The decay of phosphors under the influence of stimulating radiation can be investigated in a manner which avoids some of the complications impairing the significance of most decay measurements. The stimulated decay of an infra-red-sensitive strontium sulfide phosphor was measured. The complicating influence of spontaneous decay was practically eliminated. A phosphor with comparatively weak absorption of the stimulating and of the exciting radiation was selected and an extremely thin layer of the material was used, so that homogeneous excitation and stimulation were secured. The procedures of exhausting the phosphor and of measuring its stimulability were separated in principle and the stimulating intensity was kept constant throughout the exhaustion. The sensitivity to stimulation was measured over a range of six powers of ten, and the forced decay was carried to nearly complete exhaustion of the phosphor. This made it possible to determine the residual light-sum over a large range, and a region of very weak excitation of the phosphor was included. A further elimination of complicating factors is achieved by studying the infra-red-sensitivity as a function of the residual light-sum. The results of these measurements show strong evidence of second-order kinetics for the later stages of decay.
A suggestion that a certain kind of superposition of second-order processes should lead to an exponential asymptotic behavior of the decay is shown to be based on a fallacy.
© 1949 Optical Society of AmericaFull Article | PDF Article
OSA Recommended Articles
Frank J. Studer and Alma Rosenbaum
J. Opt. Soc. Am. 39(8) 685-689 (1949)
Richard H. Bube
J. Opt. Soc. Am. 39(8) 681-684 (1949)
F. R. Scott, R. H. Thompson, and R. T. Ellickson
J. Opt. Soc. Am. 39(1) 64-67 (1949)