| 摘 要： | Time-resolved fluorescence spectra of europium methylbenzoates(MBA)with 1,10-phenanthroline(phen)have been measured at room temperature.Foreach of the europium chelates,where the ligand triple states lie above the ~5D_1 level ofEu~(3-),the spectra providc evidence that the Eu~(3-) ~5D_0 state is populated by nonradiativeenergy transfer from the higher-lying ~5D_1,state.The relaxation time for energy decayfrom ~5D_1 state is measured in the microcrystals to bc of the order of a fewmicroseconds.It is suggested that the ligand C=0 and C=C stretching vibrations andEu-O vibrations,chclate ring and benzene ring vibrations make importantcontributions to the relaxation process.The ~5D-1—~5D-0 relaxation time of Eu-(p-MBA)_3phen is shorter than those of Eu(m-MBA)_3phen and Eu(o-MBA)_3phensince nonradiative degradation to ~5D_0 from ~5D_1 appears to be more strongly influencedby the E_u~(3+)sites in the former.
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