Short- and intermediate-range atomic structure of glassy and liquid As2Se3- An anomalous X-ray scattering study

An anomalous X-ray scattering experiment has been performed for glassy (g-) and liquid (l-) As2Se3 in order to clarify the role of each constituent fo r the short- and intermediate-range order (SRO and IRO). The differential s tructure factors Delta(i)S(Q) close to the As and Se K edges have been obta ined from a detailed analysis. The first nearest-neighbour distances around both As and Se are about 2.4 Angstrom for both g- and l-As2Se3, which woul d support the SRO model that g- and l-As2Se3 have an SRO similar to the cor responding crystal. The pre-peak in S(Q) for g- and l -As2Se3, is dominated by a partial structure factor S-AsAs(Q), which reveals the existence of th e As-As IRO with a correlation length of about 5.2 Angstrom.