermodynamics, kinetics and isotope effects of photoinduced W-L bond cleavage and formation as a function of temperature and pressure, for the series of complexes, W(CO)3(PCy3)2L (Cy = cyclohexyl; L = H2, D2, C2H4, N2 [1] or CH3CN). The cleavage of C-H bonds is an important step in the catalytic conversion of hydrocarbons to higher value chemicals. Hydrogen atom transfer reactions are fundamentally important in a wide range of catalytic processes and there are many examples of metal-to-carbon H-atom transfers. However, the reverse reaction (carbon-to-metal H-atom transfer) has never been directly observed. We have used the metal radical, Cp(CO)2Os•, which was photogenerated from the metal-metal bonded dimer, [Cp(CO)2Os]2 to cleave C-H bonds of 1,4-cyclohexadiene. Using TR-S2FTIR, we were able to directly monitor, for the first time, the transfer of hydrogen atoms from a hydrocarbon to a metal center [2]. Kinetic studies revealed that the rate constant for this H-atom transfer process is surprisingly high, kH = 2.1 x 106 M-1 s-1. We have previously shown [3] that photolysis of the CO2 reduction catalyst, [Re(CO)3(dmb)]2 (dmb = 4,4’-dimethyl-2,2’-bipyridyl) in the presence of CO2 produces the radical species, Re(CO)3(dmb)S (S = coordinating

  218. Chemistry Department Seminar

    "Dynamics in hyper-rovibronic detail: Exploring the use of new commercial millimeter/sub-millimeter wavelength sources in traditional molecular reaction dynamics experiments."

    Presented by Liam Duffy, University of North Carolina at Greensboro

    Wednesday, November 9, 2005, 3 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Gregory Hall

    In our lab at UNCG we have implemented a molecular beam experiment that takes advantage of new millimeter / sub-millimeter wavelength technology in order to probe the products of photodissociation with ultrahigh energy resolution.1 The comparatively simple and inexpensive setup demonstrates the utility of combining commercial solid-state millimeter / sub-millimeter wavelength sources with hot-electron bolometer detectors to directly probe parent and product hyperfine rovibronic levels and their Doppler-resolved velocity distributions in a molecular beam. For example, in open-shell products with nuclear spin, the ultrahigh energy resolution of the rotational spectroscopy easily resolves nuclear quadrupole hyperfine structure and lambda doublets in both ground and excited spin-orbit states as well as in ground and excited vibrational levels. In this talk the technique is applied to the mode-specific photodissociation of OClO which has been the subject of many experimental and theoretical studies, driven in large part by the role it plays as a reservoir of free chlorine atoms in the stratosphere. The UV absorption spectrum of OClO from 270 to 470 nm displays a well-defined progression of predissociative vibrational levels in the excited A 2A2 electronic state. In the gas phase, it had been found that >96% of the parent molecules dissociate by the ClO (X 23/2,1/2) + O (3PJ) product channel and that the internal vibrational energy of the ClO product increases nearly linearly with increasing parent excitation.2,3 The photodissociation of OClO not only offers an opportunity test the experiment on a well-characterized molecular system, it is also particularly useful for demonstrating the type of dynamical information that may be extracted from the experiment and the extremely fine detail that may be achieved. Preliminary spectra from the experiment probe the product molecule’s electronic, vibrational, rotational, lambda doublet, and hyperfine state distributio

  219. Center for Functional Nanomaterials Seminar

    "Small is Different: Emergent Physics and Chemistry in the Nonscalable Regime"

    Presented by Uzi Landman, Georgia Institute of Technology

    Wednesday, October 26, 2005, 3 pm
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Jim Davenport

  220. Chemistry Department Seminar

    "Big Bang Chemistry - Exploring the Properties of Primordial Matter at RHIC"

    Presented by Ralf Averbeck, Stony Brook University

    Wednesday, October 19, 2005, 11 am
    Bldg. 555, Room 300

    Hosted by: Mark Baker

  221. Special Nuclear Chemistry/Nuclear Physics Seminar

    "Probing the Quark Gluon Plasma at RHIC with Jets"

    Presented by Dr. Jiangyong Jia, Columbia University

    Thursday, October 13, 2005, 3:30 pm
    Room 300, Bldg. 555

    Hosted by: Mark Baker

    A novel, hot and dense matter has been created in relativistic heavy ion collisions at Brookhaven National Laboratory. It's energy density and temperature are found to exceed the hadron to quark-gluon plasma phase transition values predicted by lattice QCD calculations. Significant progress has been made in understanding the properties of this matter in the past five years. I will show results from experiments at the Relativistic Heavy Ion Collider, focusing on the remarkable properties revealed by high transverse momentum hadrons and back to back hadron pairs.

