Knowledge Bank

The environment has a pronounced effect upon the emission spectra and the fluorescence lifetimes of $Sm3+$ in $POCl3:SnCl4$ whereas its effect upon the absorption spectra is less marked. At constant concentration of $Sm3+$ both the fluorescence lifetimes of $Sm3+$ and the fluorescence efficiency increase as the ratio $[POCl3]/[SnCl4]$ decreases. Maximum lifetimes obtained at low $[Sm3+]$ approach a limiting vlaue of 3.31 msec. On the other hand maximum fluorescence efficiency is attained at an optimum ratio of 89:11. Fluorescence and absorption spectra of $Sm3+$ in $POCl3:ZrCl4$ exhibit similar dependence upon the environment. The fluorescence efficiency of $Sm3+$ in the aforementioned solvents is enhanced considerably at slightly lower temperatures; i.e., it is enhanced by a factor of 3 if the temperature is lowered from $25\circ C$ to $5-10\circ C$. Self-quenching rate constants have been determined via both the fluorescence lifetimes and the fluorescence spectra. This project was supported by Owens-Illinois, Corporate Research Laboratories.