Interaction and energy transfer between divalent Sm ions and CN- molecular defects in KCl

We studied the mutual interaction and electronic-vibrational energy transfer processes between divalent samarium ions and neighboring CN- molecular impurities in KCl by the highly site-selective technique combined excitation-emission spectroscopy as well as by vibrational CN- luminescence (VL). We found for combined excitation-emission spectroscopy as well as by vibrational CN- luminescence (VL). We found for Sm2+ -CN- complexes involving just a single CN- molecule that the spectral shifts of the intraconfigurational (4f <-> 4f) transitions are very small, and are about 10 times bigger for the interconfigurational (4f(6) <-> 4f(5)5d(1)) transitions. No measurable energy transfer from the electronic excitation into the vibrational CN- stretch mode takes place for those centers, reflecting the weakly interacting character of the energetically lowest excited D-5(0) state which belongs to the 4f-electronic configuration. However, for more complex centers which appear for higher CN- concentrations and involve more than one CN- molecule the more strongly coupled 5d-type states are shifted to lower energy, even below the D-5(0) state. In this case E-V energy transfer can be observed by the appearance of VL. [S0163-1829(99)07941-2].