Time-Resolved FT-IR Study on Reorientation of Ferroelectric Liquid Crystal, (S)-4-Methylhexyl 4-[4-(Decyloxy) Phenylethynyl]-2-Fluorobenzate

The electric-field-induced reorientation of (S)-4-methylhexyl 4-[4-(decyloxy) phenylethynyl]-2-fluorobenzate in the S c * phase was investigated by using an asynchronous time-resolved FT-IR technique. The band assignments were made on the basis of the polarized FT-IR spectra and FT-Raman spectrum. The time-resolved study indicates that the reorientation occurs immediately after the electric field is applied. The molecule reorients as a unit; however the rigid core of the molecule seems to be more mobile than the hydrocarbon chains and needs a shorter period of time for the reorientation. The change of orientation is not completely finished in a 500-μs time period. Of particular note is the behavior of the carbonyl band; this band, usually strong in infrared spectra, is very weak in the time-resolved spectra.