Optical absorption, photoluminescence, photostimulated luminescence (PSL) and thermoluminescence (TL) studies on RbBr : Tb 3+ crystals irradiated with X-rays is reported. The optical absorption in the UV region confirms the presence of terbium in the host matrix in the trivalent state. Photoluminescence of these crystals exhibits characteristic Tb 3+ emissions due to transitions from the 5 D 3 and 5 D 4 levels to various levels of the 7 F septet. On F-bleaching X-irradiated crystals Z 3 centers are observed. The TL glow curve indicates a two-step thermal annihilation process for the radiatively created defects. The presence of the characteristic emissions due to terbium ions in the photostimulation at the F band confirms the participation of Tb ions in the defect-production process. Trap parameters for the TL process are calculated and presented. Emissions under the TL glow peaks contain the characteristic emissions of Tb 3+ in addition to the emission due to the recombination of the F electron with V-type centers.
Optical absorption, photoluminescence, thermoluminescence (TL) and photostimulated luminescence (PSL) studies on RbI:Tb(3+) crystals irradiated with gamma-rays is reported. Photoluminescence of these crystals exhibits characteristic Tb(3+) emissions, due to transitions from the (5)D(3) and (5)D(4) levels to various levels of the (7)F septet. On F-bleaching the gamma-irradiated crystals, Z(3) centres are observed. The TL glow curve indicates a two-step thermal annihilation process for the radiatively created defects. The presence of the characteristic emissions due to terbium ions in the photostimulation at the F-band, and TL emissions under both glow peaks, confirm the participation of Tb ions in the defect production and recombination processes. Trap parameters for the TL process are calculated and presented. The low temperature glow peak is attributable to Z(3) centres.
This paper reports results of the photoluminescence (PL), thermoluminescence (TL) optical absorption and laser Raman scattering (LRS) studies on RbI : Sm 3+ 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 behavior. The PL spectrum exhibits the characteristic red/orange emission of the Sm ions corresponding to 4 G 5/2 → 6 H 9/2 (red) andH 7/2 (orange) transitions. The TL glow indicates that the process is due to two different kinds of traps. Z 3 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 3 I -(ions). On prolonged irradiation to γ-rays, RbI : Sm 3+ crystals exhibit a strong line at 180 cm -1 , which is attributable to 5 I -(ions). TL emission spectra contain the Sm 3+ 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.
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