Orientation order and dynamics of CDCl3 in ethylcellulose/chloroform liquid crystal phases

Deuterium quadrupole echo spectroscopy has been used to probe the orientational behaviour and dynamics of CDCl 3 molecules in ethylcellulose/chloroform chiral nematic phases. The 2 H 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 2 H 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 CDCl 3 molecules along the pitch axis. The effects of centrifugation on the 2 H spectra are also described.