分析指认固体中稀土离子4f-5d跃迁光谱的简单模型

The Simple Model and Its Application to Interpretation and Assignment of 4f-5d Transition Spectra of Rare Earth Ions in Solids

概要介绍和总结最近由段昌奎等人提出,并经发展扩充的用以分析指认固体中稀土离子f-d跃迁光谱的简单模型,以及对Nd3+、Sm3+、Eu3+、Eu2+、Tb3+、Ho3+、Er3+的f-d激发光谱及Nd3+的d-f辐射谱的成功应用。也论及值得进一步研究的其他离子的f-d谱。

The UV and VUV spectra of RE ions du cently. Extension of the semi-empirical model for f^N e to f-d transition have attracted considerable interest reconfiguration to f^N-1d configuration has been very successful in simulation of the spectra. However, it generally needs about 30 parameter values and produces many closing-by eigenstates with strong mixing of quantum numbers S, L and J, which makes the results difficult to interpret. On the other hand, as a result of the strong coupling between 5d orbitals and host lattice, the observed spectra contain mainly broad bands, with most fine structures due to 4f crystal-field interaction etc. washed out. Therefore a simplified theoretical description of the spectra is feasible and useful. In 2002 - 2003, Duan and co-workers proposed a simple model for f-d transition, which was extended to a more applicable form later. In the model, H50（d） and Hcf（f） are ignored, and Hcoul（fd） and H50（f） are approximated to be H^exfd = -JexSf· Sd and H＇50（f） = ληsρLfSf·Lf, respectively, so that the main energy splitring △Ei of f^N- 1 d configuration involves only Jex and ληsρLfSf·Lf, and the relative line strength Ii of f-d transition is expressed with relevant angular momentum quantum numbers. By using beth of △Ei and Ii, the f-d excitation spectra of Sm^3＋ , Eu^2＋ and the d-f emission spectrum of Nd^3＋ in solids are interpreted well in Refs. [7,8], so are the f-d excitation spectra of Nd^3＋ , Eu^3＋ and Tb^3 ＋ doped in solids elsewhere. For heavy RE ions the effect of H50（f） is stronger than that of Hex（fd）. By interchanging the coupling order of relevant angular momenta and considering the effect of H50 （f） more accurately, the simple model has been extended and reconstructed to suit this case. It has been successfully applied to Er^3＋ and Ho^3＋ Application of the simple model and its extension turns out to be less successful for Pr^3 ＋ and Tm^3＋ , which is worth further investigating, while the detailed application to Dy^3＋ （containing contributions from non-diagonal elements） has been working on.