Crystals of the complexes of Tryptophan with Sm(III), Tb(III) and Dy(I
II) were synthesized and the photoacoustic (PA) spectra in the UV-vis
region were recorded. The PA intensities of the central lanthanide ion
s are interpreted in terms of the probability of nonradiative transiti
ons. It is found that the PA intensity of the ligand bears a relation
to the intramolecular energy transfer process. For the title complexes
, the different PA intensities of the ligand, tryptophan, are interpre
ted by comparison with the fluorescence spectra. The relaxation proces
s models are also studied based on the PA and fluorescence spectra. (C
) 1998 Elsevier Science B.V. All rights reserved.