PA35 ^<13>C-NMRと高周波誘電測定によるキラルスメクティック液晶相における分子運動の研究(物理・物性)

概要

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The molecular dynamics in some chiral smectic phases is studied by means of the solid-state ^<13>C-NMR spectroscopy and the high frequency dielectric measurements. The samples used are an antiferroelectric liquid crystal (S)-MHPOBC and a ferroelectric liquid crystal (S)-DOBAMBC. In ^<13>C-NMR measurements of (S)-MHPOBC, the spin-lattice relaxation time T_1 of the phenyl core part has a minimum at the temperature region of SmC_A^* in its temperature dispersion curve. Since the Ti minimum occurs at ω_0τ_c〜1, the correlation time (τ_c) of the molecular motion, which is to correspond to the molecular rotation around its long axis, could be estimated at about 10^<-8>sec. The activation energy of the molecular motion of phenyl core part in SmC_A^* estimated by the NMR measurements is larger than that in SmA, because of the stronger hindrance of the molecular rotation in SmC_A^*. As for (S)-DOBAMBC, the temperature dependence of T_1 shows that the activation energy in SmA is larger than in SmC^* for most of the carbon nuclei.
日本液晶学会の論文
2002-10-09