The role of retrapping in dose dependence of pulsed optically stimulated luminescence

Superlinear behaviour has been observed in dose dependence measurements of optically stimulated luminescence (OSL). Previous theoretical work has shown that superlinearity of the integral under the OSL decay curve may occur, resulting from competition with either radiationless luminescence centres or disconnected trapping states. Also, it has recently been shown that if OSL is measured during a relatively short pulse of stimulating light, quadratic dose dependence may take place even when only one trapping state and one kind of recombination centre take part. Here, the conditions for superlinear dose dependence, quadratic and more, to occur are considered. Also, the dose dependence of 'pulsed OSL' is discussed. In this procedure, the luminescence is only detected after the end of the stimulating light pulse; it is shown that when retrapping is relatively strong and initially the traps and centres are empty, superlinear dose dependence is expected. (author)