  222. Chemistry Department Seminar

    "Designing Ligands to Capture the Sun"

    Presented by Randolph Thummel, University of Houston

    Friday, September 16, 2005, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Etsuko Fujita

  223. Summer Sundays

    "Bringing Chemistry to Life"

    Sunday, July 24, 2005, 10 am
    Berkner Hall Auditorium

    Why do some people crave chocolate, nicotine, and cocaine? Hear scientists describe efforts to understand the brain and addictions. See the fastest device in the country to study chemical reactions. Talk with researchers about the new field of nanoscience. Create a chemical reaction - make slime!

  224. Chemistry Department Seminar

    "Ionic Hydrogenolysis Reactions of Polyols - Some Crazy Ideas for New Approaches to Biomass Conversion"

    Presented by Marcel Schlaf, University of Guelph, Canada

    Monday, July 18, 2005, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: R. Morris Bullock

    Polyols of the general composition HOCH2(CHOH)nCH2OH (n = 1-4) are among the most abundant biomolecules on the planet and in principle constitute a renewable resource of C3 to C6 polymer building blocks, if new pathways and catalysts for their selective deoxygenation to the corresponding diols HOCH2(CH2)nCH2OH can be developed. The deoxygenations can be achieved through an iterative cascade of acid-catalyzed dehydration and metal catalyzed hydrogenation and hydrogenolysis reactions in the same reactor vessel. Some principle pathways of these reactions and specific guidelines for the design of catalysts capable of operating under the required acidic aqueous conditions will be discussed. A series of new metal-ligand bifunctional homogeneous catalysts meeting these guidelines are ruthenium complexes that incorporate chelating 2,2’-bipyridine and 1,10-phenanthroline ligands, ortho-functionalized with amino groups acting as internal proton acceptors/donors. The complexes are postulated to activate hydrogen gas in a heterolytic fashion and thus effect the hydrogenation and/or hydrogenolysis through a proton/hydride transfer, an ionic mechanism that should enable both a ionic hydrogenation of C=O and C=C double bonds and a ionic hydrogenolysis of aliphatic C-O ether bonds by the same catalyst system.

  225. Dr. Mow Lin Memorial Seminar Series

    "Chemistry and the Life in Extreme Environments"

    Presented by Eugene Premuzic, BNL-Retired

    Thursday, June 23, 2005, 11 am
    Hamilton Seminar Room, Bldg. 555

  226. Chemistry Department Seminar

    "The Hydricity of Transition-Metal Hydrides: Measurement, Controlling Factors, and Applications to Catalysis"

    Presented by Daniel DuBois, National Renewable Energy Laboratory

    Wednesday, June 8, 2005, 11 am
    Chemistry Department Bldg. 555, Room 300

    Hosted by: R. Morris Bullock

    Transition-metal hydrides are important intermediates in a large range of catalytic reactions. One of the defining characteristics of these compounds is their ability to act as hydride donors. In fact, it is this property for which they are named. However, reliable methods for experimentally determining the thermodynamic hydride donor ability of these compounds have only been developed in the past five years. The hydricity of a metal complex is defined in a manner strictly analogous to acidity. It is the free energy associated with the heterolytic cleavage of the M-H bond to form a metal fragment and a H- ion in solution. This presentation will describe various methods that have been developed in our group for determining this property. Contrary to previous expectations, the hydricity of a transition-metal hydride does not correlate with bond polarity or with the position of the metal in the periodic chart. Hydricity is not simply the inverse of acidity. In fact, these two properties can be independently controlled. Some of the factors that do control hydricity will be discussed. A knowledge of these factors has been used to: (1) Understand the stability of hydrides. (2) Design a new stoichiometric reaction for the room temperature hydrogenation of coordinated CO. (3) Design electrocatalysts for hydrogen oxidation and production. (4) Demonstrate the feasibility of forming boron-hydrogen bonds from hydrogen using transition metals as hydride transfer agents. Other potential applications include the development of transition-metal hydride catalysts for reactions in very acidic solutions, and the rational development of compounds for hydrogen separation applications. Finally, initial approaches to developing models that predict the thermodynamic properties of M-H bonds will be discussed.

