High-resolution NMR spectroscopy of quadrupolar nuclei in solids: Satellite-transition MAS with self-compensation for magic-angle misset

Several methods are available for obtaining high-resolution NMR spectra of half-integer spin quadrupolar nuclei, such as 11B, 23Na (I = 3/2) and 17O, 27Al (I = 5/2), in powdered solids. Satellite-transition magic-angle spinning (STMAS) uses only conventional magic-angle spinning (MAS) hardware and, it has been claimed, improves significantly upon the signal-to-noise ratio obtained with the widely adopted multiple-quantum MAS (MQMAS) experiment. The STMAS technique, however, requiresthat the sample rotation axis be set to the magic angle (cos-1(1/√3) = 54.736°) with respect to the magnetic field B0 with an accuracy of better than ±0.004°, and this stringent requirement has severely limited the use of the method. Here, we propose a novel version of STMAS that self-compensates for magic-angle missets of up to ±1.0° and yet retains a sensitivity comparable with MQMAS. This SCAM-STMAS experiment is demonstrated on RbNO3 using 87Rb (I = 3/2) NMR and on kyanite (Al2SiO5) using 27Al (I = 5/2) NMR. Copyright © 2002 American Chemical Society.