高等学校化学学报 ›› 2021, Vol. 42 ›› Issue (7): 2197.doi: 10.7503/cjcu20210130

• 研究论文 • 上一篇    下一篇

理论研究晶体场效应和电荷转移效应对Co2+2p电子X射线L2,3吸收边光谱的影响

程效1,2,BORA Debajeet K.2GLANS Per⁃Anders2,GUO Jinghua2,罗毅1   

  1. 1.中国科学技术大学合肥微尺度物质科学国家研究中心, 合肥 230026
    2.Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA
  • 收稿日期:2021-03-01 出版日期:2021-07-10 发布日期:2021-06-18

An In-depth Theoretical Study of Ligand Field and Charge Transfer Effects on Co2+2pL2,3-edges X-ray Absorption Spectra

CHENG Xiao1,2, BORA Debajeet K.2, GLANS Per⁃Anders2, GUO Jinghua2, LUO Yi1()   

  1. 1.Hefei National Laboratory for Physical Sciences at the Microscale,University of Science & Technology of China,Hefei 230026,China
    2.Advanced Light Source,Lawrence Berkeley National Laboratory,Berkeley CA 94720,USA
  • Received:2021-03-01 Online:2021-07-10 Published:2021-06-18
  • Contact: LUO Yi E-mail:yiluo@ustc.edu.cn

摘要:

运用多重态计算方法研究了在正八面体对称性的晶体场中Co2+离子的2p电子X射线L2,3吸收边光谱, 研究了Co2+离子和周围的配位离子之间的正八面体(Oh)晶体场效应和相应的电荷转移效应对于吸收光谱的影响. 系统讨论了在多重态计算中起作用的所有物理参数对CoO和CoCl2的X射线吸收光谱特性的特定影响及其物理机制. 将计算得出的光谱数据和同样具有Oh对称性结构Co2+离子的CoO和CoCl2实验光谱数据进行了对比, 在实验光谱数据中发现的特征被确定为来自不同自旋态, 并且光谱强度的变化与晶体场的强度相关, 揭示了其中包含的电荷转移效应. 本文为低对称性复杂系统的多重态计算提供了一个基础的参考标准, 可以适用于含有钴元素或其它过渡金属的复杂体系的X射线吸收光谱的理论计算.

关键词: 多重态计算, X射线吸收光谱, 钴元素, 晶体场效应, 电荷转移效应

Abstract:

The 2p L2,3-edges X-ray absorption spectrum of Co2+ in octahedral(Oh) symmetric ligand field is studied theoretically via the multiplet calculation method. The octahedral symmetric crystal field and corresponding charge transfer effect between ligands and Co2+ cation have been investigated. All the parameters used in the multiplet calculation are discussed systematically in regards to their specific effect on X-ray absorption features and related mechanisms. The calculated results are compared with the L-edge X-ray absorption spectra of CoO and CoCl2, both with the same Oh symmetrical local structure of the Co2+ cation. The experimentally observed multiplet spectra features are assigned to different spin states and their intensity change is rela-ted to the crystal field strength. The underlying charge transfer effect has also been revealed. This study provides a fundamental basis for multiplet calculations of complex systems with lower symmetry associated with cobalt and other transition metals.

Key words: Multiplet calculation, X-ray absorption spectrum, Cobalt, Crystal field effect, Charge transfer effect

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