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
marcerou@crpp.u-bordeaux.fr
Received 7 January 2000 and Received in final form 7 April 2000
Abstract
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.
PACS
64.70.Md Transitions in liquid crystals -
78.20.Ek Optical activity
Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag
