MULTIPLE DIELECTRIC RELAXATIONS IN LIQUID-CRYSTALS, THEIR ANALYSIS AND INTERPRETATION

Dielectric measurements on laterally substituted molecules were carrie d out in the frequency range 10 Hz to 10 MHz. In these systems, the ma in part of the molecules exhibits only a very small dipole moment in t he direction of; the para-axis, whereas the lateral substituent is str ongly polar. Depending on the position of the dipole (o: in, p), a mor e or less strong dipolar correlation in the parallel direction was det ected. The absorption data at higher frequencies were fitted to two Co le-Cole mechanisms. The low frequency relaxation was interpreted as an gular vibration of the dipole moment of the lateral group, and the hig h frequency one as the reorientation about the para-axis of the main p art of the molecule and of the lateral group. The appearance of two hi gh frequency mechanisms is unexpected and demonstrates that in complic ated molecules the dynamics also become differentiated.