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Title:Photoexcitation processes in atoms
Authors:ID Kodre, Alojz, Uni-Lj (Author)
ID Arčon, Iztok, UNG (Author)
ID Padežnik Gomilšek, Jana, Uni-MB (Author)
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Language:English
Work type:Not categorized
Typology:1.16 - Independent Scientific Component Part or a Chapter in a Monograph
Organization:UNG - University of Nova Gorica
Abstract:Photoelectric absorption is characterized by a smooth power-law decrease of the cross section with photon energy. Absorption edges reveal rich structure, which continues into the high-energy side. The quasiperiodic signal, superposed onto the smooth basis, due to scattering of the photoelectron on the neighbours of the target atom provides the basis for the structural (XAFS) analysis of the material. Irregular tiny resonances and edges that appear over the same general range as XAFS are recognized as intra-atomic effects: multielectron excitations (MEE) owing to correlated motion in the electronic cloud. The systematic study of MEE began on noble gases and metallic vapours, both of which are gases of free atoms. With some extremely strong MEE, mostly coexcitations of the subvalence d and f electrons, the structural XAFS analysis may be compromised; hence, there is a need to independently determine the MEE signal, the atomic absorption background (AAB) for the analyzed element, and remove it prior to analysis. In view of the scarcity of elements which can practically be prepared in a free-atom gas state, several approaches to approximate the AAB have been developed: analysis of disordered compounds, where the weak and simple XAFS signal can be modelled and removed, and correlation analysis of the absorption spectra of several independent samples, where the AAB is extracted in an iterative procedure.
Keywords:photoexcitation, XAFS, multielectron excitations, atomic absorption background
Year of publishing:2021
Number of pages:5
Numbering:1, 1
PID:20.500.12556/RUNG-7083 New window
COBISS.SI-ID:89611267 New window
DOI:https://doi.org/10.1107/S1574870720003511 New window
NUK URN:URN:SI:UNG:REP:BDYIG1GF
Publication date in RUNG:15.12.2021
Views:2802
Downloads:0
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KODRE, Alojz, ARČON, Iztok and PADEŽNIK GOMILŠEK, Jana, 2021, Photoexcitation processes in atoms. In : International tables for crystallography [online]. Bognor Regis. Vol. 1, no. 1. [Accessed 7 April 2025]. Retrieved from: https://repozitorij.ung.si/IzpisGradiva.php?lang=eng&id=7083
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Record is a part of a monograph

Title:International tables for crystallography : X-ray absorption spectroscopy and related techniques
Editors:C. T. Chantler
Place of publishing:Bognor Regis
Publisher:Wiley
Year of publishing:2020
ISBN:978-1-119-43394-1
COBISS.SI-ID:89610755 New window
Collection title:International tables for crystallography
Collection ISSN:1574-8707

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