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

Abstract

Photoacoustic (PA) spectra of Eu(TTA) 3·Phen and Eu 0.8Gd 0.2(TTA) 3·Phen (TTA: thenoyltrifluoroacetone; Phen: phenanthroline) complex powders and their doped silica gels are reported. The PA absorption of the ligand of Eu(TTA) 3·Phen is stronger than that of Eu 0.8Gd 0.2(TTA) 3·Phen for complex powders. For the PA intensity of the complexes in silica gels, the reverse is true. This indicates that the addition of Gd 3+ ion changes the relaxation processes of the europium ternary complex and that the relaxation processes of ternary complexes are different in the two kinds of solid state. The changes of the fluorescence spectra turn out to be complementary to the PA spectra. Eu 0.8Gd 0.2(TTA) 3·Phen was prepared by coprecipitation, the luminescence of Eu 3+ is enhanced by an intermolecular energy transfer process. In the silica gel doped with Eu 0.8Gd 0.2(TTA) 3·Phen, complex molecules are trapped in the pores and isolated from each other. The fluorescence intensity of Eu 3+ decreases with the replacement of Eu 3+ by Gd 3+ ion.