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 resolu tion NMR spectra of half - integer quadrupolar nuclei in solid samples, bas ed on the combined use of magic - angle spinning (MAS) and multiple - quant um (MQ) spectroscopy(1). This review summarizes the basic theoretical aspec ts underlying this high resolution MQMAS NMR experiment, emphasizing as wel l 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 di scussed is the occurrence of unusual spinning sideband patterns along the m ultiple - quantum domain; additional references to ongoing progress in the area that has appeared in the recent literature are also presented.