Structure of the short-lived absorption and luminescence spectra of barium and calcium fluorides accompanying pulsed electron irradiation

Abstract

It is established that the optical absorption in the hole and electron components of autolocalized excitons in BaF₂ excited by a pulsed electron beam consists of a collection of overlapping bands with a half-width no greater than 0.1 eV. Simultaneous subexcitation with the stimulated emission of II–VI semiconductors made it possible to isolate three groups of bands, caused, by analogy with CaF₂ [Phys. Solid State 39, 1060 (1997)], by different configurations of autolocalized excitons in the fluorite lattice. The process of radiative decay of autolocalized excitons in CaF₂ and BaF₂ when they are optically excited in the region of the electron component of the absorption has been detected. The spectral rate parameters of the radiation that appears during simultaneous subexcitation coincide with the characteristics of the radiation ascribed earlier to core-valence transitions. The photostimulated variation of the absorption spectra of autolocalized excitons is accompanied by selective variation of the luminescence spectra of autolocalized excitons, which also is evidence of their complex spectral content.