? x-ray fluorescence spectra of the ? - ? chalcogenide system

The sulphur 3p valence states of 0953-8984/8/43/033/img14, 0953-8984/8/43/033/img15, 0953-8984/8/43/033/img16, 0953-8984/8/43/033/img17, 0953-8984/8/43/033/img18, and 0953-8984/8/43/033/img19 of the 0953-8984/8/43/033/img19 - 0953-8984/8/43/033/img14 system have been investigated by means of the 0953-8984/8/43/033/img22 (0953-8984/8/43/033/img23) x-ray emission band. 0953-8984/8/43/033/img17 and 0953-8984/8/43/033/img18 were also studied in the glassy phase. Synchrotron-radiation-induced fluorescence was used. The spectra are discussed in terms of bonding between the sulphur atoms and their nearest neighbours with the help of tight-binding calculations. We observe significant differences among the S 3p states of all these materials, including between the crystalline and glassy phase of 0953-8984/8/43/033/img17. The variations in the 0953-8984/8/43/033/img22 bandwidth and shape clearly reflect the sensitivity of the S 3p states to the local environment and indicate that the valence densities of states are mainly influenced by local order.