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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Er3+离子的低局域对称性对ErFe3(BO3)4单晶磁圆二色性和ff跃迁吸收光谱的影响


在90 K、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性(MCD)光谱。ff跃迁的吸收光谱被分解为洛伦兹形状分量和发现了组分的强度。 MCD 光谱使我们能够测量某些跃迁的塞曼分裂，从而确定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 跃迁的光学和磁光性质与 ErAl3(BO3)4 晶体中的光学和磁光性质进行了比较。揭示了两种晶体中与 Er3+ 离子局域对称性差异相关的性质的显着差异。观察到在没有磁场的情况下 ff 跃迁之一发生大分裂，这对于克莱默双峰来说是不可能的。这是由于激发态对称性局部降低而出现两个吸收中心来解释的。揭示了一些激发态下局部振动能量的显着差异。