Nuclear magnetic relaxation and random reorientations in molecular crystals

A calculation is made of the half‐width of the nuclear magnetic resonance line Δω 1/2 and the spin‐lattice relaxation time T 1 in molecular crystals. It is suggested that the relaxation is due to the modulation of the intermolecular dipole–dipole interaction of random reorientations of molecules. The random reorientations of molecules in a crystal lattice are treated on the basis of the random rotational travelling model, earlier suggested by the author. Δω 1/2 and T 1 are found to be determined by the number of equilibrium reorientations of the molecule. For different elementary rotational angles (π/2, π/4, π/6) calculation formulae are given. The nature of random reorientations is discussed.