  227. Chemistry Department Seminar

    "RHIC Results on the Thermochemistry and Hydrodynamics of the Strong Interaction"

    Presented by Peter Steinberg, Chemistry Department, Brookhaven National Laboratory

    Friday, May 20, 2005, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Richard Hahn

    There has been recent excitement about the growing consensus that collisions of gold ions at RHIC produce a hot, dense, and short-lived state of matter best described as a near-perfect fluid.The PHOBOS experiment at RHIC has contributed to this physics picture by measurements of bulk properties of the produced matter.This involves estimations of the initial state entropy via particle multiplicities, with areful attention paid to the role of the nuclear geometry, as well as studies of the collective hydrodynamical behavior of the matter as it evolves. PHOBOS has also observed interesting "scaling" behaviors, where certain properities appear to be invariant over a wide range of beam energies and system sizes,when viewed in the proper reference frame.Potential implications of these scaling rules will be discussed, in the context of results from PHOBOS and the other RHIC experiments as well as several theoretical approaches.

  228. Chemistry Department Seminar

    "Conjugated Organic Materials with Unusual Ground - and Excited-State Electronic Properties"

    Presented by Michael Therien, University of Pennsylvania

    Wednesday, May 4, 2005, 11 am
    Room 300, Chemistry Building 555

    Hosted by: John Miller

  229. Chemistry Department Seminar

    "Hybrization in Plants: Sex, drugs and resistance."

    Presented by Colin Orians, Dept of Biology, Tufts University

    Wednesday, April 13, 2005, 11 am
    Chemistry Bldg. Room 300

    Hosted by: Richard Ferrieri

  230. Chemistry Department Seminar

    "Redox Behavior & Reactivity of Ru Complexes with Oxyl Radical Ligands"

    Presented by Koji Tanaka, Institute for Molecular Science, Okazaki, Japan

    Friday, March 18, 2005, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Etsuko Fujita

  231. Chemistry Department Seminar

    "Fundamental Concepts in Reactivity & Catalysis of Alloy Surfaces"

    Presented by Bruce Koel, Depts of Chemistry & Materials Science & Lab for Molecular Robotics, Univ of Southern California, Los Angeles

    Wednesday, March 9, 2005, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Alexander Harris

    Achieving higher activity and selectivity of heterogeneous catalysts, electrocatalysts, and sensors requires advances in controlling structure and chemistry relevant to interfacial reactions at the nanoscale. One can now exploit an unprecendented ability to investigate such phenomena on ally surfaces to obtain new information about how and why composition, structure, and defects alter chemical reactions that occur at specific sites. We have been probing this "site-directed" chemistry at alloy surfaces in a wide range of chemisorption and catalytic reactivity studies. The talk will focus on how recent results for several Sn/Pt(111) and Sn/Pt(100) ordered surface alloys have helped to define the overall chemical reactivity of Pt-Sn bimetallic surfaces, clarified the role of a second metal in altering the chemistry of Pt alloys, and led to general principles for understanding the reactivity and selectivity of alloy catalysts. In addition, we have determined how to control formation of specific metal oxide nanostructures via oxidation of these alloys or by vapor deposition. Fundmental concepts emerging from all of these studies enhance our understanding and ability to tailor local properties of alloy and oxide surfaces, which should facilitate the design of new catalysts and sensors.

