SULFUR K-EDGE AND L-EDGE XANES AND ELECTRONIC-STRUCTURE OF ZINC, CADMIUM AND MERCURY MONOSULFIDES - A COMPARATIVE-STUDY

S K- and L-edge X-ray absorption near-edge structure (XANES) spectra o f sphalerite (cubic ZnS), wurtzite (hexagonal ZnS), greenockite (hexag onal CdS), metacinnabar (cubic HgS) and cinnabar (trigonal HgS) have b een obtained using synchrotron radiation. The near-edge features of th e S K- and L-edge XANES are qualitatively interpreted based on the MO/ energy band structures of these Zn, Cd and Hg monosulfides. The near-e dge features reflect the density of the states (DOS) of unoccupied S 3 s, 3p and 3d states in the conduction band (CB). From ZnS to CdS and H gS, the S K- and L-edges shift toward lower energy by about 2.3 and 1. 8 eV, respectively, and the energy gap decreases by about 1.9 eV, indi cating that the unoccupied S 3s and 3p states, and the CB minimum move down to lower energy. In transition metal sulfides, the bonding behav iour of Zn 3d10, Cd 4d10 and Hg 5d10 electrons is distinct, and also d iffers significantly from that of Fe3+ 3d and Cu+ 3d electrons, which have a stronger bonding interaction with sulfur. The Fe2+ 3d crystal f ield band in the fundamental gap of (Zn, Fe)S has been confirmed to ha ve little DOS involving S 3s- and 3p-like states. For tetrahedrally co ordinated sphalerite, wurtzite, greenockite and metacinnabar, the post -edge features of the S K- and L-edge XANES are linearly correlated wi th the reciprocal interatomic distances and lattice plane distances. H ence, the S K- and L-edge XANES of Zn, Cd and Hg monsulfides provide i nformation on the local structure and coordination of sulfur atoms. Th e K-edge XANES of different anions in ZnS-structure compounds are qual itatively similar, and may be used as structural fingerprints for stud ying local structures of unknown materials, such as chalcogenides glas ses and metalloproteins.