S K-EDGE AND L-EDGE XANES AND ELECTRONIC-STRUCTURE OF SOME COPPER SULFIDE MINERALS

The S K- and L-edge x-ray absorption near-edge structures (XANES) of l ow bornite, cubanite, chalcocite, covellite, enargite and tetrahedrite have been measured with synchrotron radiation. The near-edge features are interpreted based on comparison with the S K- ead L-edge spectra of chalcopyrite and a MO/energy band structure model. The XANES spectr a of these sulfides reflect the DOS of unoccupied S s-, p- and d-like states near and above the Fermi level. In tetrahedral Cu-Fe sulfides, the Fe3(+) 3d crystal field band has much more significant DOS of unoc cupied S 3p- and 3s-like states than the Cu+ 3d crystal field band. Fo r Cu sulfides, the Cu+ 3d crystal field band has the higher DOS of S 3 p-and 3s-like states in tetrahedral structure than in structures with the triangular CuS3 cluster. The shifts in both S K- and L-edges corre late approximately linearly with the energy gap.