Triplet exciton dynamics: Exciton phonon scattering at low temperature

Abstract

In this paper, we calculate the k→k′ scattering rates of excitons by acoustic phonons. We consider two-phonon processes only, having considered one-phonon processes in an earlier paper. We treat one-phonon events and a single two-phonon event in both pure and impure crystals. We apply these results to the recent experimental work on tetrachlorobenzene and discuss the dependence of the rates on energy mismatch.