A5023631463- Electron and X-Ray Spectroscopy Techniques
- Radioactive element chemistry and processing
- X-ray Spectroscopy and Fluorescence Analysis
- X-ray Diffraction in Crystallography
- Nuclear Physics and Applications
- Crystallization and Solubility Studies
- Nuclear Materials and Properties
- Rare-earth and actinide compounds
- Advancements in Battery Materials
- Advanced X-ray Imaging Techniques
- Polyoxometalates: Synthesis and Applications
- Advanced Battery Technologies Research
- Advanced Chemical Physics Studies
- Electrocatalysts for Energy Conversion
- Machine Learning in Materials Science
- Lanthanide and Transition Metal Complexes
- Nuclear reactor physics and engineering
- Magnetism in coordination complexes
- Advanced X-ray and CT Imaging
- Nanocluster Synthesis and Applications
- Advanced Battery Materials and Technologies
- Advanced Nanomaterials in Catalysis
- Advanced battery technologies research
- Vanadium and Halogenation Chemistry
- Iron-based superconductors research
Lawrence Berkeley National Laboratory
2021-2025
Lawrence Livermore National Laboratory
2022
Los Alamos National Laboratory
2018-2021
University of Washington
2016-2021
Berkeley College
2021
Seattle University
2018
Evaluating the nature of chemical bonding for actinide elements represents one most important and long-standing problems in science. We directly address this challenge contribute a Cl K-edge X-ray absorption spectroscopy relativistic density functional theory study that quantitatively evaluates An–Cl covalency AnCl62– (AnIV = Th, U, Np, Pu). The results showed significant mixing between 3p- AnIV 5f- 6d-orbitals (t1u*/t2u* t2g*/eg*), with showing more pronounced covalent than 5f-orbitals....
X-ray absorption fine structure (XAFS) and x-ray emission spectroscopy (XES) are advanced spectroscopies that impact a wide range of disciplines. However, unlike the majority other spectroscopic methods, XAFS XES accompanied by an unusual access model, wherein dominant use technique is for premier research studies at world-class facilities, i.e., synchrotron light sources. In this paper, we report design performance improved spectrometer based on general conceptual Seidler et al. [Rev. Sci....
Cm<sup>III,</sup>Am<sup>III</sup>, and Ac<sup>III</sup>have been characterized by solution L<sub>3</sub>-edge X-ray absorption spectroscopy as a function of nitric acid concentration. This enabled the first experimental determination Cm Ac nitrate distances.
Abstract Developing efficient, economical, and stable catalysts for the oxygen evolution reaction is pivotal producing large‐scale green hydrogen in future. Herein, a vanadium‐doped nickel‐iron oxide supported on nickel foam (V‐NiFe 2 O 4 /NF) introduced, synthesized via facile hydrothermal method as highly efficient electrocatalyst water electrolysis. X‐ray photoelectron absorption spectroscopies reveal synergistic interaction between vanadium dopant nickel/iron host material, which tunes...
X-ray emission spectroscopy is emerging as an important complement to x-ray absorption fine structure spectroscopy, providing a characterization of the occupied electronic density states local species interest. Here, we present details design and performance compact spectrometer that uses dispersive refocusing Rowland (DRR) circle geometry achieve excellent for 2-2.5 keV range, i.e., especially K-edge from sulfur phosphorous. The DRR approach allows high energy resolution even unfocused...
We have recently demonstrated a very favorable, inexpensive modernization of lab-based x-ray absorption fine structure (XAFS) and high-resolution emission spectroscopy (XES) using only commercially-available optics tube sources. Here, we survey several proven instrument designs that can be readily implemented in any laboratory setting to achieve synchrotron-quality XAFS XES for many systems the 5 keV 10 energy range. These approaches are based on our immediate experience with development of:...
Li-ion battery (LIB) research has continuing importance for the entire range of applications from consumer products to vehicle electrification and grid stabilization. In many cases, standard electrochemical methods only provide an overall voltage or specific capacity, giving inadequate description parallel redox processes chemical gradients at particle pack level. X-ray absorption fine structure (XAFS) is frequently used augment bulk data, as it provides element-specific changes in oxidation...
Recently developed instrumentation at the University of Washington has allowed for nonresonant x-ray emission spectra (XES) to be measured in a laboratory-setting with an inexpensive, easily operated system. We present critical evaluation this equipment by means Kβ and valence-level XES measurements several Co compounds. find peak count rates ∼5000/s concentrated samples robust relative energy scale reproducibility 25 meV or better. furthermore excellent agreement synchrotron only modest...
5f covalency in [U(C7H7)2]- was probed with carbon K-edge X-ray absorption spectroscopy (XAS) and electronic structure theory. The results revealed U orbital participation δ-bonding both the ground- core-excited states; additional ϕ-mixing is observed states. Comparisons U(C8H8)2 show greater δ-covalency for [U(C7H7)2]-.
