Conversion of F⇆F + centers in anion-defective corundum crystals

The method of photostimulated electron emission is used to investigate the processes responsible for redistributing charges formed by photoionization of F centers in anion-defective corundum single crystals in an external electric field. It is shown that the observed features of the excitation spectra are due to conversion transitions between F and F ⁺ centers, whose probability in the surface layer of the crystal is much higher than in the interior because of the high excitation density and the presence of an electric field. The results obtained could be of interest for studying radiation-stimulated phenomena in dielectric materials. Pis’ma Zh. Tekh. Fiz. 25, 66–70 (October 12, 1999)