MULTIPLE-QUANTUM MAS NUTATION NMR-SPECTROSCOPY OF QUADRUPOLAR NUCLEI

Theory, experiments, and simulations of two-dimensional nutation NMR spectroscopy of half-integer quadrupolar nuclei combined with magic-angle spinning (MAS) are presented. MAS enhances the overall sensitivity and improves resolution in the ω2 2π dimension of the 2D nutation spectra. Compared to static nutation spectroscopy it is demonstrated that MAS nutation NMR puts less stringent requirements on the magnitude of the radiofrequency field strength, which is beneficial for nuclei with large quadrupole couplings. The finite nutation pulse excites all 2I(I + 1 2) multiple-quantum transitions for a spin-I nucleus. Multiple-quantum versions of the 2D nutation experiment are explored. Simulated 2D MAS nutation spectra are compared with experimental 23Na and 27Al spectra of NaNO3 and Ca3A12O6·6H2O (concrete), respectively, and with simulations of corresponding 2D nutation experiments for the static case. © 1992.