AN EXAFS STUDY OF REVERSIBLE PHOTOSTRUCTURAL CHANGES IN AS2SE3 GLASS

Reversible photostructural changes in a binary As2Se3 glass have been studied by high-precision in-situ EXAFS. We demonstrate that the coord ination number of selenium species increases reversibly in the photoex cited state while the coordination number for arsenic species remains unchanged, which is attributable to the creation of dynamic Se-Se inte rlayer bonds. Photoexcitation increases disorder near selenium and ars enic species and gives rise to bond breaking which restores the initia l coordination number of both constituents and creates ''wrong'' As-As and Se-Se bonds. (C) 1997 American Institute of Physics.