Photoacoustic study of the co-fluorescence effect of lanthanide ternary complexes in solid states

Photoacoustic (PA) spectra of Eu(TTA)(3).Phen and Eu0.8Gd0.2(TTA)(3).Phen ( TTA: thenoyltrifluoroacetone; Phen: phenanthroline) complex powders and the ir doped silica gels are reported. The PA absorption of the ligand of Eu(TT A)(3).Phen is stronger than that of Eu0.8Gd0.2(TTA)(3).Phen for complex pow ders. For the PA intensity of the complexes in silica gels, the reverse is true. This indicates that the addition of Gd3+ ion changes the relaxation p rocesses of the europium ternary complex and that the relaxation processes of ternary complexes are different in the two kinds of solid state. The cha nges of the fluorescence spectra turn out to be complementary to the PA spe ctra. Eu0.8Gd0.2(TTA)(3).Phen was prepared by coprecipitation, the luminesc ence of EU3+ is enhanced by an intermolecular energy transfer process. In t he silica gel doped with Eu0.8Gd0.2(TTA)(3).Phen, complex molecules are tra pped in the pores and isolated from each other. The fluorescence intensity of EU3+ decreases with the replacement of Eu3+ by Gd3+ ion. (C) 2000 Elsevi er Science B.V. All rights reserved.