Size effects on Raman spectra of small CdSe nanoparticles in polymer films

The results of a resonant Raman scattering (RRS) study of polymer-stabilized colloidal CdSe nanoparticles (NPs) are reported. The size-selective nature of the RRS is demonstrated by analysing the NP ensembles with different average size (d) over bar and size distribution Delta d using a set of excitation wavelengths. The effect of size selection on the estimation of (d) over bar and Delta d values from the RRS spectra is discussed, as well as some peculiarities of RRS on surface optical phonons. From the experimentally observed small variation of the I-2LO/I-LO ratio for 2-5 nm NPs a minor effect of (d) over bar on the electron-phonon coupling strength in this (d) over bar range is supposed.