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化学位移张量的测量

王立英,邓风,叶朝辉*   

  1. 波谱与原子分子物理国家重点实验室 中国科学院武汉物理与数学研究所,湖北 武汉 430 071
  • 收稿日期:2002-04-01 修回日期:2002-06-24 出版日期:2002-12-05 发布日期:2004-12-05
  • 作者简介:王立英(1977-),女,湖北襄阳人,博士研究生,固体核磁共振及其应用专业.*通讯联系人
  • 基金资助:

    国家自然科学基金资助项目(20075034).

MEASUREMENT OF CHEMICAL SHIELDING TENSOR

WANG Li-ying, DENG Feng, YE Chao-hui*   

  1. State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan  Institute of Physics and Mathematics, The Chinese Academy of Sciences, P.O.Box71010, Wuhan 43 0071, China
  • Received:2002-04-01 Revised:2002-06-24 Online:2002-12-05 Published:2004-12-05
  • Supported by:

    国家自然科学基金资助项目(20075034).

摘要:

对于刚性晶格中的分子,化学位移是与外加磁场空间取向相关的张量,这个张量有6个独立的分量. 化学位移张量也可以利用其主轴分量及主轴与晶体坐标系的方向余弦来表示. 很显然,知道了固体分子中各不等价位置处的化学位移张量,就可以推测出分子中电子分布的图象,具有重要意义. 本文首先描述了化学位移张量测量的理论,对测量化学位移 各 向异性的各种方法作了介绍和比较,并详细论述了一些常用的方法,如二维魔角跳旋转(M a gic Angle Hopping, MAH)、二维魔角慢旋转(Magic Angle Turning, MAT)和二维变相旋转边带分离(2D phase-adjusted spinning sidebands, 2D-PASS)技术等. 最后,还介绍了单晶化学位移张量的常规测量方法.

关键词: 化学位移各向异性(CSA), 魔角跳旋转(MAH), 魔角慢旋转(MAT), 二维 变相旋转边带分离(2D-PASS), 张量主值

Abstract:

In rigid lattice, chemical shift is a tensor depending on the spatial orientation of the external magnetic field. The tensor has six independent components. The  orientation of chemical shielding tensor can be expressed with direction cosine s of its principal axis system. It is of great interest that if the chemical shi ft tensor of each nonmagnetically equivalent nucleus is known, the information o n the distribution of the electron cloud in the molecule can be deduced from the se tensors. In this paper, the theory and methods of measurement of chemical shi ft tensor are reviewed. A number of common methods are discussed in detail, such  as 2D magic angle hopping (MAH), 2D magic angle turning(MAT), and 2D phase-adjusted spinning sidebands(2D-PASS) technique and so on. The common metho ds for measuring single crystal chemical shielding tensor are also discussed.

Key words: chemical shift anisotropy (CSA) tensor, magic angle hopping (MAH), ma gic angle turning (MAT), 2D-PASS

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