A comparison of correlation function and kinetic theory methods in the calculation of NMR relaxation times in dilute monatomic gases

Abstract

The values of T1 in monatomic spin ½ Systems calculated with the constant acceleration approximation (CAA) are compared with the values of T1 calculated with an exact kinetic theory. The hard sphere potential as well as realistic potential functions for the spherical interaction between atoms are employed in the comparisons. T1 is calculated for both the dipolar and spin–rotation spin dependent interactions. The results indicate that the constant acceleration approximation will be useful for Systems having a slowly varying repulsive spherical potential and a long-range radial dependence for the spin dependent interation. Also, if the symmetry properties of the anisotropic potential are such that large impact parameters make the major contribution, then the CAA will be a valid approximation.