Radiation induced aggregation and thermoluminescence of copper centers in KCl

The influence of the impurity aggregation state on the absorption and luminescence spectra of KCl:Cu irradiated at room temperature has been studied. Unirradiated samples excited with UV light show two main emission bands at 400 and 420 nm, ascribed to isolated Cu+ ions and copper aggregates respectively. The same emission bands appear in the thermoluminescence spectra. The F and M bands show annealing steps simultaneous with the glow peaks. It is shown that the radiation induced Cu- and Cu0 centers can be electrically compensated by anion vacancies. It is suggested that radiation induces impurity aggregation as well as anion interstitial aggregation. Thermal release of interstitials may excite isolated Cu+ ions and copper aggregates, either through energy transfer from F + H recombination or by H + α -> Vsub(K), Vsub(K) + Cu0 reactions. (author)