Proton Spin Relaxation Study of the Dipolar Spin System in Nematic Liquid Crystals

The proton spin dipolar relaxation time was measured in the mesophases of p-azoxyanisole, p-n-hexyloxyazoxybenzcne, p-n-heptyloxyazoxybenzene and p-methoxybenzylidene-p-n-butylaniline as a function of temperature and frequency. It was found that the dipolar spin systems in the nematic crystalline phase are predominantly relaxed by the orientational order fluctuations. This is manifested by the magnetic field effects on the order fluctuation modes.