Effect of retrapping on photostimulated luminescence in Sr3 SiO5: Eu2+, Dy3+ phosphor

Sr₃ SiO₅: Eu²⁺, Dy³⁺ exhibits a strong orange phosphorescence and photostimulated luminescence, originating from 4 f⁶ 5d-4 f⁷ transition of Eu²⁺, after ultraviolet exposure. Shallow and deep traps are evidenced by thermoluminescence spectrum and decay curve of phosphorescence, which consists of a very fast and a slow component. The photostimulated luminescence presents a slow rising and a falling edge as an infrared excitation at 808 nm is turned on and off, respectively. This is attributed to the result of electron retrapping by shallow traps based on the analysis of dynamical process in photostimulated luminescence involved in photostimulated depopulation of deep traps. The electrons retrapped by deep traps is also demonstrated in the time interval between photostimulation off and on, which results in an enhanced rising edge relative to the former falling edge.