Polarized X-ray absorption. Evidence of orientational dispersion in hornblende minerals

The first experimental evidence for orientational dispersion of an absorption tensor in the X-ray regime is presented. For two amphibole minerals, edenite and hastingsite, the X-ray absorption tensors were determined at the Fe K edge by means of polarized fluorescence spectroscopy. Analysis of the energy-dependent tensor elements revealed anisotropic anomalous scattering and, in analogy to visible light optics, energy dependence of the respective absorption tensor orientations. Hence, the experiments provide further evidence for the optical model developed earlier describing the polarized near-edge absorption.