Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 7: Metal substrates: Adsorption of organic / bio molecules I
O 7.1: Vortrag
Montag, 26. März 2012, 10:30–10:45, A 053
(contribution withdrawn) Order or disorder? The adsorption of NTCDA on Ag(111) investigated by VT-STM — •Holger Wetzstein1,2, Sebastian Fiedler1,2, Jeremias Weinrich1,2, Martin Winnerlein1,2, Achim Schöll1,2, and Friedrich Reinert1,2 — 1Physikalisches Institut, Experimentelle Physik VII und Wilhelm Conrad Röntgen Research Center for Complex Material Systems (RCCM), Universität Würzburg, D-97074 Würzburg — 2Gemeinschaftslabor für Nanoanalytik, Karlsruher Institut für Technologie KIT, D-76021 Karlsruhe
The adsorption of organic molecules on single crystalline substrates results in a wealth of structural arrangements. This polymorphism is due to the interplay between lateral and vertical interactions and strongly depends on coverage, temperature and preparation. We investigated the adsorption of NTCDA on Ag(111) surfaces at different temperatures with the help of variable temperature scanning tunneling microscopy and low energy electron diffraction to analyze the structural and electronic properties. This systems shows various adsorbate superstructures and a particularly interesting reversible order-disordering transition upon cooling, so called inverse melting. While some thermodynamic parameters of this transition have already been derived, the driving force for this ordering phenomenon as well as the geometric arrangement of the molecules in the disordered phase has not yet been accessed. Our STM data shows various ordered and disordered structural phases at different temperatures. By correlating our new results with already existing data we intend to shed light on the mechanism involved in the ordering of organic molecules on metal substrates.