Diffusion and Nuclear Spin Relaxation in Water

The diffusion coefficient and the spin lattice relaxation time of protons in ordinary water have been measured in the temperature range 0-100\ifmmode^\circ\else\textdegree\fi{}C using nuclear magnetic resonance free precession techniques. Unlike previous diffusion measurements, the present values describe the diffusion of protons rather than foreign isotopes introduced as tracers. To within the experimental error the Stokes-Einstein relation adequately describes the relative temperature dependence of viscosity and diffusion, but above the vicinity of 40\ifmmode^\circ\else\textdegree\fi{}C the spin lattice relaxation does not follow the viscosity in the predicted manner.