中国物理B ›› 2005, Vol. 14 ›› Issue (3): 516-523.doi: 10.1088/1009-1963/14/3/015

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Multiplet patterns due to co-existing intermolecular dipolar and intramolecular scalar couplings in liquid nuclear magnetic resonance

朱小钦1, 蔡聪波1, 陈忠2, 钟健晖3   

  1. (1)Department of Physics, State Key Laboratory for Physical Chemistry of Solid Surface, Xiamen University, Xiamen 361005, China; (2)Department of Physics, State Key Laboratory for Physical Chemistry of Solid Surface, Xiamen University, Xiamen 361005, China; Departments of Radiology and Physics and Astronomy, University of Rochester, Rochester, NY 14642, USA; (3)Departments of Radiology and Physics and Astronomy, University of Rochester, Rochester, NY 14642, USA
  • 收稿日期:2004-08-24 修回日期:2004-10-20 出版日期:2005-03-02 发布日期:2005-03-02
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10234070 and 10375049) and National Institutes of Health (Grant No NS41048).

Multiplet patterns due to co-existing intermolecular dipolar and intramolecular scalar couplings in liquid nuclear magnetic resonance

Zhu Xiao-Qin (朱小钦)a, Cai Cong-Bo (蔡聪波)a, Chen Zhong (陈忠)ab, Zhong Jian-Hui (钟健晖)b   

  1. a Department of Physics, State Key Laboratory for Physical Chemistry of Solid Surface, Xiamen University, Xiamen 361005, China; b Departments of Radiology and Physics and Astronomy, University of Rochester, Rochester, NY 14642, USA
  • Received:2004-08-24 Revised:2004-10-20 Online:2005-03-02 Published:2005-03-02
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10234070 and 10375049) and National Institutes of Health (Grant No NS41048).

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摘要： When both intermolecular dipolar couplings (D couplings) and intramolecular scalar couplings (J couplings) exist in a highly polarized multiple-spin liquid, some forbidden nuclear magnetic resonance signals originating from intermolecular multiple-quantum coherences may become observable. Moreover, their multiplet patterns are quite different from what are observed in a multiple-spin system with J couplings only. In this paper, these forbidden resonance peaks and unique multiplet patterns are studied theoretically and experimentally. For comparison and verification, an I2S3+X spin system is chosen as an example to present five types of signal patterns from the interactions of D and J couplings with either selective or non-selective radio-frequency pulse sequences for double-quantum coherences. The multiplet pattern rules for a more general IpSq+Xk (p, q, k=1, 2, 3,…) spin system are derived as well. It is demonstrated that some unusual multiplet amplitude patterns such as (1:0:—1) may "magnify" J splittings, allowing more accurate measurement of J coupling in the case of small J coupling constants and/or in inhomogeneous fields. It is shown that the theoretical predictions, computer simulations, and experimental observations are all in agreement with one another very well.

关键词: nuclear magnetic resonance, intermolecular multiple-quantum coherences, dipolar and scalar couplings, multiplet patterns

Abstract: When both intermolecular dipolar couplings (D couplings) and intramolecular scalar couplings (J couplings) exist in a highly polarized multiple-spin liquid, some forbidden nuclear magnetic resonance signals originating from intermolecular multiple-quantum coherences may become observable. Moreover, their multiplet patterns are quite different from what are observed in a multiple-spin system with J couplings only. In this paper, these forbidden resonance peaks and unique multiplet patterns are studied theoretically and experimentally. For comparison and verification, an I2S3+X spin system is chosen as an example to present five types of signal patterns from the interactions of D and J couplings with either selective or non-selective radio-frequency pulse sequences for double-quantum coherences. The multiplet pattern rules for a more general IpSq+Xk (p, q, k=1, 2, 3,…) spin system are derived as well. It is demonstrated that some unusual multiplet amplitude patterns such as (1:0:—1) may "magnify" J splittings, allowing more accurate measurement of J coupling in the case of small J coupling constants and/or in inhomogeneous fields. It is shown that the theoretical predictions, computer simulations, and experimental observations are all in agreement with one another very well.

Key words: nuclear magnetic resonance, intermolecular multiple-quantum coherences, dipolar and scalar couplings, multiplet patterns

中图分类号:  (Nuclear resonance and relaxation)

  • 33.25.+k
76.60.-k (Nuclear magnetic resonance and relaxation)