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Light-induced structural changes of As-S glasses and films were probed both by macro FT-Raman and photon-energy dependent micro-Raman spectroscopy using different spectral composition of photoactive light: polychromatic or different wavelengths of laser radiation. The polychromatic illumination and thermal treatment leads to continuous decrease in intensity of characteristics vibrational modes of molecular or cage-like species like As4S4, As4S3, etc. Under laser illumination the picture is different, new observed features in the Raman spectra of As-rich As-S glass are related to transformations of As4S4 molecules: α(β)-As4S4 transform into pararealgar p -As4S4 form during laser illumination. The effectiveness of transformations depends mainly on photon energies used for irradiation, but the tendency to transform is observed for all used photon energies ranging from 1.65 to 2.54 eV. Experimental photon-energy dependent Raman spectroscopy used together with ab initio DFT calculations indicate that the mechanism of photo-induced changes in As-S glasses and films is defined by spectral width of illumination source (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The comparative analysis of the calculated and experimental Raman spectra of non-crystalline As2S3, Bi2S3 and Sb2S3 films (i.e. with exchanging As to Sb, Bi) obtained by flash evaporation on glassy and silicon substrates was performed. The spectra were interpreted and analysed using the results of molecular modelling and ab initio calculations. The structural models used for calculations include both basic building blocks and other types of atomic clusters known for As-S, Bi-S, and Sb-S binary systems. The influence of atomic substitution on the nanostructure of flash evaporated As(Sb,Bi)2S3 films were investigated, observed photo-induced phenomena and related peculiarities were analysed using results of ab initio calculations and discussed in detail. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)