Nuclear Spin Relaxation by Translational Diffusion in Liquid Ethane

Abstract

Torrey's theory for nuclear spin relaxation by translational diffusion has been extended to take into account the effect of the radial distribution function. By suitable expansions, the frequency dependence of the intermolecular relaxation rate has been made explicit and shown to be more significant than previously suspected. Measurements of self-diffusion and of the intermolecular relaxation of protons in liquid ethane have been made over a wide range of temperatures and at three frequencies in order to test the theory. Good agreement is obtained with the assumption of an rms flight distance which varies monotonically from about 0.8 to 1.3 times the molecular diameter over the liquid range.