J. Phys. IV France 7 (1997) C2-199-C2-201
Study of Pre-Edge Structures in the K-Edge XANES/ELNES Spectra of some Transition-Metal Oxides and SulfidesZ.Y. Wu1, 2, G. Ouvrard1 and C.R. Natoli2
1 Institut des Matériaux de Nantes, UMR 110 du CNRS, Laboratoire de Chimie des Solides, 2 rue de la Houssinière, 44072 Nantes cedex 03, France
2 INFN, Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati, Italy
The oxygen, sulfur, and 3d transition metal, Ti and Fe, K-edge XANES/ELNES spectra, with particular references to TiO2 (rutile), TiS2, and α-Fe2O3, have been calculated by using full multiple-scattering (MS) theory and different size clusters. The comparison to experimental data has demonstrated that one would need to take account of higher coordination neighbors, i.e. so called "long-range" effects, in constructing molecular orbitals. The cluster size should be at least two times the cation-anion bond length in the case of anion taken as central atom, and cation-cation plus cationanion bond lengths when cation is taken as center of cluster. Based on this general rule, we are able to reproduce the preedge peaks (including the crystal-field splitting) and obtain excellent agreements with experimental data. The detailed quantitative interpretation of the pre-edge structures of these three compounds is presented.
© EDP Sciences 1997