D. Cabaret et al., FULL MULTIPLE-SCATTERING CALCULATIONS OF THE X-RAY-ABSORPTION NEAR-EDGE STRUCTURE AT THE MAGNESIUM K-EDGE IN PYROXENE, The American mineralogist, 83(3-4), 1998, pp. 300-304
We present a comparison between XANES experiments and full multiple-sc
attering calculations at the magnesium K-edge for two pyroxenes, diops
ide and enstatite, for which Mg atoms are only in the M1 site and in t
wo distinct sites M1 and M2, respectively. The influence of the number
of octahedral sites per unit cell and of the site distortion on ME K-
edge XANES spectra is investigated. Good agreement between experiment
and calculations is obtained. Full multiple-scattering calculations pe
rmit identification of the contribution of each site. Comparison revea
ls that the Mg K-edge spectra of enstatite and diopside M1 sites have
the same XANES profile. Cluster size analysis shows that most Mg K-edg
e XANES features are related to medium range order, i.e., 6 Angstrom a
round the absorbing atom. We therefore clearly define the Mg K-edge si
gnature of the geometrical arrangement of atoms around each site, M1 a
nd M2.