Correlation Functions in Nuclear Relaxation. I. Analysis of Random Motions from Field Dependence of Relaxation Times

Abstract

The contributions to T₁ in a fluid arising from spin—rotational interaction and chemical‐shielding anisotropy are discussed in terms of their simultaneous use to analyze the detailed nature of random rotations without the need of a microscopic theory. This possibility often exists because of the involvement of different correlation functions of the lattice variables and the experimental distinguishability of the latter mechanism through its magnetic‐field dependence. The method is illustrated by comparing the results to be expected for three different random processes: (1) rotational diffusion, (2) random walk among the m_j states of a rotational manifold of fixed J with no selection rules, (3) the same with a rigorous Δm_j=±1 selection rule. Possible favorable experimental cases are discussed.