C-13 NMR OF CARBON-MONOXIDE .2. MOLECULAR-DIFFUSION AND SPIN-ROTATION INTERACTION IN LIQUID CO

Carbon-13 NMR was used to measure the molecular diffusion coefficient D and the spin-rotation correlation time τsr in liquid CO from its freezing point to about 110 K at several pressures up to 1.73 kbar. The behavior of D and τsr is similar for liquid CO and N2. Diffusion in CO at equilibrium vapor pressure takes place with an activation enthalpy of 2.9 kJ/mole and its pressure dependence leads to an activation volume which is a factor of 5 smaller than in the solid phase just below freezing. τsr is nearly equal for CO and N2 at T ≤ 80 K and its variation with pressure for CO is smaller than that of D by almost a factor of 2. We also present a method for determining the magnetic field gradient used in the measurement of D which is free from many of the usual problems. © 1979 American Institute of Physics.