Linearly polarized absorption spectra and magnetic circular dichroism (MCD) spectra of ErFe3(BO3)4 single crystal were measured in the range of 9000–23000 cm−1 at 90 K. The absorption spectra of f-f transitions were decomposed into the Lorentz shape components and intensities of the components were found. MCD spectra permitted us to measure the Zeeman splitting of some transitions and so to determine changes of the Landé factor along the C3 axis of the crystal during these transitions. Optical and magneto-optical properties of f-f transitions in the ErFe3(BO3)4 crystal were compared with those in the ErAl3(BO3)4 crystal. Substantial difference of the properties connected with the difference of the Er3+ ions local symmetry in two crystals was revealed. Large splitting of one of the f-f transitions without magnetic field, which is not possible for the Kramers doublets, was observed. It was explained by appearance of two absorbing centers due to the local decrease of symmetry in the excited state. Appreciable difference of the local vibrations energy in some excited states was revealed.

中文翻译：

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Er 3+ 离子的低局域对称性对ErFe 3 (BO 3 ) 4 单晶磁圆二色性和ff跃迁吸收光谱的影响

摘要 在 90 K 下在 9000-23000 cm-1 范围内测量了 ErFe3(BO3)4 单晶的线偏振吸收光谱和磁圆二色 (MCD) 光谱。ff 跃迁的吸收光谱被分解为洛伦兹形状分量和强度的成分被发现。MCD 光谱使我们能够测量某些跃迁的塞曼分裂，从而确定在这些跃迁期间朗德因子沿晶体 C3 轴的变化。将 ErFe3(BO3)4 晶体中 ff 跃迁的光学和磁光特性与 ErAl3(BO3)4 晶体中的那些进行了比较。揭示了与两种晶体中 Er3+ 离子局部对称性差异相关的性质的显着差异。没有磁场的 ff 跃迁之一的大分裂，观察到这对于 Kramers 双峰来说是不可能的。这可以通过由于激发态对称性的局部降低而出现两个吸收中心来解释。揭示了一些激发态的局部振动能量的明显差异。