To study intermolecular energy transfer of rare earth-β-diketones, monolayers of miXed RE(TTA)3Phen (RE=La, Gd, Tb, or Y) with Eu(TTA)3Phn iu molar ratio of 1:1 and 1:4 were fabricated in this paper. Meanwhile, an active enhanced spherc model was proposed to acquire the efficient radii of energy transfer between the molecules of complexes. The efficient radius for energy transfer from Gd(TTA)3Phen or Tb(TTA)3Phen to Eu(TTA)3Phen is 12A and thosc from La (TTA)3Phen and Y(TTA)3Phen to Eu(TTA)3Phen are 7A and 10A, respectively. The reliabil-ity of the model was proved by comparing the emission intelisities that were calculated by using values of R mentioned above with experimental values. The model proposed is a supplement to Perrins active sphere theory. By this model a triplet-triplct energy trarsfer can be deduced from TTA of RE(TTA)3Phen to that of Eu(TTA)3Phen. The proccss proceeds by an electron exchange mechamism.
