The Significance of the Temperature Dependence of Fluorescence Intensity

Abstract

For some phosphors the fluorescence intensity increases with increasing temperature, reaches a maximum, and then decreases. This behavior arises from a competition of an increasing absorption for the exciting radiation and thermal quenching of the emitted radiation. However, the slope of the initial rise of fluorescence and the temperature of the maximum also depend rather strongly on the thickness of the sample considered. Thin samples, i.e., those in which the penetrating exciting radiation is not absorbed completely, in comparison with thick samples exhibit a steeper slope and a maximum at higher temperature. If the phosphor is in powder form, the average particle size also influences the slope and the position of the maximum although generally to a lesser degree than the sample thickness. Experimental data are presented for magnesium fluorogermanate and magnesium fluoroarsenate, both activated with manganese.