We report unusual spectral features in the resonant Raman scattering spectra of colloidal
CdSe nanoparticles as small as 2–3 nm. High-frequency shoulders of the longitudinal
optical phonon peak and its overtones were observed and their dependence on the
excitation wavelength, temperature, nanoparticle size, and surface passivation with ZnS
shell studied. As the probable origin of the uncommon spectral feature the participation of
acoustic phonons and manifestation of the density of surface-related vibrational states is …