Luminescence properties and scintillation mechanisms of cerium- and praseodymium-doped lutetium orthoaluminate

Absorption, reflection as well as luminescence emission, excitation, and decay curves for single crystals of LuAlO3:Ce3+ and LuAlO3:Pr3+ grown by the Bridgman technique have been measured at various temperatures. The fluorescence spectra photo-excited over a wide energy domain ranging from the UV to the x-ray region, and the kinetics are typical of the cerium and praseodymium ions. These experimental results show that the exciton transfer to the dopant occurs at around 8 eV, and the energy transfer via sequential hole and electron trapping is dominant at higher energy. This process must be considered as the main scintillation mechanism in this crystal. The high efficiency of this mechanism is explained by the small energy difference between the 4f level of the dopant and the top of the valence band, estimated from XPS measurements.