Energy transfer phenomena in the luminescence of wide band‐gap scintillators

Abstract

Luminescence and scintillation dynamics can be extensively influenced by the energy transfer processes, which is demonstrated at three selected scintillator materials: PbWO 4 , Ce-doped aluminium garnets and PrF 3 : Ce single crystals. Charge carrier retrapping processes can delay radiative recombination at the luminescence centers in an extended time scale, which makes a substantial part of generated scintillation light technically unexploitable. Correlated measurements based on time-resolved emission spectroscopy and thermoluminescence are of great help to evaluate these phenomena and to understand their microscopic origin.

Luminescence of dimer lead centers in aluminium perovskites and garnets

“…The presence of such defects in the garnet and perovskite structures was predicted also by theoretical calculations [9][10][11][12] and the ability of such defects to create shallow electron traps was recently theoretically examined in YAP [13]. As this intrinsic emission is overlapped with the Ce 3+ absorption bands, the scintillation response of the Ce 3+ -doped materials can be negatively affected due to the appearance of a considerable amount of slow decay components [5,14].…”

Luminescence and scintillation characteristics of YAG:Ce single crystalline films and single crystals

“…In the latter sample the N phels LY increases in the 0.5-10 ms time range by about of 8.5% while for YAG:Ce SCF this value is at least two time lower (w4.2%). The latter observation points to lower content of shallow electron traps in the YAG:Ce SCF with respect to YAG:Ce SC due to absence of the ADs as trapping centers in SCF scintillators Nikl, 2005). Thus, the PbO-based flux can be successfully applied for producing the YAG:Ce SCF scintillators with comparable or even better scintillation properties than those of the SC analogues.…”

“…The Y Al and Lu Al ADs in YAG:Ce and LuAG:Ce SC play the role of emission centers in UV range (Zorenko et al, 2007a) and trapping centers . These centers participate in the excitation of the Ce 3þ luminescence and are responsible for large amount of slow components in scintillation decay of YAG:Ce and LuAG:Ce SCs (Nikl, 2005;Zorenko et al, 2007b). Due to low temperature of growth by the liquid phase epitaxy (LPE) method, the YAG:Ce and LuAG:Ce SCFs can in principle possess better scintillation properties as compared with the corresponding SC due to the absence of Y Al or Lu Al ADs.…”

Электронные ловушки в Gd-=SUB=-3-=/SUB=-Ga-=SUB=-3-=/SUB=-Al-=SUB=-2-=/SUB=-O-=SUB=-12-=/SUB=-:Ce-гранатах, активированных редкоземельными ионами

“…В частности, кера-мика Gd 3 Ga 3 Al 2 O 12 : Ce 3+ (GGAG : Ce) обладает хорошей сцинтил-ляционной эффективностью 70000 photons/MeV и высокой плотно-стью 6.63 g/cm 3 [5]. Однако время спада сцинтилляций (τ = 143 ns) керамики GGAG : Ce значительно больше, чем соответствующее время (∼ 50 ns) при непосредственном возбуждении иона Ce 3+ (фотолюми-несценция) [6]. Причиной увеличения времени спада является наличие дефектов, которые могут создавать дополнительные энергетические…”