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Theoretical Expression and Computer Simulation of Diffusion Behaviors in Multiple-Quantum Coherence NMR
Lin Qiaoling,Cai Shuhui*,Chen Zhong,Cai Congbo
Author NameAffiliationE-mail
Lin Qiaoling Department of PhysicsState Key Laboratory for Physical Chemistry of Solid SurfaceXiamen UniversityXiamen 361005  
Cai Shuhui* Department of PhysicsState Key Laboratory for Physical Chemistry of Solid SurfaceXiamen UniversityXiamen 361005 shcai@jingxian.xmu.edu.cn 
Chen Zhong Department of PhysicsState Key Laboratory for Physical Chemistry of Solid SurfaceXiamen UniversityXiamen 361005; State Key Laboratory of Magnetic Resonance and Atomic Molecular PhysicsWuhan Institute of Physics and MathematicsThe Chinese Academy of S  
Cai Congbo Department of PhysicsState Key Laboratory for Physical Chemistry of Solid SurfaceXiamen UniversityXiamen 361005  
Abstract:
Self-diffusion is one of the most fundamental motions of particles in liquid. Nuclear magnetic resonance (NMR)provides a convenient and noninvasive means for accurately measuring the self-diffusion coefficient of molecules in solution. The theoretical expressions of apparent diffusion rates of MQCs are given and computer simulation based on the method to measure the self-diffusion coefficient by NMR was discussed and the random walk model of particles is used to simulate the apparent diffusion behaviors of intra-molecular and inter-molecular multiple-quantum coherences(MQCs). The results of computer simulation agree well with theoretical predictions.
Key words:  NMR,Diffusion,Multiple-quantum coherences
FundProject:
核磁共振中多量子相干扩散行为的理论表述和计算机模拟
林巧玲,蔡淑惠*,陈忠,蔡聪波
摘要:
改进了Warren 所提出的CRAZED 脉冲序列以研究分子间多量子相干的扩散过程,讨论了利用核磁共振测量分子内和分子间多量子相干表观自扩散系数的理论表述,采用粒子的随机行走模型模拟其扩散行为. 在短脉冲近似和长脉冲梯度场两种实验条件下,分别获得了因扩散引起的不同相干阶数的相对信号衰减强度随梯度场脉冲间隔时间的变化曲线,由此得到分子内多量子相干和分子间多量子相干的表观扩散率与溶液分子扩散系数的关系. 还将计算机模拟结果与理论预测进行分析和比较,发现二者能很好地吻合. 研究结果表明,分子间多量子相干的表观扩散率与常规的分子内多量子相干的表观扩散率明显不同,因此,分子间多量子相干的表观扩散率可能提供一种新的核磁共振成像的对比度机理.
关键词:  NMR  扩散  分子间多量子相干  分子内多量子相干
DOI:10.1088/1674-0068/17/2/155-159
分类号: