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.

Complex dielectric constant of an antiferroelectric liquid crystal family represented by 4-(1-methylheptyloxycarbonyl) 3-fluorophenyl 4'-dodecylbiphenyl-4-carboxylate was measured in the frequency range between 10-2 Hz and 107 Hz. The experimental results were analyzed using a generalized Cole-Cole expression, and seven dielectric relaxation modes were confirmed to exist. Possible models of collective molecular motions are proposed for mode assignments on the basis of the experimental results of temperature dependence of the modes, together with those of cell gap and bias field dependences.