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

Abstract

The optical properties and scintillation mechanism in pure and Ce3+-doped K2LaX5 and LaX3 have been determined under x-ray, γ-ray, vacuum ultraviolet light, and synchrotron radiation excitation. Special attention is paid to the influence of anions X=Cl-, Br-, and I-, and a comparison is made with properties of pure and Eu2+-doped KX compounds. The energies of the 5d excited states of Ce3+ 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 Ce3+ emission. These emissions are often anticorrelated when temperature or Ce3+ 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. © 2003 The American Physical Society.