Nuclear Spin Relaxation and the Collision Frequency in Dense Gases

The relation between nuclear spin-lattice relaxation (T1) measurements and the collision frequency in dense gases is discussed. It is shown that the density dependence of T1 in compressed H2 gas can be accounted for by assuming a hard-sphere potential model and evaluating the Enskog correction to the collision frequency in a dense fluid. This comparison represents the first direct test of the collision frequency in a dense fluid.