The lifetime of electrons, holes and excitons before self-trapping

Abstract

The authors discuss the self-trapping of a carrier or exciton in an insulator. The qualitative differences between small self-trapped molecular polarons and dielectric polarons are stressed. They point out that, for the formation of a molecular polaron or self-trapped exciton, a potential barrier must be penetrated or surmounted by the configuration coordinate, leading to a delay in the self-trapping process. This does not exist for dielectric polarons. The observable consequence of delay time before self-trapping is discussed, and applications are made to alkali halides and to SiO₂.