Selective Reflection of a Chiral Smectic C Phase and a Cholesteric Phase

Abstract Reflection spectra were measured with obliquely incident light for a chiral smectic C phase and a cholesteric phase of (+)-4-n-hexyloxyphenyl 4-(2″-methylbutyl)biphenyl 4'-carboxylate. Spectra with plane-polarized light revealed that the characteristics of spectra, previously computed by Berreman, were essential features of the two different liquid crystal phases in the case of oblique incidence. A full pitch band appeared at about twice the wavelength of a "normal" band for the chiral smectic C but not for the cholesteric. The full pitch band was found to be composed almost only of σπ- and πσ-bands for any incident angle. The relative intensity, and the peak position of polarized components of the normal bands agreed qualitatively with those of the computed spectra for the chiral smectic C phase as well as for the cholesteric phase.