Optical Absorption and Thermoluminescence of X-Ray-Irradiated KBr Crystals at Room Temperature

Two thermoluminescence peaks are observed in KBr crystals that are x irradiated at room temperature. The 185°C peak can be removed by annealing the crystal for several hours at 400°C and is attributed to highly localized defects. The 152°C peak is proposed to be due to the liberation and recombination of the electrons from the $F$ centers. The single glow peak obtained at 152°C is analyzed by the area method and initial-rise method to give thermal trap depths of 0.55 ± 0.04 and 0.61 ± 0.02 eV, respectively. The optical absorption measurements indicate that $F$ and $V_2$ centers are formed in the crystal during the x-irradiation process. The thermoluminescence spectra has been analyzed to consist of one narrow emission band centered at 3.08 eV. This thermoluminescence process is found to be nearly first order and an energy-level diagram is proposed to correlate the optical absorption and emission spectra.