Thermoluminescence of thallium-doped BaFCl

The effect of doping of Tl upon thermoluminescence, its emission and optical absorption in flux grown BaFCl crystals is investigated. Besides an increase in luminescence output, X/γ-irradiations of BaFCl:Tl crystals produce three additional glow peaks at 450, 465, and 500 K and a TL emission spectrum at 460 nm. Optical absorption studies reveal two small bands at 340 and 650 nm. Room temperature annealing studies indicate that the three glow peaks at 450, 465, 500 K and the optical absorption band at 650 nm are more stable than others present in undoped crystals. Thus the additional glow peaks are attributed to the detrapping of electrons from the substantial number of metastable energy levels as populated by the thallium impurity and subsequent radiative recombination with holes. The trap depth and frequency factor are calculated employing various methods. (author)