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A systematic study on ternary As-S-Se glass, chalcogen-rich versus well-studied stochiometric compositions is carried out using Raman, x-ray photoelectron, and extended x-ray absorption fine structure spectroscopies. Results provide insight into the structural units and evidence for the existence of homopolar bonds that are the possible structural origin of the high nonlinearity in these glasses.

We have studied the kinetics of photoinduced effects in nanolayered Se/As2S3 film by in situ optical absorption measurements, which reveal that photodarkening in these films is followed by photoinduced diffusion. An increase in disorder during photodarkening and its subsequent decrease during photoinduced diffusion were also observed. The observation of photodarkening of Se at room temperature when confined between As2S3 layers suggests that the glass transition temperature of Se shifts to higher energy. The analysis shows that the atoms which take part in photodarkening play a vital role in photoinduced diffusion. The x-ray photoelectron spectroscopy measurements show the atomic movements during photoinduced diffusion. It also shows that some of the As–S bonds are converted into As–Se bonds. Since it is energetically difficult to break an As–S bond to form an As–Se bond, we assume that the new bond formations are taking place by the bond rearrangement mechanism. [ABSTRACT FROM AUTHOR]

Chalcogenide glasses have attracted considerable attention and found various applications due to their infrared transparency and other optical properties. The As–S–Se chalcogenide glass, with its large glass-formation domain and favorable nonlinear property, is a promising candidate system for tailoring important optical properties through modification of glass composition. In this context, a systematic study on ternary As–S–Se glass, chalcogen-rich versus well-studied stochiometric compositions, has been carried out using three different techniques: Raman spectroscopy, x-ray photoelectron spectroscopy, and extended x-ray absorption fine structure spectroscopy. These complementary techniques lead to a consistent understanding of the role of S/Se ratio in chalcogen-rich As–S–Se glasses, as compared to stochiometric composition, and to provide insight into the structural units (such as the mixed pyramidal units) and evidence for the existence of homopolar bonds (such as Se–Se, S–S, and Se–S), which are the possible structural origin of the high nonlinearity in these glasses. [ABSTRACT FROM AUTHOR]

An in situ optical absorption measurements are performed to explore the kinetics of photoinduced effects in nanolayered Se/[As.sub.2][S.sub.3] films. The analysis showed that the atoms taking part in photodarkening play a vital role in photoinduced diffusion.

An investigation on the structural origin of reversible [gamma]-induced effects in vitreous Ge23.5Sb11.8S64.7 is conducted by high-resolution X-ray photoelectron spectroscopy (XPS). The changes in valence band spectrum from [gamma]-irradiation point to a decrease of sulfur lone pair electron concentration accompanied by changes in bonding states of S and Ge.

High-resolution X-ray photoelectron spectroscopy is used to identify the mechanism of X-ray-induced Ag diffusion into Ge30Se70 chalcogenide glass thin films, which are prepared in situ to avoid oxygen contamination. From the analysis of Ge 3d, Se 3d, and Ag 3d core levels, and valence band spectra, changes in the electronic structure are determined as Ag diffuses gradually with increasing irradiation. The ternary phase based on Ge2Se6 units, which contains homopolar Ge–Ge bonds, forms when diffusion approaches equilibrium where Ag content ∼30 at.%. The formation of a Se-rich composition is indicated in the near-surface region at the initial stage of the process, but the previously assumed Ag2Se phase is not detected. [ABSTRACT FROM AUTHOR]