We have used resonant Raman and absorption edge spectroscopy together with first-principle calculations in order to study the structure of GeS 2 glasses (g-GeS 2 ). The glasses were prepared under different melt temperatures and cooling rates, which are shown to significantly influence the g-GeS 2 structure at the nano-scale. The combined use of Raman spectroscopy and ab initio calculations reveals the origin of the molecular level electronic structure and its connection to the interesting technological features of the g-GeS 2 . Local structure within the glasses is discussed in terms of atomic Ge n S m clusters. The band gaps computed for these clusters and their correlation to the experimental band gaps and the possible formation of band tail states are also discussed.

No abstract

The non‐linear two‐photon absorption coefficient (TPA) of ternary Ge‐As‐S glasses of different sections (As2S3‐GeS2, As2S3‐Ge2S3, As‐GeS2, As‐Ge2S3) was measured at 690 nm. The obtained data were interpreted based on the evolution of the glass structure and mean coordination number with the composition. Raman spectroscopy was used to investigate the bonding configuration of the glasses and the structural interpretation of the vibrational bands was performed based on DFT calculations of vibrational spectra of different types of As(Ge)nSm clusters and XPS measurements. It was found that the TPA is decreasing near the magic coordination numbers of 2.4 and 2.67. Relationship between TPA and nanophase separation in ternary glasses is discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

535.36:548Raleigh and Mandelshtam-Brillouin light scattering has been investigated in chalcogenide glasses of the (As 2 S 3 ) x I 1-x system for x = 1.00-0.80. Longitudinal hypersound velocities, adiabatic elastooptical constants (p 12 ) ad at frequencies of ~15 GHz, and Landau-Placzek ratios R LP are found and scattering losses are calculated. Significant iodine additives are shown to result in the appearance of different features in the behavior of concentration dependences of the investigated parameters.

The Rayleigh light scattering in chalcogenide glasslike alloys of the As-S system is investigated. The velocities of longitudinal hypersound, elasto-optical constants, extinction coefficients, and scattering losses have been determined. It is shown that an increase in the amount of sulfur in alloys leads to an increase in chemical differentiation and, as a result, to an increase in the intensity of Rayleigh scattering and in inherent optical losses.Introduction. The current progress in optical instrument engineering and techniques of median and far-IR ranges (2-25 µm) has given impetus to studying the optical properties of chalcogenide glasslike semiconductors (CGS) as optical materials that satisfy the most stringent requirements when being used as active or passive elements of optoelectronics. A significant part of chalcogenide glasslike semiconductors have good chemical and radiation stability, crystallization resistance, and high transparency, making it possible to synthesize materials with a wide range of optical and physicochemical parameters by changing the type and quantitative relationships between the cation and anion components of the glasses.At the present time, the widest practical usage has been gained by glasslike alloys of the As-S system. They are employed in fiber optics, laser IR-range techniques, optical pyrometry and infrared imaging, medicinal diagnosis, and gas analysis [1-6]. Attainment of the minimum possible (at a level of 0.2 dB/km at λ = 1.55 µm) fundamental optical losses in fused quartz has stimulated a considerable increase in investigations of materials transparent in a more