核自旋单重态的制备及其转化效率和寿命的影响因素分析

doi:10.11938/cjmr20192725

摘要/Abstract

摘要： 长寿命核自旋单重态（LLS）因具有寿命较长这一特性而具有广泛的应用前景.本文在一个三肽样品（alanylglycylgcine，AGG）的水溶液中，对结构中离手性碳较远的二自旋体系进行核自旋单重态的制备，并探究了样品浓度、温度、射频发射中心位置、自旋体系之间的J耦合常数，以及磁场不均匀性五个因素对LLS的转化效率及其寿命的影响.实验结果表明，核自旋单重态的转化效率和寿命均不受样品浓度以及磁场不均匀性的影响.寿命会随实验温度的升高不断增加，转化效率随温度的下降而减小.射频中心位置在小范围内变化时，核自旋单重态制备所受影响不明显；但当变化较大时，其转化效率与寿命明显减小.同时，核自旋单重态对J耦合的变化则比较敏感，当J值选择不精准时，转化效率及寿命都出现明显降低.

关键词: 核自旋单重态, 强耦合体系, 转化效率, 核磁共振(NMR)

Abstract: The long-life nuclear spin singlet states (LLSs) have broad application prospects due to the unique nature of their long lifetime. Herein, in a solution of alanylglycylgcine (AGG), the nuclear spin singlet state of a two-spin system far from the chiral carbon in the structure is prepared. Then, the effects of sample concentration, temperature, radiofrequency (RF) center, J-coupling value and magnetic field inhomogeneity on conversion efficiency and lifetime of the LLSs were investigated. The experimental results showed that the conversion efficiency and lifetime of the singlet state were not affected by the sample concentration and magnetic field inhomogeneity, but increased with increasing experimental temperature. The influence of the position of RF center on the singlet state was not obvious when it changed within a small range, but the conversion efficiency and lifetime reduced significantly when the changes were large. Moreover, the singlet state was found to be sensitive to the changes of J-coupling value. The conversion efficiency and lifetime reduced significantly with choose of non-accurate J-coupling constant.

Key words: nuclear spin singlet state, strong-coupling system, conversion efficiency, nuclear magnetic resonance (NMR)

中图分类号:

O482.53

刘慧霞, 辛家祥, 魏达秀, 姚叶锋. 核自旋单重态的制备及其转化效率和寿命的影响因素分析[J]. 波谱学杂志, 2020, 37(2): 182-192.

LIU Hui-xia, XIN Jia-xiang, WEI Da-xiu, YAO Ye-feng. Preparation of Nuclear Spin Singlet States and Analysis of Influencing Factors on Their Conversion Efficiency and Lifetime[J]. Chinese Journal of Magnetic Resonance, 2020, 37(2): 182-192.

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