High Pressure NMR Study of the Molecular Dynamics of Liquid Methylfluoride and Deutero‐Methylfluoride

The 2 D‐, 1 H‐ and 19 F‐spin‐lattice relaxation rates R 1 , have been investigated in fluid methylfluoride in the temperature range 150 K ≤ T ≤ 450 K and at pressures up to p = 200 MPa. In addition, the self‐diffusion coefficient D has been obtained with NMR techniques in the same p. T ‐interval. — The latter are interpreted within the rough hard sphere model yielding a temperature independent RHS diameter d and a strongly temperature dependent rotation‐translation coupling parameter A. The total 2 D‐, 1 H‐ and 19 F‐relaxation rates in CD 3 F and CH 3 F are decomposed into their respective quadrupolar, dipolar and spin‐rotation contributions. Furthermore orientational and spin‐rotational correlation times are estimated. It is shown that they are in good agreement with the predictions of the extended M‐diffusion model (EDM). Inertial effects influence the molecular dynamics in the whole p, T ‐range investigated. The self‐diffusion coefficients and orientational correlation times are in excellent agreement with MD‐simulation data.