  232. Chemistry Department Seminar

    "Electrocatalysis at Electrode/Electrolyte Interface Based on Nanotechnology"

    Presented by Shaojun Dong, Changahun Inst of Applied Chemistry, Chinese Academy of Sciences, China

    Tuesday, March 8, 2005, 10 am
    Room 300, Chemistry Bldg. 555

    Hosted by: Alexander Harris

    Electrocatalysis at electrode/electrolyte interface is an important and long term topic from fundamental and practical point of view. Considerable current interest in electrocatalysis based on self-assembly and nanotechnology is ongoing challenge. The deliberate tailoring of nanostructured metallic catalysts at the monolayer-level could lead to new electronic and catalytic properties since surface-catalyzed reactions are extremely sensitive to the atomic- level details of the catalytic surface. In this report, we present a novel electrochemical strategy to nanoparticle-based catalyst design using the underpotential deposition (UPD), self-assembly and UPD with redox replacement technique from our laboratory.

  233. Chemistry Department Seminar

    "Some Aspects of Nanoelectrochemistry of Gold Nanoparticles and Their Derivatives"

    Presented by Erkang Wang, Changchun Inst of Applied Chemistry, Chinese Academy of Sciences, China

    Friday, March 4, 2005, 10 am
    Room 300, Chemsitry Bldg. 555

    Hosted by: Alexander Harris

    1. Proposing a dual energy barrier tunneling model to explain the imageability of the gold nanoparticles by STM. This model can also be used to construct multiple energy barrier structure on solid/liquid interface and to evaluate the electron transport ability of some monolayers of so-called “molecular wires” with electrochemical method. Thus we create the gold/molecular wire/gold sandwich like structures on gold electrode surface through molecular self-assembly and nanogold fabrication techniques. 2. Utilizing ITO-supported gold nanoparticle arrays as nanoelectrode arrays. Some conventional molecular self-assembly systems, such as monolayers of iodine, porphyrin monolayers and heteropoly acid, phospholipid/alkanethiol bilayers, 3-mercaptopropionicacid-bridged copper hexacyanoferrate multilayers, etc. can safely be transferred onto ITO-supported gold nanoparticle surfaces. 3. Gold nanoparticles can tune reactivities of electroactive species in solution and surface-bound proteins, which indicates that gold nanoparticles help heterogeneous electron tranfer. 4. ITO-bound gold nanoparticles can catalyze electroless deposition of gold to generate SPR-active electrode interface, which is used to investigate Ag UPD in-situ. 5. Utilizing gold nanoparticles as structural and functional units to deposit HRP on gold electrode surface, the resulted HRP/gold-nanoparticle electrode is a novel H2O2 biosensor with high stability. Acknowledgement: This work was supported by the National Natural Sciences Foundation of China

  234. Chemistry Department Seminar

    "The possibility of a dramatic improvement to the experimental limit on the electron's electric dipole moment using cold PbF molecules"

    Presented by Neil Shafer-Ray, Dept of Physics and Astronomy, University of Oklahoma

    Thursday, February 17, 2005, 1 pm
    Room 300, Building 555

    Hosted by: Greg Hall

    The possibility of an electron electric dipole moment (EDM) is predicted by current theories of physics, including the Standard Model. Whereas the value predicted by the Standard Model (~10^-38 e cm) is beyond the reach of current experiment, most other theories, including Supersymmetry, predict a dipole moment close to that of the current limit (10^-27 e cm). Thus the search for an electron EDM is an important test of theories beyond the Standard Model. I show that PbF molecules cooled to 0.1 mK and confined by a spatially varying electric field will be sensitive to an electric dipole moment of the order of 10^-31 e cm. Thus a three- to four-order-of-magnitude improvement in the current limit would be possible with the construction of a decelerator capable of reducing the speed of a cold molecular beam of PbF. A similar a machine has already been built by others (Tarbutt et al, PRL 92 2004 (173002)) to decelerate a beam of YbF. The slowing techniques used are remarkably similar (up to an important sign difference) to those used in high energy physics. Thus the next dramatic improvement in the experimental limit on the electric EDM is likely to come from the accelerator physics community.

  235. Chemistry Department Seminar

    "Density functional studies in heterogeneous catalysis and nanoscience"

    Presented by Ping Liu, Chemistry Department, BNL

    Wednesday, February 9, 2005, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: Jon Hanson

    Density functional theory has reached a level where it can be used to describe complete catalytic reactions on both surfaces and nanoparticles. This gives a basic insight into these processes, and it allows us to pinpoint the origin of the catalytic activity of the material. The reactions involving in PEM fuel cell and hydrodesulfurization are used to exemplify the approach. It will be shown that by combining density functional calculations with kinetic modeling we can well predict the catalytic activities of different systems. This provides a strong basis for rational catalyst design.

