Energy transfer mechanism in CsI: Eu crystal

This paper studies the scintillation process in CsI:Eu crystal exposed to the pulse electron irradiation (E=0.25 MeV, t_1/2=15 ns and W=0.003 J/cm²). It has been proved that the energy transfer from the lattice to Eu²⁺ ions in CsI:Eu occurs through the re-absorption of STE emission. The proposed model rests on the following experimental facts: (1) the activator emission at 2.68 eV rises gradually after the decay of the excitation pulse even at temperature lower than 90 K when V_k centers are immobile; (2) the rise time of 2.68 eV emission and the decay time of STE emission have the same temperature dependences at T=78-300 K; (3) the excitation spectrum of 2.68 eV emission overlaps the emission spectrum of STE.