Surface and confined optical phonons in CdS_xSe_1-x nanoparticles in a glass matrix

Abstract

We report first- and higher-order Raman scattering from the surface and confined optic phonons in CdS_0.65Se_0.35 and pure CdS nanoparticles embedded in glass matrix. The average particle sizes and size distribution have been estimated from the quantitative comparison of the blue-shifted optical-absorption spectra with the calculations based on the tight-binding model. The first-order asymmetric Raman line shape has been analyzed by including both the confined optic modes and the surface modes. The average particle sizes so obtained from this analysis compare well with those estimated from the optical-absorption spectra. The observed frequencies of the surface modes have been compared with the results of the dielectric response function model.