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Extended X-ray absorption fine structure

About: Extended X-ray absorption fine structure is a research topic. Over the lifetime, 10452 publications have been published within this topic receiving 276744 citations.


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TL;DR: In this article, the local atomic and electronic structures of two related systematic sets of ternary uranium oxides, NaUO3-KUO-3-RbUOO3 and BaUO 3-Ba2U2O7-BaUO4, were investigated by measuring the X-ray absorption near edge structure (XANES) and compared with calculations based on a self-consistent real space full multiple scattering analysis.

72 citations

Journal ArticleDOI
TL;DR: In this article, the valence and local symmetry of iron in framework-substituted FeZSM-5 with a high Fe dilution (Si/Fe = 360) was studied by means of Kβ-detected X-ray absorption spectroscopy.
Abstract: The valence and local symmetry of iron in framework-substituted FeZSM-5 with a high Fe dilution (Si/Fe = 360) was studied by means of Kβ-detected X-ray absorption spectroscopy. This technique combines high-resolution (ΔE ∼1 eV) fluorescence detection of the 3p to 1s (Kβ) transition with the X-ray absorption near-edge structure (XANES) at the Fe K-edge. An absorption-like spectrum is recorded by detecting the Kβ fluorescence intensity as a function of the incident energy that is scanned through the K absorption edge. Kβ-detected XANES spectra allow for a more precise separation of the weak K pre-edge structure from the main edge as compared to conventional absorption spectroscopy. Subsequent analysis and interpretation of the pre-edge spectral features therefore is more accurate. The pre-edge is sensitive to changes in the local coordination and oxidation state of Fe. Using this technique we were able to quantitatively determine the degree of iron extraction out of a zeolite framework upon steaming. With t...

72 citations

Journal ArticleDOI
TL;DR: In this paper, a pure, stoichiometric, hydrogen-free, and crystalline phosphorus nitride P3N5 has been obtained for the first time by reaction of (PNCl2)3 and NH4Cl between 770 and 1050 K.
Abstract: Pure, stoichiometric, hydrogen-free, and crystalline phosphorus nitride P3N5 has been obtained for the first time by reaction of (PNCl2)3 and NH4Cl between 770 and 1050 K. The compound has been characterized by elemental analyses, 31P and 15N MAS NMR, EXAFS, IR spectroscopy, X-ray powder diffraction, and electron microscopy. In the solid a three-dimensional cross-linked network structure of corner sharing PN4 tetrahedra has been identified with 2/5 of the nitrogen atoms bonded to three P atoms and 3/5 of the nitrogen atoms bonded to two P atoms. By electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM) two distinguishable modifications α-P3N5 and β-P3N5 have been identified which differentiate only by the stacking order of identical sheets similar to the polytypes of SiC.

72 citations

Journal ArticleDOI
TL;DR: It was found that the Cu(I) complex formed from the reaction of CuI with β-diketone nucleophile was liable under the cross-coupling conditions, which is usually considered as active catalytic species.
Abstract: Insights toward the Cu-catalyzed C–C coupling reaction were investigated through operando IR and in situ X-ray absorption near-edge structure/extended X-ray absorption fine structure. It was found that the Cu(I) complex formed from the reaction of CuI with β-diketone nucleophile was liable under the cross-coupling conditions, which is usually considered as active catalytic species. This labile Cu(I) complex could rapidly disproportionate to the spectator Cu(II) and Cu(0) species under the reaction conditions, which was an off-cycle process. In this copper-catalyzed C–C coupling reaction, β-diketone might act both as the substrate and the ligand.

72 citations

Journal ArticleDOI
TL;DR: In this article, the authors determined the local atomic structure of MgO epilayers on Ag(001) by means of polarization-dependent x-ray absorption spectroscopy measurements at the Mg and O $K$ edges.
Abstract: We determined the local atomic structure of MgO epilayers on Ag(001) by means of polarization-dependent x-ray absorption spectroscopy measurements at the Mg and O $K$ edges. A quantitative analysis of the data in the extended energy range has been performed using multiple scattering simulations. We found that, even in the ultrathin limit, the local structure of the films is rocksalt and we obtained a quantitative evaluation of the average in-plane and out-of-plane film strain at the different thicknesses investigated. An in-plane compressive strain, due to lattice mismatch with the Ag substrate, is clearly present for the 3 ML film. The out-of-plane lattice constant is found to be expanded, in agreement with the expected behavior for a tetragonal distortion of the unit cell. This growth-induced strain is gradually released with increasing thickness and it is almost completely relaxed at 20 ML. Any significant intermixing with the Ag substrate can be ruled out. An expansion of the interplanar distance at the MgO-Ag interface is detected and its sign and magnitude are found to be in agreement with recent ab initio simulations. This work provides previously unavailable input for modeling the physical properties of the system and supports the hypothesis that the different electronic properties of MgO films on Ag(001) are not related to structural or compositional differences at the ultrathin limit.

72 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023110
2022264
2021156
2020164
2019164
2018151