There are more than 100 beamlines or endstations worldwide that frequently support X-ray absorption fine-structure (XAFS) measurements, thus providing critical enabling capability for research across numerous scientific disciplines. However, the absence of a supporting tier readily accessible, lower-performing options has caused systemic inefficiencies, resulting in high oversubscription and omission many scientifically socially valuable XAFS applications incompatible with synchrotron...
An investigation of the structural, thermodynamic, and electronic transport properties isoelectronic chemical substitution series $\mathrm{Ce}{({\mathrm{Pd}}_{1\ensuremath{-}x}{\mathrm{Ni}}_{x})}_{2}{\mathrm{P}}_{2}$ is reported, where a possible ferromagnetic quantum critical point uncovered in temperature-concentration ($T\text{\ensuremath{-}}x$) phase diagram. This behavior results from simultaneous contraction unit cell volume, which tunes relative strengths Kondo...
We demonstrate that vacuum forming of 10-cm diameter silicon wafers various crystallographic orientations under an x-ray permeable, flexible window can easily generate spherically bent crystal analyzers and toroidally with ∼1-eV energy resolution a 1-m major radius curvature. In applications at synchrotron light sources, free electron lasers, laboratory spectrometers, these characteristics are generally sufficient for many absorption fine structure (XAFS), emission spectroscopy (XES),...
A cerium-oxo nanocluster capped by chloride ligands, [CeIV38-nCeIIInO56-(n+1)(OH)n+1Cl51(H2O)11]10- (n = 1-24), has been isolated from acidic solutions using potassium counterions. The crystal structure was elucidated single X-ray diffraction. At the center of cluster is a {Ce14} core that exhibits same fluorite-type as bulk CeO2, with eight-coordinate Ce sites bridged tetrahedral oxo anions. further surrounded peripheral shell six tetranuclear {Ce4} subunits are located on each faces to...
X-ray absorption spectroscopy (XAS) beamlines worldwide are steadily increasing their emphasis on full photon-in/photon-out spectroscopies, such as resonant inelastic scattering (RIXS), emission (RXES) and high energy resolution fluorescence detection XAS (HERFD-XAS). In cases, each beamline must match the choice of spectrometer to scientific mission its users. Previous work has recently reported a miniature tender using dispersive Rowland refocusing (DRR) geometry that functions with even...
Volatile thorium amidates can be converted to ThO<sub>2</sub> in the absence of an external oxygen source, and thermal properties these precursors readily tuned by modifying ligand substituents.
The oxidation of uranium dioxide is a complicated process, depending on factors including humidity, temperature, and microstructure. To further determine the characteristics this UO2 particles were allowed to age agglomerate under 98% relative humidity at room temperature for 378 days. A focused ion beam (FIB) section agglomeration was then measured O K-edge, U N5-edge, C K-edge using scanning transmission x-ray microscope (STXM) Advanced Light Source. N5-edge absorption measurements...
A holder has been developed that enables electron yield-detected soft X-ray spectroscopy of fully contained samples at low temperature. Crucially, this design uses elements the sample containment to collect ejected electrons, removing need expose directly vacuum environment spectrometer. The is modular and should be adaptable a number different endstation configurations, enabling air-sensitive, radioactive vacuum-sensitive (biological) samples.
Traditional models of lanthanide electronic structure suggest that bonding is predominantly ionic, and covalent orbital mixing not an important factor in determining magnetic properties. Here, 4f its impact on the susceptibility Cp'3Eu (Cp' = C5H4SiMe3) was analyzed experimentally using magnetometry X-ray absorption spectroscopy (XAS) methods at C K-, Eu M5,4-, L3-edges. Pre-edge features experimental TDDFT-calculated K-edge XAS spectra provided unequivocal evidence 2p π-antibonding a'...
Soft X-ray spectromicroscopy at the O K -edge, U N 4,5 -edges and Ce M has been performed on focused ion beam sections of spent nuclear fuel for first time, yielding chemical information sub-micrometer scale. To analyze these data, a modification to non-negative matrix factorization (NMF) was developed, in which data are no longer required be non-negative, but non-negativity spectral components fit coefficients is largely preserved. The modified NMF method utilized -edge distinguish between...
Abstract A number of technologies would benefit from developing inorganic compounds and materials with specific electronic magnetic exchange properties. Unfortunately, designing these properties is difficult because metal⋅⋅⋅metal coupling schemes are hard to predict control. Fully characterizing communication between metals in existing that exhibit interesting could provide valuable insight advance those predictive capabilities. One such class molecules the series Lindqvist...
We demonstrate that vacuum forming of 10-cm diameter silicon wafers various crystallographic orientations under an x-ray permeable, flexible window can easily generate spherically bent crystal analyzers (SBCA) and toroidally (TBCA) with ~1-eV energy resolution a 1-m major radius curvature. In applications at synchrotron light sources, free electron lasers, laboratory spectrometers these characteristics are generally sufficient for many absorption fine structure (XAFS), emission spectroscopy...