Thermoluminescence of KCl Crystals Annealed in Chlorine Gas

Abstract

Thermoluminescence in the range from room temperature to 200°C was found on X-rayed KCl crystals which previously were annealed in chlorine gas. The glow curve of the emission at 2.8 eV exhibits evident peaks at 95°C and 145°C. Dependencies of the emission yield on X-irradiation time and on heating process were investigated. The emission around 145°C is attributed to interaction between F centers and V_F centers which are generated with thermal dissociation of extra chlorine molecules introduced by the annealing. The emission around 95°C is attributed to interaction between F centers and the V_F centers which are released from trapps by thermal stimulation. The dissociation energy and the activation energy to release are estimated approximately to be 2.1 eV and 1.3 eV, respectively. The (Remark: Graphics omitted.) is proposed as a model of the extra chlorine molecule.