MAGNETIC RESONANCE INVESTIGATIONS OF LaCl 3 :Ce 3+ SCINTILLATORS.

In undoped and Ce 3+ -doped LaCl 3 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 LaCl 3 . No EPR signals of V K centres (self-trapped holes) could be detected in undoped or Ce 3+ -doped LaCl 3 after X-irradiation at low temperatures. X-irradiation of undoped LaCl 3 creates also an EPR spectrum which can be tentatively attributed to F-type defects. The scintillation mechanism is discussed. [ABSTRACT FROM AUTHOR]