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本文第一章系统地阐述了多量子NMR的基本理论,以及研究多量子相干弛豫的重要意义;评述了多量子相干弛豫研究的最新进展及多量子相干弛豫时间的测量方法。 第二章针对AX、AX_2和AX_3体系提出了两种直接测量多量子相干弛豫时间的脉冲序列。根据超算符和密度矩阵理论对所建议的脉冲序列作了分析;在实验上通过改变实验参数,可以实现只有某阶多量子相干存在的多量子滤波,因此可以用类似于常规单量子弛豫时
The first chapter of this paper systematically expounds the basic theory of multi-quantum NMR and the importance of studying the multi-quantum coherent relaxation. The latest development of multi-quantum coherent relaxation research and the measurement of multi-quantum coherent relaxation time are reviewed. In the second chapter, two kinds of pulse sequences for direct measurement of multiple quantum coherent relaxation time are proposed for the AX, AX_2 and AX_3 systems. The proposed pulse sequence is analyzed according to the hyper-operator and density matrix theory. Experimentally, by changing the experimental parameters, we can realize the multi-quantum filter with some quantum multiple coherence, so we can use the similar single quantum relaxation Time