Carbon-13 NMR study of molecular reorientation in glycerol

The 13C spin-lattice relaxation time T1 has been measured as a function of temperature by the PRFT technique in a sample of carefully dried glycerol. Data were taken between 267 and 339°K and the results fitted to a theoretical description of relaxation involving unlike spins which are undergoing anisotropic reorientation. The best fit gave a ratio of rotational diffusion coefficients of 1:5:200 and an activation energy for molecular reorientation of 2.41±0.05 kcal/mole. The results indicate that it is not necessary to invoke a continuous distribution of correlation times in order to describe the relaxation behavior. A speculative model for rotational and translational motion, consistent with the results of previous studies, is presented.