稀土离子发光体系中能量传递和迁移模型的研究

基于以前综合V-F模型(考虑施主受主(D-A)能量传递)和B模型(考虑施主施主(D-D)能量迁移)而提出的V-F-B综合模型,对La_1-xEr_xF₃体系中Er³⁺离子四种低掺杂浓度下(x=0.001,0.003,0.01,0.02)295K时⁴S_3/2→⁴I_15/2发光的时间演化曲线成功地重新进行了数值拟合.结果表明该体系内D-A间交叉弛豫能量传递是偶极-偶极作用,作用常数C_DA为4.75×10^-41cm⁶/s,与Okamoto等人原用YT扩散模型得到的结果一致.而拟合得到的四个D-D平均跳跃时间τ₀粗略地与x_D^α次方(x_D为D离子浓度)成正比(α≈-1.237),并不遵从τ₀很小时与x_D的-2次方成正比的理论关系.同时,通过把D-D迁移和D-A传递同时同样地纳入V-F模型还粗略估计了D-D平均跳跃时间τ₀′的值,发现它与V-F-B给出的τ₀拟合值比较一致,说明V-F-B模型在一定近似程度上是内部自恰的、合理的. 关键词： 能量传递 能量迁移 跳跃时间 交叉弛豫

A STUDY ON ENERGY TRANSFER AND ENERGY MIGRATION MODELS FOR RE IONS LUMINESCENCE SYSTEM

By Application of the V-F-B model which is obtained by combining the Vasquez-Flint (V-F) model for donor-acceptor energy transfer and the model of Burshtein for donor-donor energy migration, the experimental luminescence decay curves of ４S3／2 state of Er3+ in LaF3 at 295K for four different concentrations are re-simulated successfully.It is found that in this system the donor-acceptor interaction is dipole-dipole interaction,and that the donor-acceptor interaction constant CDA is 4.75×10-41 cm6/s. The results are all in agreement with the previous results of Okamoto. However, the hopping time τ0 obtained from the above simulation in proportional to xＤ-1.237 (xD is the donor concentration), which is different from the theoretical dependence on the donor concentration (that is τ0 ∝ xD-2). In addition, by considering donor-acceptor energy transfer and donor-donor energy migration within the V-F model at the same time, we obtain the estimated values of the hopping time τ0′ for four different concentrations, which are in reasonable agreement with the values of τ0 obtained from the above simulation.It seems that the V-F-B model is rather self-consistent.