Linewidth analysis of the proton resonance spectrum of benzene in a nematic solution

A nonaromatic nematic solvent consisting of an equimolar mixture of trans-4-n-butyl and trans-4-n-hexyl-cyclohexane-l-carboxylic acid was used to study the hydrogen NMR spectrum of partially oriented benzene. Variations in linewidths between 0.7 and 2.6 Hz could be observed but there was no strong correlation between splitting frequency and linewidth. The spectrum was analyzed using the Redfield theory considering intramolecular and intermolecular dipolar relaxation separately. Best agreement with the experiment is obtained by combining intermolecular relaxation effects with the zero frequency term of the intramolecular relaxation which gives contributions to the linewidths that are proportional to the square of the splitting frequency. The results indicate that the intermolecular interactions dominate and that intramolecular interactions become of importance only due to relatively slow director fluctuations. © 1982.