A study was made of mutual interaction, and electronic-vibrational energy transfer processes, between divalent Sm ions and neighboring CN- molecular impurities. This was done by using the highly site-selective technique of combined excitation-emission spectroscopy and vibrational CN- luminescence. It was found, for Sm2+-CN- complexes (involving just a single CN- molecule), that the spectral shifts of the intra-configurational (4f <--> 4f) transitions were very small. They were some 10 times larger for the inter-configurational (4f6 <--> 4f55d1) transitions. No measurable energy transfer from the electronic excitation, to the vibrational CN- stretching mode, occurred for those centers. This reflected the weakly interactive nature of the energetically lowest excited 5D0 state which belonged to the 4f-electronic configuration. For more complex centers, which appeared at higher CN- concentrations and involved more than one CN- molecule, the more strongly coupled 5d-type states were shifted to lower energy; even below the 5D0 state. In this case, E-V energy transfer could be detected by the appearance of vibrational luminescence.

Interaction and Energy Transfer between Divalent Sm Ions and CN- Molecular Defects in KCl. V.Dierolf: Physical Review B, 1999, 60[18], 12601–9