Energy transfer processes from Tb3+ to Eu3+ in ternary chelate doped in gel glasses via in situ technique

Rare earth ternary chelates Ln(TFA)3(TPPO)2 (Ln = Eu, Tb and Eu/Tb) were synthesized in gel glasses via in situ technique. Pure Ln(TFA)3(TPPO)2 chelates were also synthesized for a comparative study. Photoluminescence properties of the in situ chelates in gel glasses and the pure chelates were studied. In order to investigate the energy transfer mechanism from Tb3+ ions to Eu3+ ions in Eu/Tb(TFA)3(TPPO)2 chelates, photoluminescence spectra and fluorescence decay curves have been measured at the temperature range from 10 K to 293 K. It is found that the energy transfer rate constants calculated from the fluorescence lifetimes do not vary with temperature, which suggests that Dexter mechanism is responsible for the energy transfer from Tb3+ ions to Eu3+ ions in both pure and in situ Eu/Tb ternary chelate.