Luminescence and laser Raman studies on gamma-irradiated RbI:Sm3+ crystals

This paper reports results of the photoluminescence (PL), thermoluminescence (TL) optical absorption and laser Raman scattering (LRS) studies on RbI:Sm3+ crystals. Sm when doped in the RbI crystals is found to enter in the trivalent state. Interestingly, it is found that the samarium ions act as electron traps and as electron donors as well on gamma irradiation. TL emission studies confirm this interesting be-havior. The PL spectrum exhibits the characteristic red/orange emission of the Sm ions corresponding to 4G5/2 → 6H9/2 (red) and 4G5/2 → 6H7/2 (orange) transitions. The TL glow indicates that the process is due to two different kinds of traps. Z3 centers are observed on optical treatment and a TL glow peak attributable to them is identified. Aggregation of V centers during the TL process is observed. Laser Raman scattering (LRS) of gamma-irradiated crystals contains two lines at 111 cm-1 and at 150 cm-1 attributable to I-3 (ions). On prolonged irradiation to γ-rays, RbI:Sm3+ crystals exhibit a strong line at 180 cm-1, which is attributable to I-5 (ions). TL emission spectra contain the Sm3+ emissions. From PSL and TL emission studies, the TL process is identified to be due to the thermal release of F electrons and their recombination with their counterparts. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)