Nuclear Magnetic Relaxation and Overhauser Effects in Liquid CHF3

Abstract

The longitudinal nuclear magnetic relaxation, transient and steady-state Overhauser effects, and diffusion coefficient of the protons and fluorine nuclei in liquid CHF3 have been measured by pulsed magnetic resonance techniques at temperatures between 113° and 173°K. Interpretation of the data gives values of the contributions to the relaxation due to intra- and intermolecular dipole—dipole, and spin—rotational interactions. The effects of intermolecular dipole—dipole interactions are found to be larger than the effects of intramolecular dipole—dipole interactions. The intermolecular dipole—dipole contributions are larger, and the intramolecular contributions are smaller, than is predicted by the familiar theory that relates these contributions to the diffusion coefficient. The effects of the spin—rotational interactions of the fluorine nuclei are important, but the effects of the spin—rotational interactions of the protons are negligible. This investigation demonstrates that the use of Overhauser-effect data in addition to relaxation-rate data facilitates the determination of the effects of dipole—dipole and spin—rotational interactions.