Theory of zero-field NMR spectra. Effects of motion

Zero-field NMR spectra of tunnelling methyl group, classically reorienting methyl group and of a pair of spins 1/2 jumping between two perpendicular orientations are calculated. A formula for the second moment of a rigid lattice is derived from a formal analogy between zero-field and high-field spectra. Fast reorientation about a perpendicular axis reduces the intramolecular second moment to 1/4 of its rigid value. The zerofield method seems to be a promising tool for the determination of tunnelling splitting or of jumping rates.