DIELECTRIC-RELAXATION PROCESSES IN THE NEMATOGEN 4-CYANOPHENYL 4-N-HEPTYLBENZOATE

Experimental studies of the dielectric relaxation in the nematic and i sotropic phases of 4-cyanophenyl 4-n-heptylbenzoate have been performe d in the frequency range from 1 kHz to 1 GHz. In the nematic phase, me asurements of the complex dielectric permittivity for two orientations of the director n, parallel and perpendicular to the measuring electr ic field E, have been carried out. It has been found that for E parall el to n, as well as in the isotropic phase, the dielectric spectra con sist of two elementary domains, described by the Cole-Cole equation, w hereas for E perpendicular to n three Cole-Cole-type domains can be di stinguished. The possible molecular reorientational movements correspo nding to these domains are discussed and comparison with the theoretic al predictions is made.