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O: Fachverband Oberflächenphysik

O 14: Organic, polymeric, biomolecular films – also with absorbates I

O 14.2: Talk

Monday, March 23, 2009, 15:15–15:30, SCH A316

Stranski-Krastanov growth of Sexithiophene and para-sexiphenyl on Cu(110)-(2x1)O — •Lidong Sun¹, Günther Weidlinger¹, Mariella Denk¹, Richard Denk¹, Michael Hohage¹, Peter Zeppenfeld¹, Stephen Berkebile², Georg Koller², Falko.P. Netzer², and Michael.G. Ramsey² — ¹Institute of Experimental Physics, Johannes Kepler University Linz, Austria — ²Institute of Physics, Karl-Franzens University Graz, Austria

The initial stage of Sexithiophene (6T) and para-sexiphenyl (p-6P) growth on Cu(110)-(2x1)O has been investigated by in-situ reflectance difference spectroscopy (RDS) and scanning tunneling microscopy (STM). For both organic molecules, the optical response of the thin films shows a strong anisotropy indicates that the molecules are lying down on the surface with their long axis parallel to the [001] direction of the Cu(110) surface. Furthermore, the RD spectra of the growing films reveal systematic changes with increasing of film thickness reflecting a clear evolution of the absorption spectrum from a single molecule like to molecular crystal exciton. The observed evolution of the optical anisotropy also clearly shows that both 6T and p-6P thin films follow a Stranski-Krastanov growth mode with two ML thick wetting layers. Corresponding STM investigation on the morphology of 6T and p-6P thin films of up to two monolayers confirms the conclusion deduced from RDS results.