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 4-14-(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-mus 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.