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September 2020
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  1. Center for Functional Nanomaterials Seminar

    8:30 am, https://teams.microsoft.com/l/meetup-join/19%3amee

    Hosted by: Dr. Charles Black

    Novel functional materials are usually characterized by emerging ordering in atomic and electronic structures beyond the conventional unit-cell level. Examples include artificial superlattices, self-assembled nanostructures, ferroic domain structures, and charge-density waves. Such complex ordering gives rise to large supercells containing too many atoms, making it a formidable task for diffraction-based structure determination. On the other hand, the maturation of aberration-corrected TEM/STEM presents an alternative real-space approach to probe the complex ordering, through directly imaging the atomic structure with picometer precision, as well as the spatially-resolved spectroscopy to map the electronic structure. Here I will give several examples showing the power of advanced STEM on resolving the complex ordering: i) By developing an imaging condition optimized for oxygen contrast, we can image sensitively the octahedral structure in perovskite oxides with picometer precision. It further enabled us to reveal an extraordinary 2D ordered octahedral tilting in the solid electrolyte Li0.5-3xNd0.5+xTiO3, and to demonstrate its dependence on the competition between Li% and lattice strain.[1] ii) Through atomic displacement mapping using high-resolution imaging, and electric polarization mapping based on 4D-STEM, we made the first experimental discovery of 2D antiferroelectricity in In2Se3, and resolved the true nature of its superstructure that had been under debate for over four decades.[2] iii) In the last example, we applied atomic-scale electron energy-loss spectroscopy to unravel the distinct configurations and valence states of Ce dopants in Mn3O4 nanocatalysts, which suggested an effective oxygen-storage/release route that is responsible for the enhanced redox catalytic activity from Ce doping.[3] [1] Nature Materials 14, 1142-1149 (2015). [2] Physical Review Letter 125, 047601 (2020). [3] Chemistry of Material 31, 5769-5777 (2019).

  2. CFN Virtual Colloquium

    4 pm, BlueJeans Event: https://primetime.bluejeans.com/

    Hosted by: Chang-Yong Nam

    Macromolecular self-assembly has evolved to become an important and valuable tool for bottom-up patterning and fabrication at the nanometer scale. From block copolymer lithography to nanocrystal superlattices to biomolecular assemblies, bottom-up patterning is reaching an unprecedent level of control over complex patterns at the nanoscale with an increasing degree of precision. There is no question that the lithographic landscape has been transformed in the past few years with the introduction of extreme ultraviolet (EUV) lithography and the maturity of multiple patterning techniques. At dimensions below 10 nm, emphasis is shifting away from resolution to precision, highlighting the importance of the uniformity achieved by block copolymers and the exquisite precision afforded by biomolecular assemblies. Moreover, an opportunity may be opening for new, higher complexity, information-rich architectures where hybrid nanoparticle-(bio)molecule assemblies may shine. With features defined at the molecular level and the potential to modular and hierarchical structures, self-assembly offers a path to highly uniform, 2D and 3D architectures. In this talk I will review the current state of bottom-up patterning with soft matter and I will discuss research plans at The Molecular Foundry related to molecular-scale assembly hoping we can foster collaborations across the various NSRCs. Bio-sketch: Dr. Ricardo Ruiz is a Staff Scientist at Lawrence Berkeley National Laboratory where he uses Soft Matter Physics to solve nanofabrication challenges at the single-digit nm scale. From 2006 to 2019 he held various appointments at Hitachi GST/ HGST/ Western Digital where he contributed to magnetic bit patterned media and non-volatile memories, and he managed a research Group dedicated to block copolymer and nanoparticle lithography. He received his PhD in Physics from Vanderbilt University in 2003. He is a Fellow of the American Physical Society. To join, select from the following options: 1) Web Browser a) https://primetime.bluejeans.com/a2m/live-event/ygxfdcgf 2) Laptop paired with room system (Best Experience) a) Dial: bjn.vc or 199.48.152.152 in the room system. b) Go to https://primetime.bluejeans.com/a2m/live-event/ygxfdcgf/room-system/ c) Enter the pairing code displayed on your room system screen into your browser. 3) Room System a) Dial: bjn.vc or 199.48.152.152 in the room system. b) Enter Meeting ID: 149812585 and Passcode: 5815 4) Joining via a mobile device? a) Open this link : https://primetime.bluejeans.com/a2m/live-event/ygxfdcgf b) Download the app if you don't have it already. c) Enter event ID : ygxfdcgf 5) Phone Dial one of the following numbers, enter the participant PIN followed by # to confirm: +1 (415) 466-7000 (US) PIN 9862228 # +1 (760) 699-0393 (US) PIN 2298814590 # 6) Joining from outside the US? https://www.bluejeans.com/numbers/primetime-attendees/event?id=ygxfdcgf

