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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 surface complex formed by uranyl oxocations sorbed onto rutile titanium oxide has been probed by X-ray Absorption Spectroscopy, which is part of a work that aims to model the interaction between heavy metal ions and mineral surfaces in aqueous conditions.
Abstract: The surface complex formed by uranyl oxocations sorbed onto rutile titanium oxide has been probed by X-ray Absorption Spectroscopy. These measurements are part of a work that aims to model the interaction between heavy metal ions and mineral surfaces in aqueous conditions. In order to define the orientation and structure of the oxocation complex on the surface, both polycrystalline and monocrystalline (110) and (001) planes of rutile TiO2 have been investigated. Polarized XANES measurements show that the uranyl rod sorbs nearly parallel to the rutile surface, although this ideal configuration must be modulated by the surface topographic defects. Site by site simulation compared to the EXAFS data suggests that two surface oxygen sites are involved: shared edge and shared summit oxygen atoms of the TiO6 octahedron. Both grazing incidence EXAFS on the (110) plane and isotropic EXAFS on polycrystalline TiO2 reveal comparable sorption behavior: on average, the uranyl oxocation bonds to the surface as a bidentate complex with two short oxygen distances at 2.32 A and three larger distances at 2.47 A. Grazing incidence EXAFS on the (001) plane shows an unexpected low signal to noise ratio due to the lower uranium uptake. Data analysis suggests the formation of an outer sphere uranium complex on this plane. The discrepancy between both plane reactivities is still not understood.

72 citations

Journal ArticleDOI
TL;DR: In this article, in situ X-ray absorption spectroscopy experiments during the electrochemical oxidation reaction were performed for both SrFeO2.5 and SrCoO2, respectively.
Abstract: Low temperature oxygen ionic conductors are key materials for the development of the next generation solid oxide fuel cells. In this regard, SrMO2.5 (M = Fe,Co) systems with a Brownmillerite-type structure are able to reversibly intercalate oxygen in an electrochemical reaction at room temperature to reach SrMO3 stoichiometry. To understand and characterize this behavior, at the atomic level, in situ X-ray absorption spectroscopy experiments during the electrochemical oxidation reaction were performed for both SrFeO2.5 and SrCoO2.5 compounds at the Fe and Co K-edge, respectively. The comparative analysis of the two experiments allowed us to emphasize the similarities and differences observed during electrochemical oxidation of the two parent compounds. The data were analyzed both in XANES and EXAFS regions to extract both electronic configuration and local order information. To extract as much information as possible from collected data, the standard linear combination of spectra was complemented by the p...

72 citations

Journal ArticleDOI
TL;DR: In this article, the near edge x-ray absorption fine structure (NEXAFS) spectra of ethylene on Pt(111) at 90 and 300 K have been measured and compared to the spectra calculated using the multiple scattering Xα method for cluster models of adsorbed ethylene and ethylidyne.
Abstract: The near edge x‐ray absorption fine structure (NEXAFS) spectra of ethylene on Pt(111) at 90 and 300 K have been measured and compared to the spectra calculated using the multiple scattering Xα method for cluster models of adsorbed ethylene and ethylidyne. The results indicate that ethylene is adsorbed in the di‐σ configuration (sp3 hybridization) at 90 K, and that the π* orbital retains its identity in this configuration, with no component along the C–C axis. The spectrum obtained at 300 K is attributed to ethylidyne (CCH3) and the calculated spectrum for a cluster consisting of this species bonded symmetrically to three Pt atoms is in good agreement with experiment. The calculations show that the multiple scattering molecular cluster approach is a useful technique for interpreting the NEXAFS spectra of adsorbed molecules.

72 citations

Journal ArticleDOI
TL;DR: Improvements in laser calorimetric or thermal rise techniques are described of which the most important is a means of separating surface and bulk absorption.
Abstract: Laser calorimetric or thermal rise techniques are useful for the determination of very low absorption coefficients in solids. A number of improvements in this technique are described of which the most important is a means of separating surface and bulk absorption. These techniques have been applied to study alkali halides in the ir but are applicable where laser sources of sufficient power are available.

72 citations


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