First‐order resonant Raman scattering in mixed silver halides

Abstract
Experiments of resonant Raman scattering in mixed crystals of AgBr:AgCl at low temperatures are performed. The spectra of the mixed crystals differ in a qualitative fashion from the spectra of pure AgBr. In particular, strong first‐order resonant Raman scattering is reported hitherto not observed. The results can be interpreted in terms of a relaxation in the momentum conservation caused by the perturbing system. Intervalley scattering by TA(X) and LA(X) phonons and intraband scattering by LO(Γ) phonons are found to be effective relaxation mechanisms for the exciton.