A STUDY OF THE SELF-TRAPPED EXCITON AND F-CENTER IN MGF2

The self-trapped excitons (STEs) and F centres in MgF2 are studied wit hin the extended-ion approximation. It is found that the STE is in bet a nearest-neighbour F-H pair with C-1 symmetry. The theoretical resul ts for the spectra of the STEs and F centres are in good agreement wit h experiments. The stable F-H pairs converted from STEs are generated only at the hole excited state of the STEs according to the calculatio ns of the adiabatical potential energy curve of the STE/FH pair. A mod el of the excited-hole hopping diffusion is proposed to explain the re orientation of the H centre and the formation of the F-H pair under ca scade excitation.