Energy Dependence of the ATS Reflections of Iron Pyrite, FeS_<b>2</b>, Near the Fe K-Absorption Edge

Abstract

The “forbidden reflection” intensity excited due to the ATS (anisotropy of tensor of susceptibility) in a FeS 2 (pyrite) crystal was measured for X-ray energy near the Fe K-absorption edge from 15 eV below the edge to 65 eV above the edge. In the region above the edge, the ATS intensities for (001), (003) and (011) reflections showed essentially the same energy dependence, two sharp peaks and one broad peak. But below the edge, the energy spectra of the ATS intensity depend on the reflection plane. The azimuthal angle dependence of the intensity cannot be explained by the calculation based on only the dipole transition. Therefore, the scattering is affected by quadrupole transition.