Eur. Phys. J. E 3, 273-281
Optical rotatory power in tilted smectic phases
F. Beaubois - J.P. Marcerou - H.T. Nguyen - J.C. Rouillon
Centre de Recherches Paul Pascal, CNRS-UPR8641, Av. A.
Schweitzer, 33600 Pessac, France
Received 7 January 2000 and Received in final form 7 April 2000
Optical Rotatory Power measurements have been done on different chiral tilted smectics which lead to reproducible results. The high-temperature uniaxial SmA and SmC phases do not show any ORP due to the lack of in-plane anisotropy at the mesoscopic level (i.e. a few layers). At lower temperature one gets the synclinic C* and the anticlinic CA* phases with a helical precession around the layer normal which is right-handed for C* and left-handed for CA* . These phases are separated in a finite temperature range by a set of two so-called "ferrielectrics'' SmCFi1* and SmCFi2*, which are not necessarily new phases, between which the handedness changes sign at a given temperature, while the change from synclinic to anticlinic tilt angle organization is spread out over the "ferrielectric'' temperature range. In order to reconcile all experimental observations, otherwise apparently incompatible, it is proposed that the "ferrielectric'' region is a diphasic one where the in-plane organization changes smoothly from the synclinic type to the anticlinic one.
64.70.Md Transitions in liquid crystals - 78.20.Ek Optical activity
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