Luminescence During Intermittent Electron Bombardment

Abstract

The dynamic luminescence characteristics of five samples of commercial phosphors excited intermittently by electron bombardment have been studied. The decay of artificial willemite follows closely a simple exponential law, except for a rapid fall during the first three milliseconds after bombardment, the prominence of this component increasing with the current density. An attempt is made to correlate the observed dependence of build‐up rate on current density with the phenomenon of current‐saturation under continuous bombardment. A sample of calcium tungstate follows changes in the intensity of excitation within 100 microseconds, the resolving time of the apparatus. Two samples of ZnS·Ag and one sample of ZnS·CdS·Ag decay more rapidly the higher the intensity of excitation. The initial rate for ZnS·Ag is greater than would be predicted for a simple bimolecular reaction, and cannot plausibly be explained by non‐uniformity in the initial distribution of reactants in a bimolecular reaction. The ZnS·CdS·Ag decays initially according to a simple bimolecular law.