Evidence for formation of Se molecular clusters during precipitation of CdSe1−xSx nanoparticles in glass

While studying the effect of thermal treatment at 625–700°C on the formation of borosilicate glass-embedded CdSe or CdSe 1− x S x nanocrystals, pronounced bands at 323 and 646 cm −1 were observed in the Raman spectra. They are assigned to Se 2 clusters on the base of their frequency positions, widths, intensities, and resonance behavior. The precipitation of Se 2 molecular clusters in borosilicate glass is shown to occur when the heat treatment temperature and/or duration are beyond the range, most suitable for the formation of CdSe or CdSe-rich CdSe 1− x S x nanocrystals.