Relaxation of Electron-Phonon System in Optically Excited Quasi-1-D Mixed Valence Crystal Wolffram's Red Salt

Abstract

Resonance Raman scattering and photo-luminescence in Wolffram's red salt are studied. Together with a Raman line and its overtones due to chlorine vibrations along the chain, a continuous, flat and Raman-like emission is observed in the emission spectra. The latter extends deeply into the band edge and is followed by aprominent luminescence band. These emission bands are explained in terms of the recombination during and after relaxation of a charge transfer excited state to the self-trapped state. Details of the relaxation process are discussed on the basis of experimental results on the spectral shapes, the intensities and the degree of polarization of the spectra. These experimental results provide the direct evidences for the characteristic relaxation process in self-trapping in a 1-d electron-phonon system.