Time-resolved X-ray micro-diffraction of the dynamic local layer response to electric field in antiferroelectric liquid crystals

The local layer structure response to the ac electric field in an antiferroelectric liquid crystal cell has been measured using synchrotron X-ray diffraction with less than ms time resolution and a few μm spatial resolution. The initially coexisting vertical and horizontal chevron structures are irreversibly transformed to the layer structure with a rearranged molecular orientation at the surface. After the irreversible transition, the rearranged layer structure shows a reversible transition between the horizontal chevron (ferroelectric state) and the combination of the vertical and horizontal chevron (antiferroelectric state). The stripe texture is related to the modified horizontal chevron structure. The transient response time of the layer deformation is ca. 0.1 ms and is close to the optical response time. Compared with the ferroelectric liquid crystal response, the effect of the field induced phase transition of the antiferroelectric liquid crystal is discussed. (author)