Theory of nuclear magnetic relaxation by dipolar interaction

A theoretical study is made of nuclear magnetic relaxation by dipole-dipole interactions, when the molecules containing the dipoles are subject to random thermal motion. Relaxation rates are expressed in terms of spectral densities for both intermolecular and intramolecular interactions. Analytical expressions for relaxation rates are derived in an inertial theory for various molecular models. Rotational diffusion results obtained for a spherical molecule may be applied to a linear or a symmetric molecule. (orig.)