Evidence for de Vries structure in a smectic-A liquid crystal observed by polarized Raman scattering.
The second- and fourth-order apparent orientational order parameters of the core part of the molecule P2 (app) and P4 (app) , have been measured by polarized vibrational Raman spectroscopy for a homogeneously aligned ferroelectric smectic liquid crystal with three dimethyl siloxane groups in the achiral terminal chain, which shows de Vries-type phenomena, i.e., very large electroclinic effect in the smectic- A (Sm-A) phase and a negligible layer contraction at the phase transition between the Sm-A and Sm- C(*) phases. The apparent orientational order parameters of the rigid core part of the molecule are extremely small both with and without the external electric field in Sm-A . These results provide evidence for the existence of the de Vries Sm-A phase, where the local molecular director is tilted at a large angle.
Hayashi
Naoki
N
Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan. naoki_a_hayashi@fujifilm.co.jp
Kato
Tatsuhisa
T
Fukuda
Atsuo
A
Vij
Jagdish K
JK
Panarin
Yuri P
YP
Naciri
J
J
Shashidhar
R
R
Kawada
Sachiko
S
Kondoh
Shinya
S