The clusters of Eu^(3+) ion in Eu(DBM)3Phen-doped polymethyl methacrylate (PMMA) have been studied by three means. The relative fluorescence intensity ratio of the 5D0 -> 7F2 to 5D0 -> 7F1 transitions with different concentrations of Eu^(3+) in Eu(DBM)3Phen-doped PMMA and metastable-state (5D0)