Dielectric spectroscopy study of the transition into the hexatic phase in chiral smectics

Collective molecular motion was studied by dielectric spectroscopy up to 10 MHz in the vicinity of both ferroelectric SmC* - hexatic SmI* and antiferr oelectric SmCA* - hexatic SmIA* phase transitions. A single relaxation proc ess has been found in all studied phases except for the SmCA* phase, where no relaxation process could be detected. These relaxations have been attrib uted to fluctuations of bond orientation order coupled to the tilt and pola rization. This coupling is also responsible for the anomalous increase of P -S value at the transition to the hexatic phases.