35Cl and 19F NMR Spin–Lattice Relaxation Time Measurements and Rotational Diffusion in Liquid ClO3F

Abstract

The NMR spin–lattice relaxation times of 35Cl and been 19F have measured by pulse techniques over the entire liquid range of ClO3F (130–368°K). The chlorine relaxation which is due solely to the nuclear quadrupole interaction can be used together with the known quadrupole coupling constant to determine the correlation time for molecular orientation, τθ,2. The fluorine relaxation is dominated by the spin–rotation interaction with only a small intermolecular dipole contribution at the lowest temperatures. In order to obtain the angular momentum correlation time, τJ, an independent estimate of the spin–rotation tensor was made by combining gas-phase measurements of T1(19F) with previous data on the chemical shift and gas-phase dielectric relaxation. The results for this quasispherical molecule are in accord with rotational diffusion theory and Hubbard's relation, τθ,2τJ = I / 6kT, at the lowest temperatures and agree over the entire range with the extended treatment of McClung.