Natural linear dichroism in pyrite (FeS2): experiments and calculations

Electric quadrupole transitions are revealed through the angular dependence of X-ray absorption spectra in a cubic crytal. Data collection was achieve d at the iron K-edge in pyrite (FeS2) by using the angular moment method de veloped for X-ray Natural Circular Dichoism (XNCD) measurements. The natura l linear dichroism (XNLD) was found to be around 0.5% of the edge jump. Exp erimental results are compared with monelectronic and multilectronic calcul ations. Calculations allow to quantitatively determine the proportion of qu adrupolar transitions in the pre-edge structure and the anisotropy is expla ined in terms of structural and electronic parameters.