钇镓石榴石中Tb3+到Ce3+的无辐射能量传递特征

在Y₃Ga₅O₁₂石榴石中,室温下采用紫外激光选择激发光谱研究了能量从Tb³⁺的⁵D₃和⁵D₄能级无辐射传递给Ce³⁺的²D_3/2能级。实验结果符合Frster-IH直接无辐射传递理论。⁵D₃(Tb³⁺)→²D_3/2(Ce³⁺)能量传递是电偶-偶极子相互作用机理,其平均临界传递距离为R₀=16.3?,而⁵D₄(Tb³⁺)→²D_3/2能量传递是起主导作用的电偶-偶极子相互作用,其平均临界传递距离为11.2?。在⁵D₄的传递过程中,电偶-四极子相互作用也应予以考虑。 关键词：

TRANSFER CHARACTERISTICS OF NONRADIATIVE ENERGY FROM Tb3+ TO Ce3+ IN YTTRIUM GALLIUM GARNETS

Selection-excited spectra and fluorescence lifetimes of Tb³⁺ and Ce³⁺ ions in yttrium gallium garnets are obtained at room temperature. In Y₃Ga₅O₁₂:Tb, Ce, Tb³⁺ (donor) emission spectrum and Ce³⁺( acceptor) excitation spectrum overlaps considerably. The observed fluorescence lifetimes of Tb^{3+ 5}D₃ and ⁵D₄ levels decrease with Ce³⁺ concentration when the sample of Y₃Ga₅O₁₂: Tb, Ce are excited by UV laser pulse. The mechanisms for nonradiative energy transfer from ⁵D₃ and ⁵D₄ states of Tb³⁺ to ²D_3/2 state of Ce³⁺ are found to be electric dipole-dipole interaction. The critical distance, rate and efficiency of energy transfer from Tb³⁺ to Ce³⁺ ion are obtained. The average critical transfer distance (R₀) for ⁵D₃ and ⁵D₄(Tb³⁺)→²D_3/2(Ce³⁺) are 16.3 ? and 11.2 ?, respectively. Although the energy transfer from the ⁵D₄ state is dominated by dipole-dipole interaction, the dipole-quadrupole interaction must also be considered.
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