Size-dependence of the anharmonicities in the vibrational potential of colloidal CdSe nanocrystals

We investigated multi-phonon processes in two types of CdSe nanocrystals spherical quantum dots and nanorods by temperature-dependent Raman spectroscopy We find the anharmonic constants relating to the two- and three-phonon decay channels to systematically change with changing nanocrystal size The contributions from two-phonon processes decrease with decreasing diameter while the contributions from higher-order processes increase The anharmonicities in the vibrational potential increase due to the phonon confinement and we did not find a shape dependence (C) 2010 Elsevier Ltd All rights reserved