STUDY ON SYNERGISTIC LUMINESCENCE EFFECT AND ITS LUMINESCENCE MECHANISM
Hu Jiming Chen Guanquan(Department od Analysis-Measurement Science, Wuhan University, Wuhan 430072)Zeng Yun'e(Department of Chemistry, Wuhan University, Wuhan 430072)
A new sensitized fluorescence phenomenon was observed by adding some of metal ions to europium, samarium-dibenzoylmethane-cetylpyridium bromide(Eu, Sm-DBM-CPB)or europium, samarium-lhenoyltrifluoroacetone-1, 10-phenanthroline-Triton X-100 (Eu, Sm-TTA-Phen-TX-100) systems, which is named as a synergistic luminescence effect. The synergistic luminescence effect and its luminescent mechanism were studied using laser--induced fluorimetry.The influence of the chemical properties of rare earth ions on the synergistic luminescence effects of above systems is reported. In general, the synergistic luminescence effect is enhanced with the increase of ionic radius of synergistic ions. The systems exhibit similar fluorescence characteristics in the presence of different synergistic ions.From the experimental results, a mechanism of synergistic luminescence is proposed. The following factors affect the synergistic luminescence.1. Synergistic ions do not form new chelates with luminescent ion chelates. The solid solution is formed between luminescent ion chelates and synergistic ion chelates.2. Synergistic luminescence effect is influnced by the structure and symmetry of the chelates of luminescent ion and synergistic ion. 3. All the synergistic ions which have enhanced effect, except terbium, dysprosium and ytterbium, possess 8 stable outer electronic orbit. The synergistic luminescence effects of terbium,dysprosium and ytterbium ions can be explained by the valence fluctuation between the synergistic ions and ligands.The excitation energy transfer plays an important part in the energy transfer of synergistic luminescence effect.The proposed method can be used for determination of trace amounts of europium and samarium. Results are satisfactory for the determination of trace europium and samarium in highly pure rare earth oxides and synthetic samples without pre-separation.