波谱学杂志 ›› 1999, Vol. 16 ›› Issue (6): 485-493.

• 研究论文 • 上一篇    下一篇

两位置交换问题魔角旋转核磁共振时域信号的准确解

沈伊民1,2, Hironori KAJI2, Fumitaka HORII2   

  1. 1. 复且大学分析测试中心, 上海 200433;
    2. 京都大学化学研究所, 京都 611-0011 日本
  • 收稿日期:1999-08-17 修回日期:1999-09-17 出版日期:1999-12-05 发布日期:2018-01-13
  • 作者简介:沈伊民,1961年出生,理学博士,副教授
  • 基金资助:
    This work was financially supported by Grant 2974006 from the NSFC, by the foundation for returned scholar from the education ministry of China and by the Laboratory of MRAMP

AN EXACT SOLUTION OF A MAS FID IN TWO-SITE EXCHANGE PROBLEM

SHEN Yimin1,2, Hironori KAJI2, Fumitaka HORII2   

  1. 1. Analytical Center, Fudsn University, Shanghai 200433;
    2. Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
  • Received:1999-08-17 Revised:1999-09-17 Online:1999-12-05 Published:2018-01-13
  • Supported by:
    This work was financially supported by Grant 2974006 from the NSFC, by the foundation for returned scholar from the education ministry of China and by the Laboratory of MRAMP

摘要: 已知两位置交换分子运动速率对于静态13CNMR谱的影响是由一简单代数关系决定,它已成为分析固体中分子运动的常规方法.慢速的魔角旋转可以保留边带,所产生的边带型原则上也可用来分析分子运动,只是缺乏象静态谱那样的简单的关系,以至于在实际应用上是不可行的.本文给出作者所发现的存在分子运动时魔角旋转核磁共振自由诱导衰减信号的解析表达式的理论推导,提供分析固体分子运动的理论谱计算公式.我们选择二甲矾(dimethylsulfone)作为模型化合物,记录其不同温度下13CNMR谱,又计算了两个甲基做两位置交换运动的理论谱.理论谱与实验谱定性一致.定量上,边带强度存在一些差别,但边带宽度符合很好.通过理论谱与实验谱的比较,得到交换速率与温度的对应关系.虽然本文限于化学位移各向异性相互作用两位置交换问题,但容易推广到偶极作用多位置交换问题.

关键词: 核磁共振, 魔角旋转, 两位置交换, 准确解

Abstract: An exact solution of a magic-angle-spinning free-induction-decay under two-siteexchange has been derived. The expression has been confirmed by comparing the calculated spinningsideband patterns for powdered crystalline dimethyl sulfone at different exchange rates with experimentally measured CP/MAS 13C NMR spectra at various temperatures. The information of themode and the site exchange rate constants of molecular motion can be provided by spectral line fittingbetween calculated and experimental spectra. The numerical calculations with this algorithm showthat the exchange effect results in a slight narrowing of the centerband and a slight broadening ofsidebands compared to the equal, linewidtbs without exchange.

Key words: NMR, Magic angle spinning, Two-site exchange, Exact solution