Resonant Raman spectroscopy of confined and surface phonons in CdSe-capped CdS nanoparticles

A series of colloidal CdS/CdSe heteronanoparticles are studied by resonant Raman spectroscopy. The Raman-active phonons of both CdS-core and CdSe-shell are monitored upon a gradual increase of the shell thickness. Noticeable differences between the Raman spectra taken at different excitation wavelengths are observed, which can be related to different resonant conditions for different vibrational modes at a certain excitation wavelength. The possible morphology transformation of the CdSe shell with increase of its thickness is discussed, based on the correlation between changes in phonon spectra of the nanoparticles and the spectra of photoluminescence and optical absorption. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)