Pressure and Temperature Studies of NMR Translational Relaxation in Hydrogen Bonded Liquids

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Abstract
Spin-lattice and spin-spin relaxation time have been measured using the spin echo method in three hydrogen bonded liquids: glycerol, 1,3-butanediol, and 2-methyl-2,4-pentanediol as a function of temperature through the region of the T1 minimum and at seven pressures in the range 0–3000 kg/cm2. The results of this study lead to the conclusion that the translational model for NMR relaxational presented by Torrey is satisfactory for representing the diffusive motion of molecules in these viscoelastic liquids. Agreement between the experimentally measured values of the self-diffusion constant and those theoretically predicted by the translational theory provides verification of this assumption. Recent measurements of quadrupolar-relaxation times as a function of temperature on deuterated glycerol as well as low frequency proton spin-lattice relaxation measurements also provide supporting evidence. The nuclear correlation time τC, the mean time between diffusive jumps τj, and the distance of closest approach d are produced from a fit of the T1 and T2 data to the translational relaxation theory. The values τC and τj are compared to the corresponding times obtained from dielectric, ultrasonic and light scattering experiments.