Stimulated luminescence and photo-gated hole burning in BaFCl0.8Br0.2 : Sm2+,Sm3+ phosphors

The photo- and thermo-stimulated luminescence (PSL and TSL) of BaFCl0.8Br0. 2:Sm2+,Sm3+ phosphors were investigated. It is found that the stimulated lu minescence intensity of Sm2+ is almost equal to that of Sm3+ even if the co ntent of Sm2+ is much lower than that of Sm3+. Only the stimulated luminesc ence of Sm2+ is observed in the sample in which the content of Sm2+ is much higher than Sm3+, demonstrating that the PSL or TSL efficiency of Sm2+ is much higher than that of Sm3+. This is attributed to the effective overlap of the e-h emission with the absorption of Sm2+ centers which may make the energy transfer from the electron-hole pairs to Sm2+ effectively. In BaFCl0 .8Br0.2:Sm2+,Sm3+ the stimulated luminescence is considered to be occurred via the recombination of photoreleased electrons with the [Sm2+ + h] or [Sm 3+ + h] complex and the energy transfer from the electron-hole pairs to the luminescence centers (Sm2+ and Sm3+) is concerned to be the major step to determine the stimulated luminescence efficiency. The X-ray-induced stimula ted luminescence is compared and connected to the photon gated hole burning . The net result of the two processes is quite similar and may be comparabl e. It is suggested from the observations of stimulated luminescence that el ectron migration between Sm2+ and Sm3+ is not the major process, color cent ers may play an important role in hole burning. The information from stimul ated luminescence is helpful for the understanding of the hole burning mech anism. (C) 1999 Elsevier Science Ltd. All rights reserved.