  236. Atmospheric Sciences Division Seminar

    "Modeling of Nitrate and Ammonium in a Global Aerosol/Chemistry Model"

    Presented by Yan Feng, University of Michigan

    Monday, December 6, 2004, 11 am
    Building 815E Conference Room

  237. Chemistry Department Seminar

    "Molecular Secrets from High Resolution Spectroscopy in the Gas Phase"

    Presented by David Pratt, Chemistry Department, University of Pittsburgh

    Wednesday, November 24, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  238. Center for Functional Nanomaterials and Computational Science Seminar

    "Multi-Scale Modeling and Quantum Chemistry via Genetic Programming (Machine-Learning) Methods"

    Presented by Duane D. Johnson, University of Illinois Urbana-Champaign, The Frederick Seitz Materials Research Laboratory

    Monday, November 22, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  239. Atmospheric Chemistry, Aerosols, and Climate Change Symposium

    "In honor of Carmen Benkovitz on the occasion of her retirement from Brookhaven National Lab"

    Presented by Various speakers, see agenda

    Thursday, November 18, 2004, 4 am
    Hamilton Seminar Room, Bldg. 555

  240. Center for Functional Nanomaterials and Chemistry Department Seminar

    "Gatekeeping Effect: Multi-Functionalized Mesoporous Silica Nanomaterials for Catalysis, and Biotechnical Applications"

    Presented by Victor Lin, Iowa State University

    Monday, November 15, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  241. Chemistry Department Seminar

    "New Research Directions Enabled by Nanostructered Oxide Solids"

    Presented by Suhas Bhandarkar, Materials Science & Engineering Department, Alfred University

    Wednesday, November 3, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  242. Chemistry Department Seminar

    "Molecular electronics based on conjugated diblock co-oligomers"

    Presented by Luping Yu, Department of Chemistry, University of Chicago

    Wednesday, October 6, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  243. Chemistry Department Seminar

    "Interactions between prefrontal cortex and amygdala: Relevance to the pathophysiology of schizophrenia"

    Presented by Anthony Grace, Department of Neuroscience, University of Pittsburgh

    Monday, September 27, 2004, 3 pm
    Room 300, Chemistry Bldg 555

  244. Chemistry Department Seminar

    "Ultrafast Electron Transfer Across the Molecule-Nanoparticle Junction"

    Presented by Tim Lian, Emory University Chemistry Dept.

    Wednesday, September 22, 2004, 1 am
    Hamilton Seminar Room, Bldg. 555

  245. Chemistry Department Seminar

    "Characterization of Novel Anode and Cathode Electrocatalysts"

    Presented by Jingguang Chen, Department of Chemistry, University of Delaware

    Wednesday, August 4, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  246. Chemistry Department Seminar

    "Synthesis of Glucocorticoid Ligans as Potential PET Imaging Agents"

    Presented by Robert Hoyte, Georgetown University

    Wednesday, July 21, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  247. Chemistry Symposium

    "International Symposium on Ultrafast Accelerators for Pulse Radiolysis"

    Presented by James Wishart, BNL, Chemistry Department

    Monday, June 28, 2004, 8:30 am
    Chemistry, Room 300

  248. Chemistry Symposium

    "International Symposium on Ultrafast Accelerators for Pulse Radiolysis"

    Presented by James Wishart, BNL Chemistry Department

    Saturday, June 26, 2004, 8:30 am
    Hamilton Seminar Room, Bldg. 555

  249. Chemistry Symposium

    "International Symposium on Ultrafast Accelerators for Pulse Radiolysis"

    Presented by James Wishart, BNL, Chemistry Department

    Saturday, June 26, 2004, 8:30 am
    Hamilton Seminar Room, Bldg. 555

  250. Chemistry Symposium

    "International Symposium on Utrafast Accelerators for Pulse Radiolysis"

    Presented by James Wishart, BNL Chemistry Department

    Friday, June 25, 2004, 5 pm
    Hamilton Seminar Room, Bldg. 555

  251. Chemistry Department Seminar

    "Later, First Row Oxo, Imido, and Carbene Complexes: From Novel Structures to Catalytic Group Transfer"

