Thermal dependence of impurity induced fluorescence in the system RbMgxMn1-xF3

The absorption spectrum of RbMnF₃ and the excitation spectra of the system RbMg_xMn_1-xF₃ at 10 K as well as the fluorescence spectra and lifetimes of Mn²⁺ in the systems RbMg_xMn_1-xF₃ and KMg_xMn_1-xF₃ in the region 10–300 K were measured. The lifetime and fluorescence temperature dependence suggest that the origin of the fluorescence occurs at Mn²⁺ sites slightly perturbed by impurity ions and that a non-radiative energy transfer mechanism is responsible for the observed thermal quenching. By using different Mn²⁺ concentrations in the above systems the dependence of the energy transfer on the Mn²⁺ concentration is shown. Finally, a preliminary observation on laser stimulated Mn²⁺ luminescence in the system RbMg_xMn_1-xF₃ is reported.