Fluorescence lifetime and energy transfer of rare earth β-diketone complexes in organized molecular films

Organized molecular films of rare earth beta-diketone complexes REL(3)Phen were fabricated in this paper by the Langmuir-Blodgett film (LB) technology, where RE denotes rare earth ions Eu(III), Sm(III) and Tb(III); L denotes the organic beta-diketone ligands acac (acetylacetone), TFA(trifluoroacetylacetone), HFA (hexafluoroacetylacetone) and TTA (thenoyltrifluoloacetone); Phen denotes the organic synergistic ligand 1,10-phenanthroline. The fluorescence lifetime of the rare earth beta-diketone complexes in LB films was measured by the laser-induced fluorescence decay. The influence of beta-diketone ligands on the fluorescence intensity of rare earth complexes was discussed in view of the intramolecular energy transfer process. The fluorescence lifetime of the rare earth beta-diketone complexes in LB film was longer than that in solution. The difference was investigated in view of the intermolecular energy transfer process. Both the fluorescence lifetime and the fluorescence intensity varied with the beta-diketone ligands of the rare earth complexes. However, their values did not change in the same sequence, which was discussed in view of the different intramolecular energy transfer processes. (C) 2000 Elsevier Science S.A. All rights reserved.