Nuclear Spin Relaxation in Gases and Liquids. V. Liquid Hydrogen

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Abstract
The theory of nuclear spin relaxation in gases and liquids developed by Bloom and Oppenheim is applied to the liquid‐hydrogen system. An explicit expression for T1 in terms of correlation functions of the anisotropic intermolecular potential is obtained. Two terms contribute to T1. The first term is independent of the ortho concentration and arises from the anisotropic potential that exists between an ortho molecule and a para molecule or the spherically symmetric part of another ortho molecule. It is suggested that three‐particle correlations must be explicitly considered if one is to understand the magnitude and the temperature and density dependence of this term. The second contribution is linear in the ortho concentration and arises from the anisotropic potential between the asymmetric part of two ortho molecules (quadrupole—quadrupole interaction). Theoretical calculation of this term agrees remarkably well with experiment. It is found that a dynamical model of the molecular motions (CAA) is more satisfactory than a diffusion model (DCAA) in the calculation of the quadrupole—quadrupole interaction effects.