Size dependence of acoustic and optical vibrational modes of CdSe nanocrystals in glasses

The size dependence of resonant Raman scattering from acoustic and optical vibrational modes in CdSe nanocrystals (size less than 10 nm) embedded in a glassy matrix has been investigated. In the low-frequency Raman scattering range (< 100 cm(-1)) a fine structure due to the confinement of acoustic modes is observed. The Raman line corresponding to the interaction with the optical modes (new 210 cm(-1)) shifts and widens with a decreasing of the particle size. These experimental results can be described by a single model based on the size dependence of the eigenvibration modes of spherical particles in a matrix.