EXCITON-STATES OF LITHIUM HYDRIDE IN LIH1-XFX SOLID-SOLUTIONS

Exciton states of LiH1-xFx in the exciton band of lithium hydride are investigated by optical methods. It was found that spectra of the lowe st-energy exciton band of these crystals follow the persistent type of behaviour. The relation of exciton energy to solution composition poi nts to the effect of symmetry changes of the conduction band bottom an d average sizes of lithium hydride clusters. The structure of the lumi nescence spectra is determined by direct, phonon-forbidden indirect, o r disorder-assisted quasidirect transitions with increasing fluorine c ontent.