    Presented by Timothy Warren, Georgetown University

    Wednesday, June 16, 2004, 1 am
    Hamilton Seminar Room, Bldg. 555

  252. Medical Department Seminar

    "Guanidines, Estrogens and Benzoxazoles: From cold to (almost) hot chemistry"

    Presented by Andrew Gibbs, Lawrence Berkeley National Laboratory

    Friday, May 28, 2004, 1:30 pm
    Large Conference Room, Bldg. 490

  253. Chemistry Department Seminar

    "Photoinduced Charge Carrier Generation"

    Presented by Masanori Tachiya, National Institute of Materials Chemistry, Japan

    Friday, May 7, 2004, 1:30 pm
    Hamilton Seminar Room, Bldg. 555

  254. Environmental Sciences Department Seminar

    "Sea Salt Aerosol: Clouds, Chemistry and Climate"

    Presented by Ernie Lewis, Atmospheric Sciences Division

    Tuesday, May 4, 2004, 11 am
    Building 815E Conference Room

  255. Chemistry Department Seminar

    "Carbonic Anhydrase & Isotope Effects"

    Presented by David Silverman, University of Florida, Gainesville

    Wednesday, April 28, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  256. Chemistry Department Seminar

    "Static and Dynamical Solvation at Liquid Interfaces Probed by Second Nature Harmonic Generation"

    Presented by Xiaoming Shang, Columbia University

    Thursday, April 22, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  257. Chemistry Department Seminar

    "The Surface Reactions of TiO2 & UO2 single crystals: The role of surface defects."

    Presented by Hicham Idriss, University of Auckland, New Zealand

    Wednesday, April 21, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  258. Chemistry Department Seminar

    "The Development of Strategies for the Preparation of Designed Supermolecular Structures"

    Presented by William Fowler, State University of New York, Stony Brook

    Thursday, April 8, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  259. Chemistry & Environmental Sciences Joint Workshop

    "Informational Workshop on Chemistry & Applications of Ionic Liquids"

    Presented by James Wishart, Chemistry and Environmental Science Departments, BNL

    Wednesday, April 7, 2004, 10 am
    Hamilton Seminar Room, Bldg. 555

  260. Chemistry Department Seminar

    "Probing Molecular Structure, Dynamics, and Intermolecular Interactions Using Photons and Electrons"

    Presented by Gloria Florio, Columbia University, Department of Chemistry

    Thursday, March 25, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  261. Chemistry Department Seminar

    "Condensed Matter Research at the Intense Pulsed Neutron Source (IPNS)"

    Presented by Raymond Teller, Intense Pulsed Neutron Source, Argonne National Laboratory

    Wednesday, March 24, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  262. Chemistry Department Seminar

    "Probing Reactions with Fast and Ultrafast Time-resolved IR Spectroscopy in Conventional & Supercritical Fluids: From Organometallic Alkane & Noble Gas Complexes to IR probes of DNA Damage"

    Presented by Michael George, University of Nottingham, United Kingdom

    Friday, March 12, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  263. Chemistry Department Seminar

    "Fluorescent Detection of Hazardous Materials: Light, Zeolites, and Sunlight"

    Presented by Mark Spitler, President & Research Fellow, ChemMotif, Inc.

    Thursday, March 11, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  264. Lunchtime Tour

    "Tour the Chemistry Department and the Laser Electron Accelerator Facility"

    Presented by Contact Elaine Lowenstein, x2400

    Friday, January 30, 2004, 12 pm
    Meet in Berkner Lobby

  265. Chemistry Department Seminar

    "Structure & Reactivity of Open-Shell Complexes:A New Frontier in Atmospheric Chemistry"

    Presented by Joseph Francisco, Purdue University

    Wednesday, January 21, 2004, 11 am
    Hamilton Seminar Room, Bldg. 555

  266. Chemistry Department Seminar

    "Radiological Safety, Dosimetry and Protection Strategies"

    Presented by Michael Ryan, Editor-in-Chief, Health Physics Journal

    Monday, January 12, 2004, 11 am
    Conference Room A/B, Bldg. 490

  267. Chemistry Department Seminar

    "Ultrafast High Energy Chemistry & the Development of Laser Based Femtosecond X-Ray and Electron Sources"

