Abstract
The temperature dependence of the spectral composition has been presented by a new method which shows better the relative changes of the form of the emission band. On the main emission band of some zinc and zinc-cadmium sulphides, between the liquid air temperature and the temperature break-point, certain effects have been observed; these are that (a) below 180° K the short wave side of the emission band of all phosphors grows faster than the long wave side with increasing temperature, (b) that in the neighbourhood of 220° K, the intensity of the whole band has a minimum for all copper-activated and copper-contaminated phosphors, and that (c), above 220° K, some phosphors behave inversely as (a). These effects can be explained by the existence of two temperature-dependent processes having inverse influence on the form of the emission band, one being similar to the holemigration process and the other being in connexion with the thermal liberation of trapped electrons.