Second- and third-order Raman scattering in bulk and glass-embedded nanometric CdS1 – xSex crystals

Second- and third-order Raman spectra of bulk and nanometric CdS1 – xSex crystals were measured. At off-resonance excitation conditions the second-order Raman spectra of bulk CdS1 – xSex exhibit anharmonic coupling of optical phonons and two-phonon states with the participation of acoustic phonons. Resonant Raman spectra of CdS1 – xSex single crystals with a strong enhancement of multiple LO phonon bands show the evidence for the strong electron-phonon coupling in bulk CdS1 – xSex crystals. From the ratio of intensities of multiple and single LO phonon bands in the resonance Raman spectra of the glass-embedded CdS1 – Sex nanocrystals one may conclude that the electron-phonon coupling in the nanocrystals is much smaller than in the corresponding bulk materials