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  1. Center for Functional Nanomaterials Seminar

    2 pm, ZoomGov - https://bnl.zoomgov.com/j/1606431928

    Hosted by: Mircea Cotlet

    The efficient transport and interconversion of energy between photons and matter underpins life on earth, and inspires modern technology. Contrary to natural systems, however, in modern energy conversion systems ranging from solar panels to computers, semiconductors to photocatalysts, energy moves slowly, randomly and often inefficiently towards target conversion sites. My work aims to investigate how energy can be directed in molecules and materials in ways that are efficient and targeted, moving beyond stochastic fluctuation driven energy migration. My comprehensive research in the multidimensional ultrafast electronic spectroscopic of functional materials, natural photosynthetic proteins, and photocatalysts has set important precedents in this direction. In a recent study, we discovered how quantum nuclear vibrations participate during a photoinduced electron transfer reaction like a sequence of ratchets, progressively enhancing electron transfer efficiency and rate (submitted). By studying nuclear coherences, we were able to measure unprecedented dynamics along three distinct reaction coordinates for an intermolecular ET reaction. This electronic-nuclear interplay often manifests in the form of an anomalous dispersion of nuclear coherences coupled to the reaction (JACS, 2019). Our breakthrough work on reactivity of transition metal photocatalysts unraveled how quantum vibrational coupling can lead to selective and targeted bond activation (Chem, 2019). We were able to show that quantum vibrational coupling can acts as a conduit to shuttle energy from light absorbing moiety of the transition metal complex to the active reaction site. We also showed that a directional electron density and energy migration from light absorbing ligands to the functional site opens a controlled photoactivation pathway (JACS 2018). The insights from these and other works strongly indicate that exploiting order/synchronization provided by electronic-nuclear interdependencies can help extracting more energy from solar light conversion, speeding up quantum information transport, enhancing carrier transport, and increasing photocatalytic efficiency.

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  1. Center for Functional Nanomaterials Seminar

    2 pm, ZoomGov - https://bnl.zoomgov.com/j/1604642090

    Hosted by: Mircea Cotlet

    The first demonstration of transient demagnetization after femtosecond optical excitation was a seminal achievement in condensed matter physics that led to the birth of the field of ultrafast magnetism. Today, we continue to work towards unravelling the nature of the mechanisms that underlie these processes and develop methods for exploiting them to harness new magnetic phenomena. With the recent emergence of quantum material systems hosting novel intrinsic magnetic order, we now have an exciting new playground to study the transient interactions between photons and spin excitations and phases. In this talk, I will discuss our efforts in using such systems to both control the properties of electromagnetic radiation and coherently drive collective magnetic phenomena with light, focusing on three examples. First, I will highlight our efforts aimed at manipulating terahertz pulses by leveraging magneto-plasmonic resonances in micro-structured graphene. I will then examine how light can be used to directly manipulate magnetic order. Here, ultrafast optical quenching of magneto-crystalline anisotropy in the multiferroic skyrmion-host GaV4S8 can drive coherent collective breathing and rotational skyrmion lattice excitations. Finally, I will discuss our recent work involving the ferromagnetic van der Waals crystal CrI3. Our experiments shed light on the nature of angular momentum transfer in this material and reveal a strong coupling between the spin and lattice degrees of freedom. This manifests as coherent spin-coupled phonons whose vibrational amplitude is highly sensitive to the helicity of the driving optical pulse. Together, these three examples codify the immense promise that ultrafast optics holds in understanding and utilizing the novel magnetic properties of quantum materials. Moreover, they point a path towards generating dynamic states with light that may be the key to unlocking the next generation of high-speed memory and nanoscale magneto-optical technology.

