A5075678838- X-ray Spectroscopy and Fluorescence Analysis
- Semiconductor materials and devices
- Electron and X-Ray Spectroscopy Techniques
- Advanced X-ray Imaging Techniques
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Integrated Circuits and Semiconductor Failure Analysis
- Phase-change materials and chalcogenides
- Radiation Effects in Electronics
- Physics of Superconductivity and Magnetism
- Catalytic Processes in Materials Science
- Intermetallics and Advanced Alloy Properties
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Chalcogenide Semiconductor Thin Films
- Magnetic properties of thin films
- Ion-surface interactions and analysis
- Radioactive element chemistry and processing
- GaN-based semiconductor devices and materials
- Geochemistry and Geologic Mapping
- Semiconductor materials and interfaces
- Advancements in Semiconductor Devices and Circuit Design
- Advanced Memory and Neural Computing
- Nonlinear Optical Materials Studies
- ZnO doping and properties
Argonne National Laboratory
2012-2021
Advanced Photon Source
2018
Northern Illinois University
1986-2010
University of Washington
1995-2005
PNC Financial Services (United States)
2003
University of Connecticut
1989-2000
Seattle University
1998
Battelle
1997
Pacific Northwest National Laboratory
1995
Supercon (United States)
1990
Collaborative Access Team (PNC-CAT) is constructing bending magnet and insertion device (ID) beamlines at the Advanced Photon Source.Both will be heavily used for XAFS micro-XAFS experiments.This paper summarises their capabilities, initial operational experience with ID line.The beamline based on APS undulator A, has been running in an commissioning configuration since May 1997.Currently monochromator energies can scanned synchrony EXAFS measurements, we have obtained focused beams as small...
Facilitated by superior mesoporous structure and rich functional groups, sulfonated carbon fiber with optimized Brønsted Lewis acidity delivers a high yield of glucose from cellulose hydrolysis in water.
The formation of substitutional alloys has been restricted to elements with similar atomic radii and electronegativity. Using high-pressure at 298 K, we synthesized a face-centered cubic disordered alloy highly dissimilar (large Ce small Al atoms) by compressing the Ce(3)Al intermetallic compound >15 GPa or metallic glass >25 GPa. Synchrotron X-ray diffraction, L(3)-edge absorption spectroscopy, ab initio calculations revealed that pressure-induced Kondo volume collapse 4f electron...
Abstract Inverse photoconductivity (IPC) is a unique photoresponse behavior that exists in few photoconductors which electrical conductivity decreases with irradiation, and has great potential applications the development of photonic devices nonvolatile memories low power consumption. However, it still challenging to design achieve IPC most materials interest. In this study, pressure‐driven investigated n‐type WO 3 nanocuboids functionalized p‐type CuO nanoparticles under visible...
We have discovered that the apical oxygen with a 2.35-\AA{} La-O bond length is removed when La substituted by Sr in polycrystalline ${\mathrm{La}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{CuO}}_{4}$ under normal preparation conditions. This can be partially filled annealing. It reasoned defect trapped at an interstitial site near atom. present evidence this intrinsic to doping, independent of processing propose serves as mechanism for hole doping similar...
Thiosulfate and ammonia mixtures may be more environmentally benign alternatives to cyanide for leaching Au from ores. In this method, the Cu(I)/Cu(II) couple acts as a redox mediator aiding in oxidative dissolution of metallic Au. Information about speciation Cu(I) Cu(II) these lixiviant solutions is paramount optimization gold ore processing conditions. With mind, we have carried out XANES, EXAFS UV-Vis spectroscopic studies mixed thiosulfate-chloride ammonia-chloride solutions. solutions,...
Using the x-ray diffraction and absorption fine structure techniques, we have probed $\mathrm{Ti}$, $\mathrm{Ta}$, $\mathrm{Sc}$ local environments in solid solution system $(1\ensuremath{-}x{)\mathrm{Pb}(\mathrm{Sc},\mathrm{Ta})\mathrm{O}}_{3}\text{\ensuremath{-}}x{\mathrm{PbTiO}}_{3}$. This is known to display a variety of ferroelectric behaviors ranging from variable order-disorder, relaxor, mixed phase region, then finally normal ferroelectric, as value $x$ increased. We find, agreement...
Phase-change materials based on Ge-Sb-Te alloys are widely used in industrial applications such as nonvolatile memories, but reaction pathways for crystalline-to-amorphous phase-change picosecond timescales remain unknown. Femtosecond laser excitation and an ultrashort x-ray probe is to show the temporal separation of electronic thermal effects a long-lived ($>$100 ps) transient metastable state Ge$_{2}$Sb$_{2}$Te$_{5}$ with muted interatomic interaction induced by weakening resonant...
Nanoscale CeO2 (nanoceria) is a prototypical system that presents d0 ferromagnetism. Using combination of x-ray absorption spectroscopy, magnetic circular dichroism and modelling, we show nanostructure, defects disorder, non-stoichiometry create magnetically polarized Ce 4f O 2p hybridized states captured by the vacancy orbitals (Vorb) are vital to Further, demonstrate foreign ions (Fe Co) enhance moment at sites while number Vorb unchanged, pointing clearly mechanism orbital hybridization...
The paradigm of "detection-before-destruction" was tested for a metalloprotein complex exposed at room temperature to the high x-ray flux typical third generation synchrotron sources. Following progression induced damage by Mn Kβ emission spectroscopy, we demonstrated feasibility collecting data on electronic structure native Photosystem II, trans-membrane containing Mn(4)Ca cluster. determined non-damaging observation timeframe (about 100 milliseconds using continuous monochromatic beam,...
The Pacific Northwest Consortium-Collaborative Access Team (PNC-CAT) has begun operating an insertion device beamline at the Advanced Photon Source. been extensively used for XAFS studies. This paper summarizes its capabilities, and our initial operational experience. is based on APS undulator A, incorporates full scanning. monochromator liquid nitrogen cooled both Si(111) Si(311) crystals in a side-by-side configuration. Crystal changes only take few minutes. cover energy range from 3-50...
We report an experimental study of the transients generated by pulsed x-rays, heavy ions, and different laser wavelengths in a Si p-i-n photodiode. compare charge collected all excitation methods to determine equivalent LET for x-rays relative ions. Our comparisons show that from synchrotron sources can generate large range similar those excited pulses ion strikes. also look at how pulse width changes methods. with is greater than expected as x-ray photon energy increases. Combined their...
This paper identifies the failure modes of a commercial 130-nm ferroelectric random access memory. The devices were irradiated with heavy-ion and pulsed focused X-ray beams. Various are observed, which generate characteristic error patterns, affecting isolated bits, words, groups pages, sometimes entire regions memory array. underlying mechanisms discussed.
A focused pulsed X-ray beam is used to determine how the redistribution of electric field by gate-connected plate affects single-event transient (SET) susceptibility an AlGaN/GaN Schottky-gate HEMT on SiC. SETs generated scanning across depend strongly presence plate, radiation strike location, bias conditions, and photon energy. For particular we tested, reduces electric-field strength near edge gate a factor approximately 2, which results in faster decaying transients less collected charge.