Magnetic circular dichroism of symmetry and spin forbidden transitions of high-spin metal ions
Magnetic circular dichroism of symmetry and spin forbidden transitions of high-spin metal ions
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DOI：
10.1063/1.1289531
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发表时间：
2000-09-22
影响因子：
4.4
通讯作者：
Thomson, AJ
中科院分区：
文献类型：
--
作者：
Oganesyan, VS;Thomson, AJ
最近，我们发展了一种分析高自旋金属离子自旋允许跃迁的磁圆二色谱和磁化曲线的通用方法[Oganesyan，J.Chem]。太棒了。110、762(1999)]。在本文中，这一方法被扩展到包括自旋禁忌跃迁和对称禁忌跃迁的情况。在高配位场下，许多低能配位场跃迁成为自旋禁忌。通过分析和关联MCD带的位置、符号和强度以及这些跃迁的磁化曲线，可以获得关于基态电子结构的信息内容。该理论采用不可约张量方法，充分利用了任何对称元素，简化了多电子计算。该理论在整个磁场强度范围内都是有效的，因此，允许在整个磁场和温度范围内利用光谱的信息含量。将该方法应用于热自养甲烷杆菌(MARBURG)红曲霉蛋白(MARBURG)中拟四面体高自旋Fe(III)，S=5/2最低能自旋-禁忌配位场跃迁的磁化曲线和MCD谱的分析。这些相变的信号、强度和磁化曲线与实验数据符合得很好。我们还表明，当基态的各向异性大于塞曼分裂时，自旋禁止跃迁和允许跃迁的MCD在大小上是相似的。因此，为了避免对实验结果的误解，需要谨慎。(C)2000年美国物理研究所。[S0021-9606(00)01236-8]。
Recently we have developed a general method of analyzing magnetic circular dichroism (MCD) spectra and magnetization curves of high-spin metal ions for spin-allowed transitions [Oganesyan , J. Chem. Phys. 110, 762 (1999)]. In the present article this approach is extended to cover the cases of spin- and symmetry-forbidden transitions. At high ligand fields many low-energy ligand field transitions become spin-forbidden. Extraction of information content about the electronic structure of the ground state can be obtained through the analysis and correlation of the positions, signs, and intensities of the MCD bands and magnetization curves of these transitions. The casting of the theory in terms of the irreducible tensor method allows full advantage to be taken of any symmetry elements and simplifies multielectron calculations. The theory is valid over the entire range of magnetic field strength and, therefore, allows the information content of spectra over the full field and temperature range to be exploited. The method is applied to the analysis of the recorded MCD spectra and magnetization curves of the lowest energy spin-forbidden ligand field transitions of pseudo-tetrahedral high-spin Fe(III), S=5/2, in the protein rubredoxin from Methanobacterium thermoautotrophicum (strain Marburg). The predicted signs, intensities, and magnetization curves for these transitions are in excellent agreement with experimental data. We also show that when the anisotropy of the ground state is larger than the Zeeman splitting the MCD of both spin-forbidden and allowed transitions can become comparable in magnitude. Hence caution is needed in order to avoid the misinterpretation of experimental results. (C) 2000 American Institute of Physics. [S0021-9606(00)01236-8].