Translational and Anisotropic Rotational Diffusion in Liquid Chloroform as Studied by NMR Relaxation

Abstract

AbstractThe proton spin‐lattice relaxation rate of liquid chloroform was measured in the neat liquid and in CHCl3/CDCl3mixtures over the temperature range – 18° to 47°C. Translational self‐diffusion constants are reported in the same temperature range.The intramolecular proton rate obtained from the isotopic dilution measurements is split into a spin‐rotational part and a contribution from the proton‐chlorine dipolar interaction. The spin‐rotational rate is then evaluated by use of a formula which takes into account the anisotropic rotational diffusion of a symmetric‐top molecule. This equation is derived in a theoretical section. The results show that the diffusion equation provides the correct description for the rotational motion.The intermolecular dipolar proton‐proton relaxation rate obtained from the dilution experiments is used to check current theories. None of these describes the experimental results adequately. Various reasons for this failure are discussed.