The sensitized fluorescence oi binary and ternary complexes of RE(Eu

Tb)has been studied by the Fluorescence Titration Method

the sensitizers used being mainly β-diketones and aromatic amines.Rare earth europium and terbium

each has its own characteristic fluorescence spectra (Em). With the change of the ligands constituting the complexes

the position of the Em peaks of the RE ions remains basically unchanged whereas their intensities and shapes show some variation.The Eu complexes have two distinct fluorescence peaks in general

corresponding to electric dipole transition(ED)of 610 nm and magnetic dipole transition (MD) of 587 nm.The ratio MD/ED reflects the symmetry of the environment of the RE ions (the smaller the ratio

the less the symmetry).The MD/ED of Eu-|S-diketones complex has been deter-dmined≈0.125

and the MD/ED of Eu-o-phenanthrolein or Eu-2.2'dipyri-dine complex≈0.5.The symmetry of the former is less than that of the latter. The closeness of the MD/ED ratio of the complexes of the same kind means that they have the similarity in the numbers of the ligands cholating on RE ion

their occupation position and the structure of chelates.The spectra of excitation(Ex) of the RE complexes are also related to the kind of ligands. The Ex shapes of Eu-β-diketone complexes are similar each other

they have two peaks

one strong and one weak.More difference exists in the case of Eu-aro-matic amine complexes

but their common point is that each of them has three peaks.The Ex between different kind of complexes are still more different.The above phenomena also reflect that the structure and property of the chelating ligand function group linking RE ion are directly related to the fluorescence spectra of the complexes.