Two-Dimensional Satellite-Transition MAS NMR of Quadrupolar Nuclei: Shifted Echoes, High-Spin Nuclei and Resolution

Abstract Modifications to the satellite-transition magic angle spinning (STMAS) experiment for obtaining high-resolution NMR spectra of quadrupolar nuclei are discussed. A phase-modulated 'shifted-echo' STMAS experiment that yields pure absorptive lineshapes is presented and shown to be compatible with the 'split-t1' technique used in multiple-quantum (MQ) MAS NMR to reduce the duration of t2 acquisition and avoid shearing the final two-dimensional spectrum. The application of STMAS to nuclei with spin greater than I = 3/2 is also considered, the dispersion of isotropic shifts achieved by STMAS and MQMAS are compared, and the effects of anisotropic 'cross-term' broadening mechanisms on linewidths in 'isotropic' STMAS spectra are discussed.

Two-dimensional (a) 23Na and (b) 17O STMAS NMR spectra of (a) Na2SO4/Na2C2O4 and (b) Mg2SiO4.