Satellite transitions in MAS NMR spectra of quadrupolar nuclei

Abstract

Manifolds of spinning sidebands (ssb's) are observed for the satellite transitions of several half-integer quadrupolar nuclei (spin I 1 2 ) using one-pulse magic-angle spinning (MAS) NMR experiments of crystalline powders. Numerical simulations of the variety of envelope patterns for the ssb's in such spectra show that the quadrupolar coupling parameters can be determined with high accuracy. The theory of the method is described and evaluated using average Hamiltonian theory to first and second order in the secular approximation. The influence of finite RF pulse excitation and quality factor of the MAS probes on the ssb intensities in the spectra is analyzed. Determination of quadrupole coupling constants and asymmetry parameters for the electric field gradient tensors from 17O, 23Na, and 27Al MAS NMR spectra of various solids illustrates the theory and high performance of the method.