Phonon broadening of emission spectra for STE and Auger-free luminescence

The temperature dependencies of the bandwidths for self-trapped exciton emission spectra in several alkali halide crystals with high temperature of thermal quenching for self-trapped exciton emission (NaBr, KI, CsI) have been studied and compared with a typical temperature behavior of Auger-free luminescence spectra. It was shown that different phonon modes are responsible for broadening of emission band for different types of self-trapped excitons as well as for different bands in the spectrum of Auger-free luminescence. The features found indicate that the lattice structure of emitting state for Auger-free luminescence has most probably the on-center character.