By Qun Shen
Exciting research opportunities at NSLS-II drew more than 260 participants to a workshop at Brookhaven Lab from August 12-13, 2013, where NSLS users planning to continue their work at NSLS-II joined prospective NSLS-II users to hear talks and debate possible early science experiments. The workshop marked the beginning of the process to create a pool of experiment proposals and form research teams.
The many presentations at each breakout session yielded discussions on which experiments promise to have the greatest science impact and take best advantage of NSLS-II’s world-leading capabilities. Those chosen will run on an initial suite of seven beamlines (out of about 58 beamlines when the facility is fully built out) and will aid in the NSLS-II science commissioning phase, expected to begin in late 2014.
Brookhaven Lab Director Doon Gibbs welcomed workshop participants, followed by an introduction from Associate Laboratory Director for Photon Sciences Steve Dierker, who briefed attendees on the NSLS-II construction status and operations timeline. Then, a series of science talks delved into the “grand challenge” problems in science that NSLS-II will help to address: Sunil Sinha, University of California, San Diego, “Complexity and Dynamics in Condensed Matter Systems;” Gayle Woloschak, Northwestern University, “Nanoparticles in Functional Biological Systems;” and John Sarrao, Los Alamos National Laboratory, “Materials Coâ€design at the Mesoscale: Opportunities for NSLSâ€II.” Following these presentations, Paul Zschack, deputy director of the Photon Division within the Photon Sciences Directorate, discussed the capabilities of the initial suite of NSLS-II beamlines.
The “meat” of the workshop was found in the six breakout sessions on day two and the conversations that took place within them. The sessions represented six of the first seven beamlines: Hard X-ray Nanoprobe (HXN), Submicron Resolution X-ray (SRX) spectroscopy, Coherent Hard X-ray (CHX) scattering, Coherent Soft X-ray scattering branch beamlines 1 and 2 (CSX1 and CSX-2), and X-ray Powder Diffraction (XPD). A separate session for the Inelastic X-ray Scattering (IXS) beamline was held at Brookhaven on October 1.
The topics covered ranged from materials complexity and dynamics to basic needs for conducting advanced studies of functional materials systems, such as fuel cells and energy-storage schemes.
Some specific science themes emerged as well. One was “mesoscale” science – a new frontier for research, which examines the properties and phenomena that occur at the border between the quantum world of assemblies of single atoms and the complex world of functional systems.
The breakout session discussions were also a starting point for the formation of research teams that will best achieve the research goals at NSLS-II, focusing on the areas of theory and analysis, ancillary measurements, and specimen environment development.
All the breakout sessions were well attended and yielded some excellent dialogue.
At the HXN session, 50 registered participants took in presentations by 14 invited speakers, representing many scientific fields. These included materials science, condensed matter physics, high-pressure science, nanoelectronics, diffraction theory/techniques, and x-ray diffraction microscopy techniques.
HXN beamline scientists Yong Chu and Hanfei Yan explained HXN’s planned scientific capabilities, which include high spatial resolution (10 nanometers or better); the ability to take parallel measurements of two or more techniques; in-situ sample environments (temperature, pressure, electric or magnetic fields); and excellent stability, which allows routine applications of ptychography and other advanced x-ray microscopy techniques. Attendees repeatedly cited many of these capabilities during the presentations and the follow-up discussions, which yielded several possible directions for first experiments.
Kyle Brinkman (Savannah River National Laboratory) talked about studies of mixed ionic and electronic membrane systems; Wenge Yang (Carnegie Institute of Washington) later elaborated on the scientific opportunities for high-pressure science. Wilson Chiu (University of Connecticut), Esther Takeuchi (Stony Brook University and Brookhaven), and Kyung-Wan Nam (Brookhaven) discussed scientific problems facing the development of solid-oxide fuel cells and battery materials, some of which may be addressed at HXN.
Qingteng Zhang (University of Wisconsin) and Stephan Hruszkewycs (Argonne National Laboratory) discussed current state-of-the-art experiments on ferroelectric materials and possible early-science experiments on ferroelectric domain dynamics and nanostructure. In related work, Oleg Shpyrko (University of California, San Diego) talked about future scientific opportunities for investigating magnetic domains. Conal Murray (IBM) discussed how he could use the HXN beamline to solve industrial problems facing nanoelectronics.
Like HXN, the XPD session was also attended by a large audience, with some participating via webcast. The XPD beamline will offer unprecedented resolution performance while maintaining high levels of photon flux in the 30-70 keV x-ray energy range. It will be a versatile, modular, high-energy x-ray diffraction and imaging instrument for real- and reciprocal-space diffraction studies of real materials in real time, under real conditions.
The session repeatedly touched on the frontier of materials science research. Many scientists are working to develop transformational materials for energy production and energy storage; the tools at XPD will further these types of studies. An example is the work presented by John Parise (Stony Brook University) on high-pressure syntheses of novel oxynitride photocatalysts, which are potential water-splitting agents for the production of hydrogen fuel from water and sunlight. Ruibo Zhang (Binghamton University) and Feng Wang (Brookhaven) discussed how XPD tools could be used to monitor changes in the structure and composition of battery materials at their interfaces and in bulk phases.
The XPD will enable quantitative structural studies of polycrystalline samples, experiments that are unmanageable almost everywhere else. Branton Campbell (Brigham Young University) explained that this is important because many samples of interest cannot be grown as single crystals.
Session participants also discussed XPD’s role in the multi-agency Materials Genome Initiative, which aims to halve the current time and cost for transitioning breakthroughs from the laboratory to the marketplace by tightly integrating theoretical predictions, syntheses, and testing of material properties – that is, designing materials with specific properties rather than making “chance” discoveries. XPD will provide valuable insight into some of these structures.
