Theory of nuclear spin relaxation by translational self-diffusion in liquid crystals: Nematic phase

The theory of intermolecular nuclear spin relaxation by translational self-diffusion in liquid crystals is developed. Torrey's treatment of simple liquids is extended and modified for the liquid-crystalline phases by taking into account the anisotropy of the molecular motion, the elongated molecular shape, and the spin distribution on a molecule. Results, obtained for the frequency and angular dependence of $T_1$ in the nematic phase, are presented graphically for a variety of parameters and are compared with Torrey's results for classical liquids. A brief comparison with the available experimental data is presented.