Investigations of orientational order for an antiferroelectric liquid crystal by polarized Raman scattering measurements.
The orientational ordering of the antiferroelectric liquid crystal molecules, 4-(1-methyl-heptyloxycarbonyl)phenyl 4(')-octyloxybiphenyl-4-carboxylate was investigated in the series of the successive smectic phases by means of polarized Raman scattering measurement without any external field. An improved equation for the analysis of the polarized Raman intensity was derived as a function of an incident laser polarization and the orientational order parameters. Even in the chiral smectic phases, some apparent orientational order parameters could be defined by the proper corrections for the smectic layer structure and an optical disturbance. An unusual change of the orientational order parameters was observed with decrease in temperature. It was concluded that the irregular variation of the order parameter stemmed from the biaxiality of the molecular orientational distribution, which was attributed to the hindrance of molecular rotation around its long axis.
Hayashi
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Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan.
Kato
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