AN XAS STUDY OF THE SEMI-CONDUCTING SULFIDES M2S3 (M=AS, SB, BI)

XANES has been used to probe the low-lying vacant slates in the Period 15 sulfide semi-conductors M2S3 (M = As, Sb, Ui). The As K-and L-3-, Sb K- and L-3-, and Bi L-3- and L-1-edges are related to the S K-edge XANES in terms of bands of mixed orbital character. In the K-edge spec tra transitions from the Is state to slates of some p character can be seen in the region between 5 eV before the edge and 15 eV alter it. T he S spectra are alike showing the similar nature of the electronic st ructure of these compounds. The white line intensity decreases down th e period showing tile density of empty S 2p stales al the Fermi level is also decreasing. The Period 15 spectra are related to theoretical b and structure calculations for As2S3.