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Seminar 4/16/2014 - Robert Kolasinski, Sandia National Laboratories: Ion Scattering as a Probe of the Atomic-Scale Behavior of Hydrogen on Surfaces

Apr 16, 2014  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Abstract: Directly detecting the atomic-scale behavior of adsorbed hydrogen is notoriously difficult, and represents a long-standing challenge in surface science. Nevertheless, how hydrogen interacts with metal surfaces is a key problem that affects a variety of technologically important systems, including structural materials for hydrogen energy infrastructure, fuel cells, catalysts, and plasma-facing materials for magnetic fusion energy. To provide insight into some of the materials problems that arise in these applications, we use low energy ion scattering (LEIS) and direct recoil spectroscopy (DRS), unique surface analysis techniques that directly detect adsorbed hydrogen and provide isotopic sensitivity. In our recent work at Sandia, we applied LEIS to examine the atomic-scale behavior of hydrogen on single crystal surfaces in a high-purity vacuum environment. Our basic approach bears many similarities to molecular beam scattering techniques commonly used to study combustion and plasma processes. We use an ion gun to bombard surfaces with He+ and Ne+ at energies < 5 keV, and subsequently detect the scattered and recoiled particles. From this information one can determine the structure and composition of the first few atomic layers of a surface. In this talk, I will provide an overview of the physics that underlies LEIS, along with our recent advances to directly detect adsorbed hydrogen [1]. In addition, I will describe our efforts to more accurately model atomic collisions that occur during scattering [2], a key step needed to extract structural information from LEIS. I will also highlight our recent measurements of the atomic-scale binding configuration of hydrogen to Be and W, two materials of interest as plasma-facing surfaces for magnetic fusion energy.

[1] R. D. Kolasinski, N. C. Bartelt, J. A. Whaley, and T. E. Felter, Phys. Rev. B 85 (2012) 115422.
[2] R. D. Kolasinski, J. A. Whaley, and R. Bastasz, Phys. Rev. B 79 (2009) 075416.

Bio: Robert Kolasinski is a senior member of the technical staff in the Hydrogen and Metallurgical Science Department at Sandia National Laboratories, in Livermore, CA. While at Sandia, Rob’s research efforts have focused on hydrogen interactions with surfaces, low energy ion beam analysis, and plasma-material interactions. Rob received M.S. (2001) and Ph.D. (2007) degrees from the California Institute of Technology in mechanical engineering. While at Caltech, he studied ion-surface interactions in plasma propulsion systems as part of a collaboration with the Advanced Propulsion Group at the NASA Jet Propulsion Laboratory.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 4/23/2014 - Steven Girvin, Yale University: Quantum Measurements and Back-Action (Spooky and Otherwise)

Apr 23, 2014  ·  12:00 p.m. 1:00 a.m.  ·  Bowen Hall Auditorium

Abstract: The topic of measurements and measurement back-action in quantum mechanics was endlessly confusing to the founders of quantum mechanics who were forced to argue in terms of gedanken experiments. Now we must face this confusion because real experiments are happening. This talk will present an introductory tutorial on how real measurements work and how they affect the state of the quantum system under observation. The basic concepts will be illustrated with the Stern-Gerlach experiment and then extended to include dispersive coupling of atoms or qubits to resonant cavities.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 4/30/2014 - Jean Paul Allain, Univ of Illinois, Urbana-Champaign: Plasma-Liquid Surface Interactions in Magnetic Nuclear Fusion

Apr 30, 2014  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Abstract: The plasma-material interface and its impact on performance of magnetically-confined thermonuclear fusion plasma is considered to be one of the key scientific gaps in the realization of nuclear fusion power.  At this interface high particle and heat flux from the fusion plasma can limit the material’s lifetime and reliability and therefore hinder operation of the fusion device.  The power dissipated over the plasma-wetted surfaces can lead to substantial degradation of materials. In particular, when operating in burning plasma, long-pulse regimes the plasma-facing components are exposed to large fluxes of helium compromising candidate materials, which include tungsten, graphite and beryllium.  Both a neutron flux and particle ion flux (e.g. He, D, T) penetrate the plasma-facing components at various spatial scales that modify the intrinsic properties of the materials.  The plasma-material interface is a key region in the device since material can be emitted both atomistically (evaporation, sputtering, etc…) and/or macroscopically (i.e. large clusters during disruptions).   This talk highlights recent attention to the use of liquid metals as candiate plasma-facing component materials.  Particular emphasis is placed on studies focused on particle-liquid surface interaction in laboratory experiments and also work in existing experimental nuclear fusion reactors.  Key knowledge gaps will be outlined as well as future directions for plasma-liquid surface interaction research will be presented.

