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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: Liquid Crystals and Polar Fluids

CPP 3.1: Vortrag

Montag, 25. Februar 2008, 10:00–10:15, C 264

Controlling Size and Arrangement of Smectic Focal Conic Domains — Wei Guo, Yasutaka Iwashita, Stephan Herminghaus, and •Christian Bahr — MPI for Dynamics and Self-Organization, Bunsenstr. 10, 37073 Göttingen

Defect structures in liquid crystals are of interest from both fundamental and applied viewpoints. For instance, topological defects can lead to the self-assembly of two-dimensional nematic colloidal crystals [1].

The present study is concerned with defect structures in smectic liquid crystals, so-called focal conic domains, which consist of a complex arrangement of curved equidistant molecular smectic layers which are wrapped around two singular lines. We describe a method to generate almost arbitrary two-dimensional arrangements of focal conic domains in smectic films. The method is based on the patterning of a silicon substrate with a thin gold layer that is evaporated through a lithographic mask. In smectic films on such substrates, the generation of focal conic domains is confined to the masked areas so that both the size of individual domains and the overall arrangement of many domains can be controlled. We study the generated structures on linearly and circularly patterned substrates by optical, fluorescence confocal, and scanning force microscopy [2], and discuss the use of focal conic domains as matrices for self-assembling microsystems.

[1] I. Muševič, M. Škarabot, U. Tkalec, M. Ravnik, and S. Žumer, Science 313, 954 (2006).

[2] V. Designolle, S. Herminghaus, T. Pfohl, and Ch. Bahr, Langmuir 22, 363 (2006).