Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 266 for “"X-Ray absorption"”.
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X-Ray Absorption in Layered Crystals
Extended x-ray absorption fine struture (EXAFS) spectra have been obtained for a group of layered transitional-metal dichalcogenide crystals, including the nonstoichiometric compounds Ti(,1+x)Se(,2) and the alloys Zr(,x)Ti(,1-x)Se(,2). Fourier transform analysis of the EXAFS spectra has been …
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X-ray absorption by the intergalactic medium
… galaxy clusters and groups via the so-called "X-ray Forest" the X-ray absorption lines produced by the hot IGM. I gave a semi-analytic calculation of the X-ray forest distribution based on the Press-Schechter formalism. The warm-hot intergalactic medium - the IGM between 10⁵ - 10⁷ K - was …
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Chemistry Of Antiwear Films By X-ray Absorption Spectroscopy
… wear. Among the surface techniques employed, X-ray absorption spectroscopy (including EXAFS and XANES) has been mainly used because of its high resolution, low detection limit and non-destructive characteristics.;This is the first time that P and S L-edge XANES spectroscopy has been used to …
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Computational Studies on Bimetallic Catalysis and X-ray Absorption Spectroscopy
… performed on bimetallic catalysis and on X-ray absorption spectroscopy of insulators. The viability of a bimetallic rhodium and cobalt catalysts for industrially important hydroformylation and aldehyde-water shift catalysis (AWS) is discussed. Density functional theory (DFT) studies were …
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X-ray absorption spectroscopy of actinide speciation in solid solutions
… to a wide range of conditions is required. X-ray absorption spectroscopy (XAS), a nondestructive technique that is ideal for determining the molecular composition of materials in dilute quantities in solution and solid forms, was used to determine the speciation of actinides in various solid …
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Developments in the Theory of X-ray Absorption and Compton Scattering.
X-ray spectroscopy is a widely used technique in experimental and theoretical physics for studying electronic and chemical properties of materials. Theoretical approaches for studying x-ray absorption (XAS) and x-ray photoemision (XPS) properties are described by single particle Green’s function …
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Comparative Analysis and Speciation of Sulfur K, L-edge X-ray Absorption Spectroscopy
… state ranging from -2 to +6, using K-edge X-ray absorption spectroscopy is particularly useful for determining oxidized species. There are, however, limitations on the ability to visually resolve spectra for reduced and mixed sulfur compounds using the K-edge that may be better resolved using …
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OPERANDO X-RAY ABSORPTION SPECTROSCOPY STUDIES OF (PHOTO)ELECTRODE MATERIALS FOR H2 PRODUCTION/CONVERSION
… (SEM), transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis. (2) The electrochemical performance, reaction mechanism, charge transfer kinetics, and overpotential of the synthesized electrodes were rigorously …
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Ruthenium K-edge X-ray absorption spectroscopy studies of ruthenium complexes relevant to olefin metathesis
… have been investigated using Ru K-edge X-ray absorption spectroscopy. The lowest energy feature in the Ru K-edge spectrum has been unambiguously assigned as due to Ru 4d←1s transitions. These electric-dipole-forbidden transitions are extremely sensitive to geometry. For centrosymmetric …
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Modeling Metal Protein Complexes from Experimental Extended X-ray Absorption Fine Structure using Computational Intelligence
Experimental Extended X-ray Absorption Fine Structure (EXAFS) spectra carry information about the chemical structure of metal protein complexes. However, pre- dicting the structure of such complexes from EXAFS spectra is not a simple task. Currently methods such as Monte Carlo optimization or …
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Scanning transmission electron microscopy (STEM) and X-ray absorption spectroscopy (XAS) investigations of catalytic systems
… metal nanoparticles using, predominantly, X-ray absorption spectroscopy (XAS) and scanning transmission electron microscopy (STEM) or spherical aberration-corrected STEM (Cs-STEM). Although the majority of the work focuses on γ-Al2O3 supported nanoparticles because of their industrial …
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Structure of valinomycin-K+ complex and cryptate-k+ complex in solution by extended x-ray absorption fine structure
… study the structure of molecules is Extended X-ray Absorption Fine Structure (EXAFS). EXAFS is small oscillatory signals added on to the smooth x-ray absorption structure curve produced from the excitation of an inner electron out of its bound inner shell into a free electron state. The …
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Defect Production in Alkali Halide Crystals by Monochromatic X and Ultraviolet Radiation (Photoluminescence, X-Ray Absorption, Spectra, Impurity)
… this efficiency was measured in the hard x-ray region at the K-edge of bromine in KBr and in the near ultraviolet part of the spectrum corresponding to the exciton region of the alkali halides. A significant increase in the production efficiency was observed at the K-edge, indicating a new …
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Reactions of Halogenated Ethylenes on the α-Cr₂O₃ (101̅2) Surface
… surface chemistry. Photoemission and near edge x-ray absorption fine structure spectra show that all studied reactants undergo some C-X bond cleavage upon low temperature adsorption forming adsorbed C2 fragments and halogen adatoms. Photoemission for each reaction system shows at least two C1s …
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Structure and Dynamics in Ligand-Protected and Supported Metal Nanoparticles
This dissertation describes the use of x-ray absorption spectroscopy (XAS) and advanced electron microscopy methods to develop fundamental understandings of nanoparticle structure. Analysis of the x-ray absorption spectra provides structural information with 0.001 A precision. Quantitative …
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Understanding the origin of the recovery of superconductivity in halogenated YBCO single crystal : atomic structure study
… this problem, we have performed multiple-edge x-ray absorption fine structure (XAFS) measurements about the Y K, Ba L_3, I L_3, Cu K and Br K-edges at room temperature on brominated (non-brominated) and iodinated (non-iodinated) YBCO single crystals. Our XAFS results at the Br K (brominated) and …
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Soft x-ray near edge spectroscopy of cuprous oxide and silicon-germanium alloys
High resolution soft x-ray absorption near edge structure (XANES) spectra have been obtained for CU20 and for SiGe1-x semiconductor alloys, xas a function of composition x, using the methods of partial electron yield and thin film absorption. The shapes of the near edge features provide a unique …
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