Abstract
Deuterium quadrupole echo spectroscopy has been used to probe the orientational behaviour and dynamics of CDCl3 molecules in ethylcellulose/chloroform chiral nematic phases. The 2H spectra of both left-handed and right-handed mesophases, formed by ethylcellulose with degrees of substitution of 2·3 and 3·0 respectively, were examined as functions of temperature and concentration. The observed quadrupolar splittings are relatively large and the magnitudes of the order parameters of the solvent molecules show little correlation with the handedness of the chiral phases. However, the 2H line shapes of these two types of chiral phase exhibit rather different temperature dependences. Spectral simulations show that the observed line shapes and their temperature variations are mainly determined by diffusion of CDCl3 molecules along the pitch axis. The effects of centrifugation on the 2H spectra are also described.