Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 10: Metal substrates: Adsorption of organic / bio molecules II
O 10.7: Vortrag
Montag, 14. März 2011, 16:30–16:45, TRE Phy
α-sexithiophene on silver: The influence of the surface miscut — •Thorsten Wagner, Daniel Roman Fritz, and Peter Zeppenfeld — Institute of Experimental Physics at the Johannes Kepler University Linz, Austria
The growth of α-sexithiophene (α-6T) on Ag(110) and Ag(441) was studied by means of scanning tunneling microscopy (STM) and photoelectron emission microscopy (PEEM). In contrast to (110) surfaces of other metals, α-6T molecules deposited on Ag(110) do not align exclusively along the close-packed atomic troughs but also perpendicular to them. The mixture of molecules arranged with their long axis parallel to the [001] and [110] directions lead to strained checkerboard pattern as described by Yokoyama.1 Besides the checkerboard phase, a well ordered homochiral phase was found. STM images show that although the molecules in the second layer are exclusively aligned in the [001] direction their arrangement is strongly influenced by the perpendicular molecules of the first layer. By using a Ag(441) surface, the molecules of the first layer can be forced to align exclusively along the [110] direction. In this case, the molecules are parallel to the steps of the substrate. In addition, step bunching and faceting of the vicinal substrate surface was found upon adsorption of α-6T. For more than two monolayers of α-6T deposited on both, the Ag(110) and the Ag(441) surface, a 3D growth was observed by PEEM. The PEEM intensity curves recorded during film growth provide additional details on the complex growth of the molecules on both surfaces.
[1] T. Yokoyama, Applied Physics Letters 96, 063101 (2010)