Optically induced F-centre-interstitial recombination in γ-irradiated KCl

In single crystals of KCl irradiated with gamma rays at room temperature, the relationship between the photoluminescence emitted at 440 nm induced by shining F light on the irradiated samples and the thermoluminescence of these samples has been studied. It has been concluded that this photoluminescence is due to the recombination of F centres and trapped interstitials (chlorine atoms). Under the action of light, the F centres migrate through the lattice; when an F centre gets close to a trapped interstitial, they recombine and light is emitted. It has been found that mobile F centres are formed when anion vacancies trap electrons which are thermally or optically released from traps. It is concluded that the F* centre is the mobile entity in these experiments.