Energy transfer in CaCl2:Eu:Mn crystals

An investigation was made of the energy transfer between Eu 2+ and Mn 2+ ions in CaCl 2 single crystals under photoexcitation. The studies performed at several impurity concentrations and the measurements of the excitation spectra and lifetimes of the observed europium and manganese emissions in the temperature range 11-300 K suggest that the Eu 2+ to Mn 2+ energy transfer process taking place in the authors slightly doubly doped crystals of CaCl 2 :Eu:Mn occurs in small complexes of Eu-Mn which are formed in the lattice. The spectroscopic data obtained substantiate the ionic radius criterion proposed by Rubio et al. (1988) to predict pairing between two impurity ions in a solid material between which energy transfer is desired.