Thermo- and photostimulated luminescence and stimulated emission of magnesium oxide crystals irradiated in a nuclear reactor

The luminescence of nominally pure magnesium oxide crystals irradiated in a nuclear reactor is studied. It is shown that, in the entire fluence range (1015–1018 n/cm2), the active luminescence centers are chromium impurity ions, which are initially ( 1017 n/cm2), after the radiation-induced transformation Cr2+ → Cr3+, are in the form of Cr3+ ions. The role played by F centers is also shown. Pulsed stimulated emission is observed in crystals irradiated with a fluence of 1018 n/cm2.