X-ray characterisation of local molecular orientation in the electroclinic effect of surface-stabilised SmA liquid crystals

Abstract

The local molecular orientation in the electroclinic effect of the chiral smectic A phase in a surface-stabilised cell has been determined using a time-resolved synchrotron X-ray microbeam diffraction technique. Space- and time-resolved X-ray wide-angle halo scattering under an electric field reveals the static and dynamic intralayer molecular orientation. The molecular orientation varies spatially in accordance with the stripe texture and is dependent on the applied voltage. It has been found that the deviation of the molecular orientation from the rubbing direction depends strongly on the sample history. The relation between the apparent molecular orientation and the layer structure is discussed.

Keywords:

• electroclinic effect
• chiral smectic A phase
• surface-stabilised cell
• X-ray microbeam
• time-resolved technique

Acknowledgements

The authors wish to thank the staff of the Photon Factory for their help during the experiments. The authors are also grateful for valuable discussions with Professor H. Takezoe, and to Ms Y. Ohtsuka for her help with the experiments.

This study was carried out under the approval of the Photon Factory Advisory Committee (Proposals 06G345 and 08G697). It was partially supported by Grant-In-Aid for Scientific Research (B) (18360013), the Ministry of Education, Science, Sports and Culture.