Photoluminescence and EPR studies on gamma irradiated Ce 3+ doped potassium halide single crystals

Abstract

Electron Paramagnetic Resonance(EPR), Photoluminescence(PL), Thermoluminescence (TL) and other optical studies of γ-irradiated KBr, KCl:Ce 3+ single crystals. Cerium when doped into the KBr, KCl is found to enter the host lattice in its trivalent state and act as electron trap during γ-irradiation, thereby partially converting itself to Ce 2+. The Photoluminescence(PL) spectra of both KCl and KBr crystals doped with Ce exhibit the strong blue emissions of Ce corresponding to 5d( 2D)→ 2F 5/2 and 5d( 2D)→ 2F 7/2 transitions. The defect centers formed in the Ce 3+ doped KBr and KCl. Crystals are studied using the technique of EPR. A dominant TL glow peak at 374, 422 K and KCl:Ce 3+ at 466, 475 K is observed in the crystal. EPR studies indicate the presence at two centers at room temperature. Spectral distribution under the thermoluminescence emission(TLE) and optically stimulated emission(OSL) support the idea that defect annihilation process to be due to thermal release of F electron in KBr, KCl:Ce 3+ crystals. Both Ce 3+ and Ce 2+ emissions were observed in the thermoluminescence emission of the crystals.