Nuclear Spin Relaxation in Gaseous H2 at Low Densities

The longitudinal and transverse nuclear relaxation times, T1 and T2, have been measured in normal H2 gas at 77.5 °K in the pressure range 0.05–2 atm. In this region T1 goes through a minimum, and T2 deviates significantly from a linear dependence on the density. Comparison of the experimental data with existing theory establishes the following results for the J = 1 state of ortho-hydrogen: (i) Autocorrelation functions of the molecular angular momentum operators are exponential or nearly so. (ii) The ratio of the correlation times τ1 and τ2 that are associated with operators of the form Jz and 3JZ2 − J(J + 1), respectively, lies within the limits [Formula: see text] (iii) The splitting of the molecular Zeeman levels cannot be neglected as in the original Schwinger theory.