Vibrational Raman spectra of CdSxSe1-x magic-size nanocrystals

Resonant Raman scattering spectra of ultrasmall (<2 nm) magic-size nanocrystals (NCs) are reported. The spectra of CdS and CdSxSe1-x NCs, resonantly excited with 325 nm and 442 nm laser lines, correspondingly, reveal broad features in the range of bulk optical phonons. The relatively large width, similar to 50 cm(-1), and downward shift, similar to 20 cm(-1), of the Raman bands with respect to the longitudinal optical phonon in bulk crystals and large NCs are discussed based on the breaking of the translational symmetry and bond distortion in these ultrasmall NCs. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim