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

Abstract

Organized molecular films of rare earth β-diketone complexes REL 3Phen 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 β-diketone ligands acac (acetylacetone), TFA(trifluoroacetylacetone), HFA (hexafluoroacetylacetone) and TTA (thenoyltrifluoroacetone); Phen denotes the organic synergistic ligand 1,10-phenanthroline. The fluorescence lifetime of the rare earth β-diketone complexes in LB films was measured by the laser-induced fluorescence decay. The influence of β-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 β-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 β-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.