Nuclear spin relaxation in hydrogen gas

Abstract

The proton spin–lattice relaxation time T1 in normal H2 gas has been measured as a function of temperature between 293 °K and 738 °K and pressure between 7 and 135 atm. These data and previous measurements at lower temperatures are analyzed in terms of a generalized theory which takes into account the influence of collisions which change the rotational quantum number J as well as those which only change MJ. It is concluded that collisions which change J play an important role even at temperatures as low as 200 °K. The relative importance of different types of inelastic collisions which give rise to changes in J is discussed. Some preliminary results of the radial dependence of the anisotropic H2–H2 interaction are given, but more accurate measurements of T1 as a function of ortho-H2 below room temperature are required to make a definitive interpretation.