Stimulated luminescence and photo-gated hole burning in BaFCl 0.8Br 0.2:Sm 2+,Sm 3+ phosphors

Abstract

The photo- and thermo-stimulated luminescence (PSL and TSL) of BaFCl 0.8Br 0.2:Sm 2+,Sm 3+ phosphors were investigated. It is found that the stimulated luminescence intensity of Sm 2+ is almost equal to that of Sm 3+ even if the content of Sm 2+ is much lower than that of Sm 3+. Only the stimulated luminescence of Sm 2+ is observed in the sample in which the content of Sm 2+ is much higher than Sm 3+, demonstrating that the PSL or TSL efficiency of Sm 2+ is much higher than that of Sm 3+. This is attributed to the effective overlap of the e–h emission with the absorption of Sm 2+ centers which may make the energy transfer from the electron–hole pairs to Sm 2+ effectively. In BaFCl 0.8Br 0.2:Sm 2+,Sm 3+ the stimulated luminescence is considered to be occurred via the recombination of photoreleased electrons with the [Sm 2++h] or [Sm 3++h] complex and the energy transfer from the electron–hole pairs to the luminescence centers (Sm 2+ and Sm 3+) is concerned to be the major step to determine the stimulated luminescence efficiency. The X-ray-induced stimulated luminescence is compared and connected to the photon-gated hole burning. The net result of the two processes is quite similar and may be comparable. It is suggested from the observations of stimulated luminescence that electron migration between Sm 2+ and Sm 3+ is not the major process, color centers may play an important role in hole burning. The information from stimulated luminescence is helpful for the understanding of the hole burning mechanism.