Theoretical formalism and experimental verification of line shapes of NMR intermolecular multiple-quantum coherence spectra.
Theoretical formalism and experimental verification of line shapes of NMR intermolecular multiple-quantum coherence spectra.
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DOI：
10.1063/1.2001652
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发表时间：
2005-08
期刊：
影响因子：
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通讯作者：
B. Zheng;Zhong Chen;S. Cai;J. Zhong;C. Ye
中科院分区：
文献类型：
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作者：
B. Zheng;Zhong Chen;S. Cai;J. Zhong;C. Ye
虽然分子间多量子相干（iMQC）的理论和潜在应用已经进行了十多年的积极研究，但对iMQC NMR信号形成的讨论主要局限于时域。本文提出了一种在频域中描述iMQC信号的全线形理论。对谱线的峰高、线宽和相位等有关特征进行了详细的研究。基于理论的预测与实验和模拟结果吻合良好。由于在高极化液态NMR系统中，辐射阻尼效应总是与iMQCs相耦合，而强辐射阻尼信号具有许多与iMQCs相似的光谱特征，因此从不同的光谱角度对它们进行了详细的比较。通过对峰高、线宽和相位的详细比较，这项工作证明了iMQC和辐射阻尼现象是由两种完全不同的物理机制引起的，尽管两者都呈现出相似的信号特征，并共存于高度极化的液态NMR系统中。
Although the theories and potential applications of intermolecular multiple-quantum coherences (iMQCs) have been under active investigations for over a decade, discussion of iMQC NMR signal formation was mainly confined in the time domain. In this paper, a full line-shape theory was developed to describe iMQC signals in the frequency domain. Relevant features of the line shape, such as peak height, linewidth, and phase, were investigated in detail. Predictions based on the theory agree well with experimental and simulated results. Since radiation-damping effects always couple with iMQCs in highly polarized liquid-state NMR systems, and strongly radiation-damped signals have many spectral characteristics similar to those of iMQCs, a detailed comparison was also made between them from different spectral aspects. With detailed comparison of peak height, linewidth, and phase, this work demonstrates that the iMQC and radiation-damping phenomena result from two completely different physical mechanisms despite that both present similar signal features and coexist in highly polarized liquid-state NMR systems.