抄録
Because the rotation around the molecular long axis plays an important role for the emergence of ferroelectricity in chiral smectic liquid crystalline materials, many investigations have been performed to clarify it. As for the dynamical aspect, however, the detail of the hindered molecular rotation is still open for the question, though several experimental approaches have carried out so far. In this report, we study molecular dynamics of chiral and achiral smectic liquid crystals, analyzing the ^<13>C spin-lattice relaxation time (T_1) and the half-width (H-W) of ^<13>C-NMR resonance peaks, which are estimated by means of solid-state ^<13>C-NMR spectroscopy with Larmor frequency ω_0 of 100MHz. The chiral and achiral smectic samples used are S-4-(1-methylhexyloxycarbonyl)phenyl 4'-octyloxy-biphenyl-4-carboxylate (S-MH(6)POBC) and 4-(hexyloxycarbonyl)phenyl-4'-octyloxybiphenyl-4-carboxylate (H(6)POBC), respectively. Temperature dependence of T_1 and H-W is measured in order to detect changes of their molecular rotation during the successive phase transformations.
