Scalar coupling and frequency shift in liquid crystal solvents spinning at the magic angle

When a nuclear spin system dissolved in a liquid crystal is spun at the magic angle, it is shown that unusual N.M.R. spectral features are observed when the spinning frequency approaches the chemical shift difference between a pair of coupled nuclei. A detailed experimental analysis shows a strong enhancement of the sideband intensities as well as a resonance frequency shift analogous to a level anticrossing situation. The total frequency shift appears to be equal to the scalar spin-spin coupling between the nuclei concerned.