A. Kovalskiy, H. Jain, A. Miller, R. Golovchak and O. Shpotyuk.
The journal of physical chemistry B, vol. 110, 2006, p. 22930-22934.
The structural origin of reversible γ-induced effects in vitreous Ge23.5Sb11.8S64.7 has been investigated by high-resolution X-ray photoelectron spectroscopy (XPS). The changes in valence band spectrum from γ-irradiation suggest a decrease of sulfur lone pair electron concentration accompanied by changes in bonding states of S and Ge. The appearance of additional doublets in the core-level XPS spectra of Ge, Sb, and S atoms for γ-irradiated sample is described by the formation of over- and under-coordinated charged defect pairs (Ge3–-S3+) as a result of radiation treatment. The results verify the switching of Ge-S covalent bonds into S-S bonds as the main microstructural mechanism for γ-induced optical effects in this glass.