Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: Poster: Interfaces and Thin Films

CPP 13.27: Poster

Tuesday, March 27, 2012, 18:15–20:45, Poster A

Switching properties and orientation of dichroic fluorescent dyes in a nematic liquid crystal — •Clemens Göhler, Harald Graaf, and Christian von Borczyskowski — TU Chemnitz, Institut für Physik

In a liquid crystal cell (LC-cell), the direction of the nematic phase director can be varied by applying an electric field [1]. It is also known that dichroic dye molecules may align with their long molecular axis parallel to the director. While illuminating the LC-cell, fluorescence emission intensity will change due to the applied field and the angle between the dye long molecular axis and its transition dipole moment [2]. By using both principles, a LC-cell with field induced colour switching should be realizable.

We investigate dye molecules that show shape anisotropy caused by long alkyl chains. Thus we manage both a collinear and perpendicular alignment to the transition dipole moment. Using (polarized) fluorescence emission spectroscopy the orientation and order parameter of the dyes within the nematic liquid crystal is determined.

[1] Williams, R.: J. Chem. Phys. 39, 384 (1963)

[2] Heilmeier, G.H, Zanoni, L.A.: Appl. Phys. Letters 13, 91 (1968)