Specific features in low-frequency vibrations of nanocrystals in fluorophosphate glassy matrices

A Raman scattering study of low-frequency vibrational spectra of mixed cadmium sulfoselenide nanocrystals in a fluorophosphate glassy matrix is reported. The measurements have revealed a low-frequency feature in the nanocrystal density of states, whose frequency is related to the glass-matrix annealing time and, hence, to the size of the nanocrystals prepared, which is interpreted as a manifestation of the size quantization effect. Besides the line associated with the constraints on the longitudinal acoustic wave in a nanocrystal, a lower-frequency feature assigned to torsional vibrations of a nonspherical nanocrystal has been found. (C) 1999 American Institute of Physics. [S1063-7834(99)03707-7].