Thermoluminescence and other optical studies on RbBr:Tb 3+ crystals

2015

J Fluoresc

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This paper reports that KBr doubly doped with Tb(3+) and Ce(3+) were prepared by Bridgman-Stockbarger method and characterized by Optical absorption, Photoluminescence (PL), Thermoluminescence (TL), Photo stimulated emission (PSL) and TL emission, after X-ray irradiation have been observed. The optical absorption measurement indicates that F and Z3 centers are formed in the crystal during X-ray irradiation process. It was attempted to incorporate a broad band of Ce(3+) sensitizer into the narrow band emission of Tb(3+) in the KBr host without reduction of emission intensity. Co-doping of Ce(3+) ions in KBr:Tb(3+) crystal showed a broad band emission due to the d-f transition of Ce(3+) and a reduction in the intensity of emission peaks due to (5)days → (7)F6 transition of Tb(3+) when they were excited at 250 nm. These results supported that an effective energy transfer occurs from Ce(3+) to Tb(3+) in the KBr host. Co-doping Ce(3+) ions greatly intensified the excitation peak at 260 nm for the emission at 390 nm of Tb(3+) which means that more lattice defects, involved in the energy absorption and transfer to Tb(3+), are formed by the Ce(3+) co-doping. The integrated light intensity is two orders of magnitude higher as compared to the undoped samples for similar doses of irradiation and heating rate. Thermoluminescence process has been identified due to thermal mobilization of F-electrons and this causes peaks at 371 K and at 427 K, 457 K in KBr: Ce(3+), Tb(3+) crystals. The defects generated by irradiation were monitored by optical absorption and trap parameters for the TL process were calculated and presented.

Section: Introductionmentioning

confidence: 73%

“…This absorption is due to Tb 3+ [23]. The reappearance of the absorption around 255 nm on F-light bleaching subsequent to irradiation indicates the Tb 3+ acts as a hole trap, ie.…”

Section: Optical Absorptionmentioning

confidence: 96%

Section: Optical Absorptionmentioning

confidence: 98%

Section: Optical Absorptionmentioning

confidence: 99%

See 2 more Smart Citations

Luminescence Properties and Optical Absorption of X ray-Irradiated KBr: Ce3+, Tb3+ Crystals

Bangaru¹,

Saradha²,

2015

J Fluoresc

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“…A perturbed F center called a Z 3 center absorbs on the lower-wavelength side of the F band. Manimozhi et al [21] have also reported a similar kind of Z 3 centers in RbBr: Tb 3+ crystal. Considering this, it seems appropriate to assign the new absorption after F bleaching in the present work to Z 3 centers.…”

Section: +mentioning

confidence: 85%

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

Manimozhi

Physica Status Solidi (b)

2007

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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.

Thermoluminescence and photoluminescence studies on γ‐ray‐irradiated Ce³⁺,Tb³⁺‐doped potassium chloride single crystals

Bangaru¹,

Saradha²,

2015

Luminescence

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Single crystals of KCl doped with Ce(3+),Tb(3+) were grown using the Bridgeman-Stockbarger technique. Thermoluminescence (TL), optical absorption, photoluminescence (PL), photo-stimulated luminescence (PSL), and thermal-stimulated luminescence (TSL) properties were studied after γ-ray irradiation at room temperature. The glow curve of the γ-ray-irradiated crystal exhibits three peaks at 420, 470 and 525 K. F-Light bleaching (560 nm) leads to a drastic change in the TL glow curve. The optical absorption measurements indicate that F- and V-centres are formed in the crystal during γ-ray irradiation. It was attempted to incorporate a broad band of cerium activator into the narrow band of terbium in the KCl host without a reduction in the emission intensity. Cerium co-doped KCl:Tb crystals showed broad band emission due to the d-f transition of cerium and a reduction in the intensity of the emission peak due to (5)D3 -(7)F(j) (j = 3, 4) transition of terbium, when excited at 330 nm. These results support that energy transfer occurs from cerium to terbium in the KCl host. Co-doping Ce(3+) ions greatly intensified the excitation peak at 339 nm for the emission at 400 nm of Tb(3+). The emission due to Tb(3+) ions was confirmed by PSL and TSL spectra.