Photoacoustic spectroscopy study on the co-fluorescence effect of Eu3+–La3+–Hba solid complexes Original Research Article

The photoacoustic (PA) spectra of Eu3+–La3+–Hba complexes are reported (Hba: benzoic acid). It is found that the PA intensity of the ligand bears a relation to the energy transfer processes. For Eu3+–La3+–Hba coprecipitates, with increasing the concentration of La3+, the PA intensity in the region of the ligand absorption decreases firstly, then increases. It is indicated that the addition of the second rare earth ion La3+–changes the relaxation processes of the complexes. The changes of fluorescence spectra turn out to be complementary to the PA spectra. The intramolecular energy transfer and intermolecular energy transfer processes in the coprecipitates are discussed.