Estimation of natural linewidths in exchange-broadened nuclear magnetic resonance spectra

Abstract

A general method for the estimation of natural linewidths in exchange-broadened n.m.r. spectra is described. The procedure is especially useful in systems for which the exchange rate can be reduced only by lowering of the temperature and where this temperature reduction is accompanied by viscosity-broadening of the spectra. The method is based on the empirically known proportionality (in the absence of exchange) between the spin–spin relaxation rate and the spin–lattice relaxation rate. Its application is illustrated with reference to solutions of various solute bases in the viscous superacid medium fluorosulphuric-acid–antimony-pentafluoride.