Dynamic Polarized Infrared Spectroscopy of Electric Field-Induced Molecular Reorientation in a Chiral Smectic-ALiquid Crystal

We report transient molecular orientation and conformation changes accompanying the electric field-induced soft mode molecular tilt in a chiral smectic- A liquid crystal. We exhibit directly the loss of uniaxial molecular symmetry with field-induced tilt, showing that the molecular tails are less tilted with respect to the layer normal than the cores, and during switching reach their equilibrium orientation later than the cores. We also find evidence for a collective mode of rotation about the molecular long axis.