Submicrosecond Preliminary Process of Electric-Field-Induced Reorientation of a Ferroelectric Liquid Crystal, 5-(2-Fluoroalkoxy)-2-(4-n-Alkylphenyl)-Pyrimidine, Studied by Time-Resolved Infrared Spectroscopy

Abstract

Pulsed electric-field-induced reorientation of a ferroelectric liquid crystal (FLC), 5-(2-fluorooctyloxy)-2-(4-hexylphenyl)-pyrimidine, has been investigated by using a dispersive submicrosecond time-resolved infrared spectroscopic technique. The observed absorbance decay for a band at 1440 cm−1 due to a ring-stretching mode of the phenylpyrimidine group indicates that the FLC molecule reorients from a stationary state with a slight delay (less than 1 μs) just after the upswing of the electric field, while counter-reorientation occurs with a delay time of a microsecond after the reverse of the electric field. The delay time for the counter-reorientation changes with temperature, indicating that the viscosity has a strong influence on the delay time. It is also indicated in the present study that the whole FLC molecule reorients simultaneously as a rigid rod in both the preliminary and the counter-reorientation process.