Nuclear magnetic spin relaxation of a spin-pair undergoing reorientations by jumping among unequivalent sites

Abstract

The nuclear magnetic dipole-dipole relaxation has been calculated for a two-spin system which undergoes an isotropic motion associated with an internal motion. The model for the internal motion is jumps among inequivalent three sites, two of which are equivalent. Calculations have been carried out for two cases, the first being a spin-pair having a time-independent internuclear distance, and the second being a spin-pair whose internuclear distance varies as a result of internal motion. Some numerical calculations of the spin-lattice relaxation time and the nuclear Overhauser enhancement of ¹³C-{¹H} for the first case and the spin-lattice relaxation time of ¹H-¹H for the second case are presented.