NUCLEAR MAGNETIC SPIN RELAXATION OF A SPIN-PAIR UNDERGOING REORIENTATIONS BY JUMPING AMONG UNEQUIVALENT SITES

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 in-equivalent 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 of13C{1H) for the first case and the spin-lattice relaxation time of1H—1H for the second case are presented. © Taylor & Francis Group, LLC.