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  1. Center for Functional Nanomaterials Seminar

    2 pm, ZoomGov - https://bnl.zoomgov.com/j/1608737754

    Hosted by: Mircea Cotlet

    Low dimensional nanomaterials, like zero-dimensional quantum dots (QDs) and two-dimensional van der Waals materials (2D-vdW), have aroused strong research interest owing to their fascinating electrical, optical, and magnetic properties. Optoelectronic properties of these low dimensional nanomaterials are important for exploring their applications in a wide range such as photovoltaics, photodetectors, light emitting diodes and quantum information. In this talk, I will first discuss optoelectronic characterizations of hybrids composed by QDs and 2D-vdW using home-built scanning photocurrent microscope, demonstrating the potential applications in photovoltaics and photodetectors. Then I will show the enhancement in optoelectronic properties of 2D materials through self-assemble. In the last part, I will discuss the future facility developments and research directions in this fascinating and promising research area.

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  1. SEP

    29

    Tuesday

    Center for Functional Nanomaterials Seminar

    10 am, ZoomGov: https://bnl.zoomgov.com/j/1609679957

    Tuesday, September 29, 2020, 10:00 am

    Hosted by: Oleg Gang

    Rapid and accurate identification of the pathogen(s) responsible for infection is a critical step in determining an effective treatment and thus impacting patient outcomes. Molecular diagnostics (MDx) can identify infecting species in times as short as hours or less. However, the fundamental complexity of current MDx modalities has hindered their widespread clinical use in point-of-care (PoC) applications. This talk is about developing both the fundamental understanding and the technology associated with a new materials platform compatible with PoC pathogen detection. Our approach exploits electron-beam lithography to pattern functional poly(ethylene glycol) [PEG] microgels. Their functionality enables oligonucleotide tethering that achieves liquid-like hybridization and enzymatic amplification on a solid substrate. We use patterned microgels to integrate a novel combination of self-reporting molecular beacons, self-assembled dielectric microlenses, and solid-phase and/or solution-phase nucleic-acid amplification primers in a viral-detection microarray model. Importantly, tethered microlenses effectively increase the numerical aperture of the collection optics and can increase the collected fluorescent signal by as much as 10 times. The assays give attomolar sensitivity. The assays are validated with three different and clinically important respiratory viruses: influenza A virus (Flu A); influenza B virus (Flu B); and respiratory syncytial virus (RSV). We furthermore demonstrate the surface patterning of discrete microgels with orthogonal chemical functionality, induced by dose-dependent radiation chemistry, which open possibilities to differentially locate bioactive species for amplification and detection. Finally, we introduce a new concept of patterning functional microgels in the form of covalently connected microgel strings with complex 3-D morphology, which manifest macromolecular conformational properties at an entirely new length scale (~10-100 μm) and open new opportunities to create diagnostic spots with 3-D rather than just 2-D structure.

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  1. SEP

    29

    Tuesday

    Center for Functional Nanomaterials Seminar

    "Surface Patterning of Functional Microgels and Their Application to Molecular Diagnosis of Respiratory Virus Infections"

    Presented by Feiyue Teng, Chemical Engineering and Materials Science, Stevens Institute of Technology