Many additional first experiments were proposed. These include studying nanocatalysts to fuel the water-gas shift reaction in hydrogen fuel cells; measuring the corrosion of zirconium alloys, which are used as cladding materials in nuclear reactors; several proposals in the area of high-pressure studies, which will be a key part of the XPD program; and studies into a possible hydrogen storage material, magnesium borohydride, under real working conditions.
At the CHX session, participants discussed one of the beamline’s key techniques, x-ray photon correlation spectroscopy (XPCS), which will be used to study nanoscale dynamics in a variety of materials. These studies will take place on timescales and length scales not possible before, and the excitement over these capabilities was evident during the presentations and discussions.
Investigations of out-of-equilibrium systems will be of major interest at CHX. During several of the talks, it became evident that CHX will be ideally suited for the study of non-equilibrium “glassy” materials. One of the most important concepts used to describe such systems is that of dynamical heterogeneities, yet x-ray measurements of dynamical heterogeneities are notoriously difficult because the signal-to-noise is often limited by the source brightness. NSLS-II will be uniquely well positioned to enable transformational changes.
Some of the talks addressed the self-assembly of “soft” materials, which is a promising way to achieve new materials with new functions. The CHX beamline will introduce important experimental capabilities to this field, helping researchers to understand the dynamical processes taking place during self-assembly and therefore control those processes. Soft materials are often excellent models for biological systems; the direct study of “bio-” or “bio-inspired” materials is a topic of broad interest for the coherent scattering community, as clearly shown by several talks.
Many talks addressed the study of structural fluctuations at the nanoscale in inorganic materials using high momentum transfer x-ray diffraction. These are fundamentally important measurements that can only be taken by x-rays.
The CSX sessions focused on those branch beamlines’ signature capabilities – the highest coherent flux in the soft x-ray region (CSX-1) and fast switching of the incident x-ray polarization (CSX-2). CSX-1 will allow measurements of electronic textures (inhomogeneities) in strongly correlated electron systems with a resolution better than 50 nanometers by either scanning zone plate imaging or coherent diffraction imaging techniques. One example is measuring stripe domains in high-temperature superconductors using resonant soft x-ray scattering. Attendees also discussed possibilities for XPCS from magnetic systems based on recent work at the Advanced Light Source by Sujoy Roy et al., where information on the dynamics of magnetic domains close to a phase transition can be obtained.
During the CSX-2 session, participants discussed how its unique fast switching capabilities will increase dramatically the sensitivity of x-ray circular magnetic dichroism to measure such materials as dilute magnetic semiconductors. The possibility of a future program to focus on ambient pressure x-ray photoelectron spectroscopy was presented with an emphasis on catalysis science.
Presentations at the SRX session reflected that beamline’s ability to host experiments using several techniques, including x-ray fluorescence imaging, x-ray absorption near-edge spectroscopy, x-ray spectromicroscopy, x-ray tomography, and x-ray microdiffraction. It will offer high-flux and high-resolution modes, which will be useful for a variety of studies. Examples are investigations of nano-inclusions in solar cells, suggested by Steve Heald (Argonne National Laboratory), and platinum nanoparticle catalysts, as discussed by Yuanyuan Li (Yeshiva University).
Tim Glotch (Stony Brook University) described the potential role of SRX in the Solar System Exploration Research Virtual Institute proposal submitted to NASA. This multi-group project would study how materials on asteroids, the Moon, and Mars moons Phobos and Deimos weather bombardment by micrometeorites and solar wind. At SRX, these samples will be studied with a resolution of less than 100 nanometers.
SRX may host research related to shale gas production, such as studies to investigate what materials besides methane, the desired gas, are brought up with the water that is pumped down into drill holes. The nanoscale impact on minerals would be a focus via the study of tiny grains, made possible by the excellent resolution of SRX. This was presented by Jeff Fitts (Princeton University).
The IXS session on October 1 was attended by 12 invited speakers and 43 registered participants. It was organized by IXS personnel Yong Cai and Alessandro Cunsolo (both with Brookhaven) and the chair of the IXS beamline advisory team, Clement Burns (Western Michigan University). IXS’ main features will be a very high-energy resolution (1 meV), excellent momentum resolution (0.1 nanometer1), and sharp tails on the resolution function. The sharp tails allow excellent discrimination between background signals and the excitations under study.
IXS will offer many new opportunities in physics, chemistry, biology, and geology. The session was abuzz about the scientific possibilities, and the talks produced an extensive open discussion.
Tullio Scopigno (Università La Sapienza, Rome), Aleksandr Chumakov (European Synchrotron Radiation Facility) and Keith Nelson (Massachusetts Institute of Technology) discussed opportunities for addressing longstanding scientific questions relating to liquids and disordered materials. Alexei Sokolov (University of Tennessee and Oak Ridge National Laboratory) and IXS’ Cunsolo discussed possible experiments in the area of soft matter and colloidal systems.
Opportunities in protein studies were then discussed by Sow-Hsin Chen (MIT), followed by a talk on biological membranes by Maikel Rheinstädter (McMaster University, Canada). Ho-Kwang Mao (Carnegie Institute of Washington) and Jung-Fu “Afu” Lin (University of Texas, Austin) discussed how IXS might be used to look into outstanding issues in high-pressure physics. The talks concluded with Yuri Shvyd’ko (Argonne National Lab), who reported recent results from a high-resolution spectrometer similar to the instrument being built at NSLS-II. Shvyd’ko also outlined a new approach to achieve higher resolution with better count rates using a spectrographic technique.
2013-4388 INT/EXT | Media & Communications Office