X-RAY-ABSORPTION NEAR-EDGE SPECTRA OF TRANSITION-METAL DISULFIDES FES2 (PYRITE AND MARCASITE), COS2, NIS(2) AND CUS2, AND THEIR ISOMORPHS FEASS AND COASS

Metal K- and L(3)-, sulfur K- and arsenic K- and L(3)-edge X-ray absorption near-edge spectra of a series of metal disulfides, FeS2 (both pyrite and marcasite), CoS2, NiS2, and CuS2 and their isomorphs, FeAsS and CoAsS, are presented. The features in this region of these spectra are interpreted using band structure and molecular orbital calculations in terms of the transitions from the Is or 2p(3/2) state to unoccupied states. The 3d transition metal L(3)-edge spectra of these materials show dependence on the degree of multiplet splitting in the final state, and thus offer less information on the electronic ground state. There are substantial differences in the spectra of the isostructural materials, whereas the spectra of the isotopes pyrite and marcasite show several similarities, illustrating the dependence of near-edge region on electronic structure.