Nuclear Magnetic Relaxation and Diffusion in Liquid CH4, CF4, and Mixtures of CH4 and CF4 with Argon

Publisher Website
Google Scholar
Abstract
The longitudinal nuclear magnetic relaxation times and diffusion coefficients of CH4, CF4, and mixtures of CH4 and CF4 with argon have been measured at temperatures between the freezing points and the boiling points of the liquids by use of spin‐echo techniques. Misch metal was used as a getter to remove oxygen from the samples. The relative numbers of spins per unit volume have also been measured. The measured values of the relaxation time T1 are compared with values calculated on the assumption that the relaxation is due to spin—rotational interactions and to intra and intermolecular dipole—dipole interactions. The calculated and measured values of (1/T1) differ by a factor of as much as 4 for pure liquid CH4 and as much as 12 for the argon—CH4 mixture. The calculated and measured values of (1/T1) for pure liquid CF4 and for the argon—CF4 mixture agree quite well if reasonable values of the spin—rotational interaction constants are assumed. The calculated contribution of the spin—rotational interactions to (1/T1) is negligible for liquid CH4, and is comparable to the contributions of the dipole—dipole interactions for liquid CF4.