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Updated: May 13, 2026

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Azimuthal reorientation of pentacene upon 2D condensation
L D Sun1, J Gall, G Weidlinger
1Institute of Experimental Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria. lidong.sun@jku.at
Abstract:
We report a novel two-dimensional gas-solid phase transition of pentacene molecules on the Cu(110)-(2 × 1)O surface where the 2D condensation is accompanied by a reversible azimuthal rotation of the pentacene molecules. The change of the optical anisotropy associated with this reorientation allows us to explore the 2D condensation as a function of coverage and temperature by reflectance difference spectroscopy. As a result, the 2D heat of condensation of pentacene on Cu(110)-(2 × 1)O is determined to be 84 meV, which is more than one order of magnitude smaller than the respective value for 3D crystallization.
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