Abstract
It has been shown recently that the fluorescence efficiency of Eu3+ in organic solvents is reduced to a different extent by the solvent molecules located in the primary and in the secondary solvation spheres of the ion(1,2). The primary solvation sphere was associated with the nonradiative quenching processes of the rare-earth ion, kh, whereas molecules located in the secondary solvation sphere were associated with a secondary fluorescence quenching effect i.e. ksolv sec or KQ sec. The structure of the primary solvation sphere was found to exert a marked effect upon the fluorescence efficiency and lifetimes of Sm3+ in POCl3: SnCl4 (3). Furthermore, a pronounced effect, due to both the primary and the secondary solvation sphere, was observed upon the intensity and the splitting of absorption and emission bands of Eu3+ associated with electric-quadrupole transitions(4).