Thermoluminescence andF-Center Bleaching in Heavily Irradiated KCl

The possibility that thermoluminescence from KCl crystals electron irradiated at 80^∘{}K can cause optical bleaching of the crystals and be responsible for the aggregation of F centers has been investigated. It was found that even though two of the thermoluminescent glow peaks occurred at the temperatures where F^' centers annealed out (200^∘{}K) and M centers were formed (260^∘{}K), the intensity of the luminescence was much too weak to be the cause of the observed changes. Furthermore, F-center annealing was observed to occur over a broad temperature range and could not be correlated with any particular glow peak. Three different emission spectra were observed, each being characteristic of a different temperature range.