Theory of Nuclear Magnetic Relaxation by Spin-Rotational Interactions in Liquids

摘要: The contribution of spin-rotational interactions to the nuclear magnetic relaxation identical spin-\textonehalf{} nuclei at equivalent positions in spherical liquid molecules is calculated by use semiclassical form density-operator theory relaxation, and result compared with contributions intra- intermolecular dipole-dipole interactions. angular velocity a molecule treated classically assuming that it obeys an equation analogous Langevin postulated treatments translational Brownian motion. change orientation assumed be due isotropic rotational By this model correlation functions components are calculated, found have exponentially decaying time dependence constant (correlation time) ${\ensuremath{\tau}}_{1}$ quite different its temperature than ${\ensuremath{\tau}}_{2}$ In typical situations much smaller ${\ensuremath{\tau}}_{2}$. Use made fact evaluate occur tensor ${\ensuremath{\tau}}_{1}\ensuremath{\ll}{\ensuremath{\tau}}_{2}$ explains experimentally observed "quenching" effect liquids, ${\ensuremath{\tau}}_{1}T$ increases as liquids.