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

Pulsed electric-field-induced reorientation of a ferroelectric liquid crystal (FLC), 5-(2-fluorooctyloxy)-2-(4-hexylphenyl)-pyrimidine has b een investigated by using a dispersive submicrosecond time-resolved in frared spectroscopic technique, The observed absorbance decay for a ba nd at 1440 cm(-1) due to a ring-stretching mode of the phenylpyrimidin e group indicates that the FLC molecule reorients from a stationary st ate with a slight delay (less than 1 mu s) just after the upswing of t he electric field, while counter-reorientation occurs with a delay tim e of a microsecond after the reverse of the electric field, The delay time for the counter-reorientation changes with temperature, indicatin g that the viscosity has a strong influence on the delay time, It is a lso indicated in the present study that the whole FLC molecule reorien ts simultaneously as a rigid rod in both the preliminary and the count er-reorientation process.