DYNAMIC POLARIZED INFRARED-SPECTROSCOPY OF ELECTRIC-FIELD-INDUCED MOLECULAR-REORIENTATION IN A CHIRAL SMECTIC-A LIQUID-CRYSTAL

We report transient molecular orientation and conformation changes acc ompanying the electric field-induced soft mode molecular tilt in a chi ral smectic-il liquid crystal. We exhibit directly the loss of uniaxia l molecular symmetry with held-induced tilt, showing that the molecula r tails are less tilted with respect to the layer normal than the core s, and during switching reach their equilibrium orientation later than the cores. We also find evidence for a collective mode of rotation ab out the molecular long axis.