Fluorine magnetic resonance of solid chloropentafluorobenzene

Abstract

The nuclear magnetic resonance absorption spectrum of solid chloropentafluorobenzene has been studied at temperatures between 77 °K and the melting point. The experimental values of the second moment have been divided into two parts, one due to broadening by nuclear dipole-dipole interactions and the other due to broadening by the anisotropy of the fluorine chemical shift. The absorption line begins to narrow at 190 °K, close to the temperature of a specific heat anomaly. Consideration of the effects of molecular motion on both parts of the second moment show that the narrowing is due to rotation about an axis perpendicular to the plane of the molecule.