Luminescence ofF+centers in CaO crystals under pulsed-laser excitation

Abstract
Luminescence of F+ centers (oxygen vacancies each with one electron) has been investigated in thermochemically reduced, electron-irradiated, and neutron-irradiated CaO crystals. Time-dependent emission spectra following laser excitation into the F+ absorption band at 351 nm were measured for the three types of crystals. We observed a fast component with a lifetime ≤10 ns and a slow decay attributed to charge trapping and transport. The intensity and decay kinetics of the F+ phosphorescence depended on the method by which the defects had been produced. Estimated gain coefficients for stimulated emission under pulsed laser pumping are less than 0.1 cm1. These values are significantly smaller than the absorption coefficient at the emission wavelength.