Reflectance spectra and thermoluminescence of NaBr coloured in an electrodeless discharge

A comparative study of the optical and thermoluminescent properties ofγ irradiated NaBr and NaBr coloured in an electrodeless discharge is reported. In discharge coloured NaBrF centre absorption maxima shifted with the colouration time. This is tentatively attributed to the formation ofE centres. Correspondingly, an additional peak was observed in thermoluminescence glow curve. It is suggested that the results are not characteristic of the method of colouration but rather of the imperfections inherent to the powders, and in a perfect (undeformed) single crystal such a phenomenon should not be observed.