U. Rogulis, S. Schweizer, J.-M. Spaeth, E. V. D. van Loef, P. Dorenbos, C. W. E. van Eijk, K. Krämer and H. U. Güdel
Magnetic Resonance Investigations of LaCl₃:Ce³⁺ Scintillators
Radiation Effects and Defects in Solids 157, 951-955 (2002)                 

Abstract: In undoped and Ce³⁺-doped LaCl₃ EPR has been detected in the X-ray luminescence (XL-EPR) in K-band (25 GHz) at 1.5 K. Two excited triplet states with different EPR parameters and spectral shapes could be separated, both triplet states have been attributed to "out-of-plane" self-trapped excitons (STE) in LaCl₃. No EPR signals of V_K centres (self-trapped holes) could be detected in undoped or Ce³⁺-doped LaCl₃ after X-irradiation at low temperatures. X-irradiation of undoped LaCl₃ creates also an EPR spectrum which can be tentatively attributed to F-type defects. The scintillation mechanism is discussed.