Cr3+∶MgAl2O4晶体的基态能级分裂及Jahn-Teller效应*

构造了3d3/3d7离子在三角对称晶场中考虑自旋-轨道相互作用,自旋-自旋相互作用和自旋-其它轨道相互作用的120阶微扰哈密顿矩阵.利用完全对角化该矩阵的方法计算了Cr3+∶MgAl2O4晶体的基态能级、零场分裂参量,理论计算值与实验值相符合.定量研究了自旋二重态对基态能级的贡献,证明该贡献是不可忽略的.定量研究了自旋-轨道相互作用、自旋-自旋相互作用和自旋-其它轨道相互作用对Cr3+∶MgAl2O4晶体的光谱精细结构和零场分裂参量的影响,发现自旋-轨道和自旋-自旋相互作用对基态能级和零场分裂参量的影响的程度和方式是不同的,自旋-其它轨道相互作用的影响也是不可忽略的.通过理论计算值和实验值的比较,证实了在Cr3+∶MgAl2O4晶体中Jahn-Teller效应的存在,解释了该晶体的光谱精细结构的成因.

Energy Level Splitting of Ground-state and Jahn-Teller Effects in Cr3+ : MgAl2O4 Crystal

The Hamiltonian matrixes of order 120 of 3d3/3d7 ions configuration in the trigonal symmetry have been established, taking into account spin-orbit interaction, spin-spin interaction and spin-other-orbit interaction. Ground-state energy levels, zero-field splitting parameter of Cr3+∶ MgAl2O4 crystal were calculated by using completely diagonalized the matrixes method, the values of theoretical calculation conform with the experiments. The contributions of spin doublets for the ground-state energy levels were studied. The results show that the contributions can not be neglected. The influences of spin-orbit interaction, spin-spin interaction and spin-other-orbit interaction on the fine structure of spectra and zero-field splitting parameter of Cr3+∶ MgAl2O4 crystal were studied quantitatively. It is found that the influences of spin-orbit interaction and spin-spin interaction on the ground-state energy levels and the zero-field splitting parameter are different in degree and mode, and the influence of spin-other-orbit interaction can not be neglected too. By comparing the values of theoretical calculation with the experiments, the existence of Jahn-Teller effects in the Cr3+∶ MgAl2O4 crystal is confirmed and this can give more reasonable explain on the genesis of fine structure of spectra.