Premium
Origin of the chemical shift in X‐ray absorption near‐edge spectroscopy at the Mn K ‐edge in manganese oxide compounds
Author(s) -
de Vries A. H.,
Hozoi L.,
Broer R.
Publication year - 2002
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.10370
Subject(s) - manganese , x ray photoelectron spectroscopy , chemistry , chemical shift , cluster (spacecraft) , absorption spectroscopy , ionization , ion , k edge , oxide , spectral line , absorption edge , absorption (acoustics) , chemical state , spectroscopy , ionization energy , transition metal , atomic physics , materials science , condensed matter physics , nuclear magnetic resonance , physics , band gap , computer science , composite material , biochemistry , quantum mechanics , programming language , astronomy , catalysis , organic chemistry
The absorption edge in Mn K ‐edge X‐ray absorption spectra of manganese oxide compounds shows a shift of several electronvolts in going from MnO through LaMnO 3 to CaMnO 3 . On the other hand, in X‐ray photoelectron spectra much smaller shifts are observed. To identify the mechanisms that cause the observed chemical shifts, 1 s ionization as well as 1 s → “4 p ” transition energies have been determined by electronic structure calculations on embedded Mn ions and embedded MnO 6 clusters. Systematic variation of the cluster geometry and the cluster embedding showed that the chemical shifts are predominantly determined by two effects: the changes in the Mn 3 d occupation and the changes in the Madelung potential. The large chemical shift in the 1 s → 4 p transition energies between different materials occurs because the two effects do not compensate each other. The chemical shifts obtained for the embedded MnO 6 clusters agree reasonably with the experimental shifts. The small sensitivity to the material observed for the Mn 1 s ionization energies is explained by the near cancellation of the effects of the Madelung potential and the 3 d occupation of the Mn ion. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003