Thermoluminescence and photoluminescence of LiNaSO 4:Eu irradiated with 24 and 48 MeV 7Li ion beam

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Thermoluminescence (TL) of LiNaSO 4:Eu phosphor, irradiated with 24 and 48 MeV 7Li ions at different fluences in the range 5×10 9–1×10 12 ion/cm 2, has been studied. The samples from the same batch were also exposed to γ-rays from a Cs 137 source for comparative studies. The TL glow curves of the materials, irradiated with 7Li ions, have similar structures to that of γ-irradiated sample. They have a simple structure with a prominent peak at 412 K along with small one at around 481 K. The intensity ratios of 412–481 K peaks have been observed to increase with fluence increasing, while that of γ-irradiated sample shows a reverse trend. This could be attributed to the changes in the recombination center populations due to 7Li ions, that have been implanted inside the matrix of LiNaSO 4:Eu, during irradiation and might also act as a source for new trapping and luminescent centers. The implantation has been confirmed by TRIM calculations. The penetration depths (where the ion comes to rest) are found to be 145 and 463 μm corresponding to 24 and 48 MeV ion beam energies, respectively, which are less than the thickness of the sample chips (∼800 μm). The efficiencies of LiNaSO 4:Eu to 24 and 48 MeV 7Li ions measured relative to γ-rays of Cs 137 are found to be 0.007 and 0.024, respectively. Theoretical analysis of the glow curves of the samples irradiated by 7Li ions and γ-rays were done by glow curve deconvolution method to determine trapping parameters of various peaks. The experimentally observed linearity/sublinearity has been discussed in the frame of track interaction model. Photoluminescence studies in the 7Li ions irradiated and un-irradiated samples show that europium ions have incorporated in the host in their divalent (emission at 440 nm) as well as trivalent (emissions at 594, 615 and 700 nm) forms. The intensities of the emission bands of these ions have been observed to increase with fluence increasing.