On the Radial Dependence of the Fluorescence-Quenching Interaction between Rare-Earth Ions

The radial dependence of the quenching interaction between rare-earth ions has been studied through observation of the Tb3+ fluorescence lifetime in samples of Gd1–2cTbcHocCl3·6H2O. The probability for a quenching interaction, PInt, has been determined to be PInt∝c2∝1/r6. On the basis of the ``resonance'' transfer of energy, such a radial dependence implies a dipole—dipole interaction. Other experiments are discussed in which identical results are obtained.