Abstract
Photoluminescence (PL), photostimulated luminescence (PSL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) studies were carried out on LiYF 4:U 4+ and pure LiYF 4 crystals. The PL and EPR investigations have identified the presence of Eu 3+, Tb 3+ and Gd 3+ ions in both of these crystals possibly due to their existence in the starting materials. The luminescence observed during afterglow, PSL and TSL revealed that emission occurs at wavelength positions 382, 413, 437 and 544 nm , which are characteristic of Tb 3+ ions. The present investigations using PSL and TSL in combination with PL studies before and after gamma irradiation have revealed that selective energy transfer to Tb 3+ ions occurs during electron–hole recombination processes like PSL and TSL. Even though other luminescent ions (U 4+ and Eu 3+) are present in the system and U 4+/U 3+ ions are participating in electron capture/release processes, the selective energy transfer results in Tb 3+ ions acting as luminescence centers.
Published Version
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