Intermolecular Multiple-Quantum Coherences Under Three-Pulse Sequences

Over the past decade, the intermolecular multiple-quantum coherence (iMQC) phenomena in highly polarized nuclear spin systems have attracted great attention in research community of nuclear magnetic resonance. They have found many important applications in magnetic resonance spectroscopy and magnetic resonance imaging. The simple CRAZED pulse sequence with two radio-frequency pulses is enough to detect iMQCs. Great progress has been made in our understanding of the physical basis and characteristics of iMQCs by using two-pulse sequence, and novel applications in biomedical research haven been proposed. Nevertheless, there still exist some problems to be resolved. Moreover, many NMR experiments, especially in protein NMR experiments, more complex sequences are in common use. Therefore, in this work, we focused our attention on the properties, physical mechanism, and applications of iMQCs under three-pulse sequence.Since the detection of the conventional MQCs requires at least three pulses, they were excluded in the previous research of iMQCs under two-pulse sequence. Furthermore, for convenience, only systems without scalar coupling were studied. However, most samples have scalar couplings, hence conventional MQCs would be observed when three or more pulses are applied. Therefore, in this work, multiplet patterns of iMQC signals due to the co-existing of scalar coupling and dipolar coupling by two-pulse sequence were studied firstly. Secondly, in order to study the characteristics of signals consisting of intra- and inter-molecular MQCs, selection and suppression of these two kinds of signals were preformed. Next, although the residual dipolar interactions have found many applications,...