Resonance Raman studies in Cu2O. II. The yellow and green excitonic series

Abstract

Resonant Raman scattering of multiphonon modes has been studied in Cu2O in the region of its yellow and green excitonic series. Resonant enhancements of a large number of Raman modes have been observed. The experimental results have been interpreted quantitatively in terms of three kinds of exciton-phonon scattering processes: (i) intra-yellow-exciton scattering-depending on the energy of the yellow exciton, the phonons involved are the infrared active Γ15- (660 cm-1) or the Γ12- (109 cm-1) and Γ15- (154 cm-1) modes; (ii) interexciton scattering between the 2P green exciton state and yellow excitons continuum-the phonon responsible for this scattering process is the high-energy Γ15- mode; and (iii) intra-green-exciton scattering-only the low-energy Γ15- mode is involved. From these results a detailed picture of the relaxation mechanisms of the yellow and green excitons in Cu2O by emission of phonons is obtained. © 1978 The American Physical Society.