Helical Alignment of Field-Dependent Structures in Cholesteric Phase

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Abstract
The field-dependent structure in cholesteric phase has been investigated using several experiments. We have selected the azimuthal angle of a molecular layer ø and tilt angle in the direction of helical axis θ as the components of static deformation, and defined a new parameter as a degree of helical alignment by numerical value, Q = 2{1 – [(sin2 ø)]}[(cos2 θ)] = 2(1 − r)q. For perfectly helical alignment, Q = I, while for nematic state with helical alignment disappearing, Q = 0. The relation between these parameters and experimentally determined quantities, typical Q, and the method to measure the orientational order S in cholesterics using Q, were discussed.