An emission and kinetic study of the impurity-trapped exciton in CdCl₂:Pb²⁺

We have studied the spectroscopic properties of Pb²⁺ in a CdCl₂ host crystal. By excitation in the absorption band due to the ¹A_1g to ³T_1u(³P₁) transition, two emission bands are observed. At very low temperature a strong UV luminescence with a very long lifetime (2.5 ms) is detected. As the temperature increases, the lifetime of the UV emission drastically decreases to a few nanoseconds at 100 K, and the UV intensity declines. Meanwhile a strong green fluorescence appears. It is assumed that this emission is of the impurity-trapped exciton type, as in the case of CdCl₂:Cu⁺ and BaF₂:Eu²⁺. A detailed study of the kinetics of both fluorescences is presented.