Abstract
13C and 1H relaxation times of a coupled 13C–1H spin system dissolved in a nematic phase have been measured at 400 MHz (for 1H) by the selective and nonselective inversion recovery method. The relaxation times of doublet lines of each spin are different from each other. Especially, when a 1H line is inverted selectively, the relaxation time of the 13C line connected progressively to the inverted one is fairly different depending on which line of the 1H is inverted. Master equations for longitudinal relaxation are derived under the assumption that in addition to two relaxation mechanisms of the intramolecular dipole-dipole and external random field interactions, interference effects between the two might be nonnegligible in the oriented phase. The differences in the relaxation times have been explained by this interference effect.
