Excited state dynamics and energy transfer rates in Sr_3Tb_(0.90)Eu_(0.10)(PO_4)_3

摘要

The emission spectrum of neat Sr_3Tb(PO_4)_3 upon excitation at 337 nm in the levels above ~5D_3 is dominated by ~5D_4 emission and no significant emission from ~5D_3 is observed due to efficient cross relaxation involving the Tb~3 levels. On the other hand, the emission spectrum of the same host containing 10 mol Eu~3 upon excitation at the same wavelength (in the Tb~3 levels) is dominated by strong emission bands from the ~5D_0 level of Eu~3. This clearly indicates that Tb~3→Eu~3 energy transfer is present. The excitation spectrum of the Eu~(35)D_0 emission is dominated by Tb~3 bands extending in the UV region. The presence of 10 mol Eu~3 in Sr_3Tb(PO_4)_3 very strongly shortens the ~5D_4 decay time. The decay curve is not far from exponential, indicating that the energy transfer to Eu~3 is accompanied by fast energy migration. The transfer regimes are identified and the donordonor and donoracceptor transfer microparameters are quantified under the assumption of electric dipoleelectric dipole interactions.