Nuclear spin relaxation in systems of magnetic spheres

Abstract A new approach to the NMR relaxation theory for a system of magnetic spheres (sufficiently big spherical molecules) is presented. In this paper the NMR spin–lattice relaxation time T 1 and spin–spin relaxation time T 2 are calculated for nuclear spins I → j , taking into account intermolecular dipole–dipole interactions between the spins I → j , and spins S → k in the magnetic spheres. By an expansion of the dipole–dipole interaction in a series of spherical harmonics, it is possible to separate spatial variables of the interacting spins in a laboratory frame. A simultaneous effect of isotropic rotational and translation diffusion of the spins and relaxation rate of spins S → k is also taken into account.