Influence of the anion on the spectroscopy and scintillation mechanism in pure and Ce3+-doped K2LaX5 and LaX3 (X=Cl, Br, I)

The optical properties and scintillation mechanism in pure and Ce 31 -doped K2LaX5 and LaX3 have been determined under x-ray, g-ray, vacuum ultraviolet light, and synchrotron radiation excitation. Special attention is paid to the influence of anions X5Cl 2 ,B r 2 , and I 2 , and a comparison is made with properties of pure and Eu 21 -doped KX compounds. The energies of the 5d excited states of Ce 31 have been determined, and the total crystal field splitting and the centroid shift are discussed. An excitation across the band gap creates a combination of self-trapped exciton ~STE! and Ce 31 emission. These emissions are often anticorrelated when temperature or Ce 31 concentration is changed. Their ratio is related to the STE mobility and STE creation rate. Clear trends in the optical properties and scintillation mechanism are observed along the halide series.

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