Multiple - quantum magic - angle spinning NMR: a new technique for probing quadrupolar nuclei in solids

We have recently described a new technique capable of recording high resolution NMR spectra of half - integer quadrupolar nuclei in solid samples, based on the combined use of magic - angle - spinning (MAS) and multiple - quantum (MQ) spectroscopy¹. This review summarizes the basic theoretical aspects underlying this high resolution MQMAS NMR experiment, emphasizing as well practical aspects involved in the optimization of its signal - to - noise. We also describe the features of MQMAS spectral lineshapes, and exemplify these with a number of applications on various quadrupolar nuclei. Also discussed is the occurrence of unusual spinning sideband patterns along the multiple - quantum domain; additional references to ongoing progress in the area that has appeared in the recent literature are also presented.