Polarized infrared spectroscopic study on hindered rotation around the molecular axis in the smectic-C* phase of a ferroelectric liquid crystal with a naphthalene ring. Application of two-dimensional correlation spectroscopyto polarization angle-dependent spectral variations

Polarization angle-dependent infrared spectra of a ferroelectric liquid cry stal with a naphthalene ring in the smectic-C* phase were measured at 60 de grees C under de voltage of 40 V with positive and negative polarity for in vestigating the relative orientation of the alkyl chain, mesogen, and chira l segments. The obtained polarization angle-dependent infrared spectra were analyzed by two-dimensional (2D) correlation spectroscopy. The 2D correlat ion analysis clearly detects slight phase differences in the polarization a ngle dependence which are hardly recognized by ordinary plots of intensity changes in infrared bands. It has been revealed from the 2D correlation ana lysis that not only the two carbonyl groups, but also other parts of molecu le, carry out hindered rotations about the long molecular axis. The 2D corr elation analysis also allows us to separate a CH3 asymmetric stretching ban d due to the chiral methyl group from those arising from other methyl group s. The C=O stretching bands due to the carbonyl group in the chiral part ar e also separated by 2D correlation spectroscopy into two bands. which may a rise from the rotational isomerism around the O-C axis of the chiral part.