Bio: Prof. Jean Paul Allain completed his Ph.D. degree from the Department of Nuclear, Plasma and Radiological Engineering at the University of Illinois, Urbana-Champaign.  He received a M.S. degree in Nuclear Engineering from the same institution. Prof. Allain joined Argonne National Laboratory as a staff scientist in 2003 and joined the faculty in the School of Nuclear Engineering at Purdue University in Fall of 2007 with a courtesy appointment with the School of Materials Engineering.  Prof. Allain recently joined the faculty at the University of Illinois at Urbana-Champaign in the Department of Nuclear, Plasma, and Radiological Engineering.  He is an affiliate faculty with the Department of Bioengineering and the Micro and Nanotechnology Lab.  Prof. Allain is the author of over 90 papers in both experimental and computational modeling work in the area of particle-surface interactions.  His research includes developing in-situ surface structure and composition evolution characterization of heterogeneous surfaces under low-energy irradiation promoting structure and function at the nanoscale. Prof. Allain was recipient of numerous awards including the DOE Early Career 2010 Award and the Research Excellence Award in 2011.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 5/7/2014 - Claire E. White, Princeton University: Engineering Sustainable Cements at the Mesoscale

May 7, 2014  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Abstract: Understanding the formation mechanisms and phase stability of amorphous aluminosilicates is extremely important for a range of geological and industrial processes including zeolites, glasses and low-CO2 geopolymer cements. However, due to their disordered nature at the atomic length scale it is difficult to elucidate the exact structural rearrangements occurring during formation. Here, two state-of-the-art theoretical and experimental approaches will be outlined, and their suitability for studying amorphous aluminosilicates will be discussed.

Novel modeling and simulation methods across length scales are emerging in the research community, yet it remains difficult to span length scales without a significant compromise in accuracy. Coarse-grained Monte Carlo simulations used in conjunction with quantum chemical thermodynamic calculations is a relatively new methodology capable of spanning the atomic and nanoscale (toward the mesoscale). Here, it will be applied to modeling (i) silicate speciation (oligomerization) as a function of concentration at high pH, and (ii) the geopolymerization reaction, revealing new structural insight on the formation mechanisms taking place. The advantages and disadvantages of using this multiscale simulation methodology will be outlined and compared with conventional simulation approaches.

Experimental pair distribution function analysis is a powerful tool capable of elucidating the local structural motifs present in amorphous materials. This technique is well-suited for studying the structural arrangements in amorphous aluminosilicates, including glasses and cements. Here, by utilizing pair distribution function analysis it will be shown that the atomic structure of calcium-aluminum-silicate-hydrate gel (found in alkali-activated slag cements) is intrinsically different to calcium-silicate-hydrate gel known to exist in ordinary Portland cement (OPC)-based concrete. This fundamental difference (amorphous versus nanocrystalline) draws into question the suitability of OPC-based approaches (thermodynamic modeling, atomic ordering, phase formation) for studying alkali-activated cement systems.

Bio: Claire White received a B.Eng. in Civil Engineering and a B.S. in Physics from the University of Melbourne, Australia, in 2006. She completed her graduate studies in 2010 at the University of Melbourne in the Geopolymer and Minerals Processing group, supported by an Australian Postgraduate Award from the Australian government. After receiving her Ph.D., she worked as a postdoc at Los Alamos National Laboratory, and was awarded a Director’s Postdoctoral Fellowship to research the atomic structure of low-CO2 alkali-activated cements. In 2012, she was awarded the Outstanding Student Research Prize from the Neutron Scattering Society of America in recognition of her Ph.D. research contributions to neutron sciences. In August, 2013 she joined the faculty at Princeton University as an Assistant Professor in the Department of Civil and Environmental Engineering and the Andlinger Center for Energy and the Environment. Her research group focuses on understanding and optimizing engineering and environmental materials, including low-CO2 cements and amorphous carbonate-based phases. This research spans multiple length and time scales, utilizing advanced synchrotron and neutron-based experimental techniques, and simulation methodologies.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Class Day 6/2/2014 - Materials Science & Engineering Graduation and Reception

Jun 2, 2014  ·  1:30 p.m. 2:00 p.m.  ·  Bowen Hall Auditorium

Congratulations, Class of 2014!

Please come and celebrate the MSE graduating seniors on Monday, June 2, 2014 at 1:30 p.m. in the Bowen Hall Auditorium. Light refreshments will be available before and after the ceremony in the Bowen Hall Atrium.