Excition luminescence of LiH1 − xFx solid solutions

Excition states of LiH1 − xFx in the exciton band of lithium hydride are investigated by optical methods. The measurements of the decay times of free and bound excitons in LiH1 − xFx crystals were performed at the optical spectroscopy station in the SR channel on the VEPP-3 storage ring. It was found that the spectra of the lowest-energy exciton band of these crystals followed a persistent type of behaviour. The relation of exciton energy to solution composition points to the effect of symmetry changes of the conduction band bottom and the average sizes of lithium hydride clusters. The structure of the luminescence spectra is determined by direct, indirect or disorder-assisted quasidirect transitions with an increase of the fluorine content.