    10 am, ZoomGov: https://bnl.zoomgov.com/j/1609679957

    Tuesday, September 29, 2020, 10:00 am

    Hosted by: Oleg Gang

    Rapid and accurate identification of the pathogen(s) responsible for infection is a critical step in determining an effective treatment and thus impacting patient outcomes. Molecular diagnostics (MDx) can identify infecting species in times as short as hours or less. However, the fundamental complexity of current MDx modalities has hindered their widespread clinical use in point-of-care (PoC) applications. This talk is about developing both the fundamental understanding and the technology associated with a new materials platform compatible with PoC pathogen detection. Our approach exploits electron-beam lithography to pattern functional poly(ethylene glycol) [PEG] microgels. Their functionality enables oligonucleotide tethering that achieves liquid-like hybridization and enzymatic amplification on a solid substrate. We use patterned microgels to integrate a novel combination of self-reporting molecular beacons, self-assembled dielectric microlenses, and solid-phase and/or solution-phase nucleic-acid amplification primers in a viral-detection microarray model. Importantly, tethered microlenses effectively increase the numerical aperture of the collection optics and can increase the collected fluorescent signal by as much as 10 times. The assays give attomolar sensitivity. The assays are validated with three different and clinically important respiratory viruses: influenza A virus (Flu A); influenza B virus (Flu B); and respiratory syncytial virus (RSV). We furthermore demonstrate the surface patterning of discrete microgels with orthogonal chemical functionality, induced by dose-dependent radiation chemistry, which open possibilities to differentially locate bioactive species for amplification and detection. Finally, we introduce a new concept of patterning functional microgels in the form of covalently connected microgel strings with complex 3-D morphology, which manifest macromolecular conformational properties at an entirely new length scale (~10-100 μm) and open new opportunities to create diagnostic spots with 3-D rather than just 2-D structure.

  2. OCT

    1

    Thursday

    CFN Virtual Colloquium

    "Hyperuniform States of Matter and Their Novel Bulk Properties"

    Presented by Salvatore Torquato, Princeton University

    4 pm, TBD

    Thursday, October 1, 2020, 4:00 pm

    Hosted by: Alexei Tkachenko

    The hyperuniformity concept provides a unified means to classify and structurally characterize all perfect crystals, perfect quasicrystals, and exotic disordered states at large length scales. Disordered hyperuniform many-particle systems [1,2] can be regarded to be new states of disordered matter in that they behave more like crystals or quasicrystals in the manner in which they suppress large-scale density fluctuations, and yet are also like liquids and glasses because they are statistically isotropic structures with no Bragg peaks. Thus, these special correlated disordered materials possess "hidden order" that is not apparent on large length scales. A variety of groups have discovered that disordered hyperuniform materials possess desirable photonic and electronic bandgap properties [2]. More recently, we have shown that they possess nearly optimal transport and elastic properties [3,4]. I will review the salient ideas behind the hyperuniformity concept and procedures to design a variety of different disordered hyperuniform materials as well as their corresponding physical properties, including novel electromagnetic, transport and mechanical characteristics. It has been a challenge to create very large samples, either numerically or experimentally, that are hyperuniform with high fidelity. I will discuss recent progress that we have made in this direction [5,6] and its implications for novel physical properties. 1. S. Torquato and F. H. Stillinger, "Local Density Fluctuations, Hyperuniform Systems, and Order Metrics," Phys. Rev. E, 68, 041113 (2003). 2. S. Torquato, "Hyperuniform States of Matter," Phys. Reports, 745, 1 (2018). 3. G. Zhang, F. H. Stillinger, and S. Torquato, "Transport, Geometrical, and Topological Properties of Stealthy Disordered Hyperuniform Two-phase Systems," J. Chem. Phys., 145, 244109 (2016). 4. S. Torquato and D. Chen, "Multifunctional Hyperuniform Cellular Networks: Optimality, Anisotropy and Disorder," Multifunctional Materials, 1, 015001 (2018). 5. D. Chen, E. Lomba and S. Torquato, "Binary Mixtures of Charged Colloids: A Potential Route to Synthesize Disordered Hyperuniform Materials," Phys. Chem. Chem. Phys. 20, 17557 (2018). 6. Z. Ma, E. Lomba, and S. Torquato, Optimized Large Hyperuniform Binary Colloidal Suspensions in Two Dimensions, Phys. Rev. Lett., 125 068002 (2020).