Aluminum K-XANES spectra in minerals as a source of information on their local atomic structure

For Al containing compounds with different symmetry types of Al environment (from fourfold to 12-fold coordinated Al) it is revealed that Al K-XANES spectra are well reproduced by the XAFS code, based on the method of Hartree-Fock MT-potential generation, considering the photoelectron single-, double- and triple-scattering processes on approximately linear two- and three-atom chains, originated at the absorbing Al atom. The empirical 'selection rules' for choosing these chains are obtained and the origins of features in spectra are interpreted using the SELCOMP code. The proposed EXAFS-like approach for Al K-XANES description is applied also to explain the differences in Al K-XANES spectra, caused by the replacement of Fe atoms by Al atoms in goethite ( alpha -FeOOH).