Proceedings of the 9th International Conference on X-Ray Absorption Fine Structure

J. Phys. IV France 7 (1997) C2-503-C2-504
DOI: 10.1051/jp4/1997070

Comparison of XAS Spectra at the Al K-Edge in Garnets to Multiple-Scattering Calculations

Z.Y. Wu^{1, 2}, A. Marcelli², A. Mottana³, G. Giuli⁴ and E. Paris<sup>4

1</sup>  Institut des Matériaux de Nantes, UMR 110 du CNRS, Laboratoire de Chimie des Solides, 2 rue de la Eoussinière, 44072 Nantes cedex 03, France
²  INFN, Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati, Italy
³  Dipartimento di Scienze Geologiche, Terza Università di Roma, Via Ostiense 169, 00154 Roma, Italy
⁴  Dipartimento di Scienze della Terra, Università di Camerino, 62032 Camerino, Italy

Abstract
High-resolution x-ray absorption near-edge structures at Al K-edge were collected on a series of garnets, pyrope (Mg₃Al₂Si₃O₁₂), almandtae (Fe₃Al₂Si₃O₁₂), spessartine (Mn₃Al₂Si₃O₁₂), and grossular (Ca₃Al₂Si₃O₁₂), using a YB66 crystal monochromator. Full multiple scattering (MS) calculations by using cluster models and different exchangecorrelation potentials were compared with experimental data. An overall good agreement was obtained in the energy range up to 60 eV above the threshold and a clear evidence on the effect of atoms located far away from the first-coordination shell around the photoabsorber was obtained. Moreover the pre-edge feature can be explained in terms of the empty "d" bands of next nearest neighbors.

© EDP Sciences 1997