Characteristic features of spectrally resolved luminescence in crystalline phosphors

Wide gap crystalline phosphors are often used as luminescent solid state detectors in modern dosimetry of ionizing radiation. Typically, thermoluminescence (TL) and optically stimulated luminescence (OSL) phenomena are used for these purposes. This type of long lived luminescence is typically attributed to trapping and recombination of charge carriers at various defects of the solid. These defects are related to deep trap levels within the energy gap. Theoretical models predict localized, delocalized or semi-localized recombination route for the processes in various solids. The different routes may occur simultaneously during TL or OSL readout. Usually, it is difficult to distinguish these mechanisms. This paper presents some methods that allow to identify delocalized transitions from spectrally resolved TL, OSL and phosphorescence measurements. The methods were tested numerically to prove their applicability in typical cases.