    Presented by Robert Crowell, Argonne National Laboratory

    Friday, December 19, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  268. Chemistry Department Seminar

    "Structure and Dynamics of Barrier Transition States"

    Presented by Xueming Yang, IAMS, Taiwan

    Thursday, December 18, 2003, 4 pm
    Chemistry 300

  269. Chemistry Department Seminar

    "New Surface Design of Photoreactive Monolayers for Adsorption Control of Nanoscale Materials"

    Presented by Masaru Nakagawa, Tokyo Institute of Technology, Japan

    Friday, December 5, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  270. Chemistry Department Seminar

    "A Celebration of BNLs Ralph Weston at Eighty"

    Presented by Various

    Wednesday, December 3, 2003, 2 pm
    Hamilton Seminar Room, Bldg. 555

  271. Chemistry Department Seminar

    "The Growth of Reactivity of Metal Particles TiO2(110)"

    Presented by Donna Chen, University of South Carolina

    Wednesday, November 19, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  272. Chemistry Department Seminar

    "Non-Adiabatic Effects in the Spectroscopy and Scattering of NO-Rare Gas Complexes"

    Presented by Henning Meyer, Dept. of Physics & Astronomy, University of Georgia

    Wednesday, November 5, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  273. Chemistry Department Seminar

    "Characterization of Molybdenum Catalysts using Temperature-Programmed Reduction and Time-Resolved X-ray Diffraction"

    Presented by Edwin Kugler, West Virginia University

    Thursday, October 30, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  274. Chemistry Department Seminar

    "Intro to experimental apparatus of the pulse radiolysis facility ELBENA at the Hahn-Meitner Institute and"

    Presented by Eberhard Janata, Hahn-Meitner Institute, Berlin, Germany

    Thursday, October 23, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  275. National Synchrotron Light Source Seminar

    "FTIR Microscopy and Combinatorial Chemistry"

    Presented by Gurjit Mandair, University of Southampton, United Kingdom

    Tuesday, October 7, 2003, 10:30 am
    Seminar Room, Bldg. 725

  276. Chemistry Department Seminar

    "Spectroscopy and dynamics of the AI-H2/D2 van der Waals complex"

    Presented by Xiaofeng Tan, Johns Hopkins University

    Thursday, September 25, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  277. Chemistry Department Seminar

    "New Results from the Sudbury Neutrino Observatory: Measurement of the Total Active 8-B Solar Neutrino Flux with Enhanced Neutral Current Sensitivity"

    Presented by Richard L. Hahn, BNL Chemistry Department

    Wednesday, September 17, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  278. Chemistry Department Seminar

    "Main-Chain FLC Polymers for Electronic Nonlinear Optics Applications"

    Presented by David Walba, University of Colorado

    Friday, September 12, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  279. Chemistry Department Seminar

    "Understanding Charge Transport at Molecule-Metal Junctions: A Spectroscopic Approach"

    Presented by Xiaoyang Zhu, University of Minnesota

    Friday, September 5, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555

  280. Chemistry Department Workshop

    "BNL Workshop to Discuss Future Non-DOE Funding Opportunities in Plant Biology"

    Presented by Richard Ferrieri, Chemistry Department

    Friday, August 15, 2003, 11 am
    Chemistry Bldg., Room 300

  281. Chemistry Department Seminar

    "The NMR Shutter-Speed: From Chemistry to Cancer, and Beyond"

    Presented by Charles Springer, Jr., BNL Chemistry Department

    Wednesday, August 13, 2003, 4 pm
    Hamilton Seminar Room, Bldg. 555

  282. National Synchrotron Light Source Symposium

    "Carboxylate Chemistry on Titania: Thermal and Photochemical"

    Presented by J.M. White, University of Texas

    Tuesday, August 12, 2003, 10:30 am
    Seminar Room, Bldg. 725

  283. Chemistry Department Seminar

    "Radiation Chemistry Research at Pune University"

    Presented by Mahava Rao Balijepalli, Pune University, India

    Monday, June 30, 2003, 11 am
    Hamilton Seminar Room, Bldg. 555