J. Phys. IV France 7 (1997) C2-503-C2-504
Comparison of XAS Spectra at the Al K-Edge in Garnets to Multiple-Scattering CalculationsZ.Y. Wu1, 2, A. Marcelli2, A. Mottana3, G. Giuli4 and E. Paris4
1 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
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