Abstract
The method for quantitative determination of interatomic distances and coordination numbers (CN) in minerals and amorphous compounds by their x-ray absorption near edge structure (XANES) is proposed. The generation of the method and the proof of its main points are based on the revealed theoretical description of XANES for crystalline compounds and minerals as a sum of different photoelectron scattering processes on two- and approximately linear three-atoms chains, originated at the absorbing atom. The method consists of the Fourier filtration (FF) of the experimental XANES within the short range of photoelectron’s wave numbers and the following fitting, with three varied parameters, of the first shell term extracted by the FF procedure. The accuracy of the obtained local structural parameters is illustrated for the reference crystalline minerals, which are used also to simulate the XANES formation in glasses. The application of the method to Mg XANES in diopside-glass and its crystalline equivalent, Diopside, permits one to determine the Mg-O distance and CN for the first oxygen shell around the Mg atom and to reveal the change of these parameters between the glass and the crystal with similar chemical composition.
- Received 20 April 2001
DOI:https://doi.org/10.1103/PhysRevB.65.024105
©2001 American Physical Society