Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 16: Organic, polymeric, biomolecular films - also with adsorbates

O 16.9: Talk

Monday, March 22, 2010, 17:00–17:15, H46

Growth of alpha-Sexithiophene films on Cu(110)-(2x1)O at elevated substrate temperatures — •Günther Weidlinger, Harald Zaglmayr, Lidong Sun, Daniel Roman Fritz, Thorsten Wagner, and Peter Zeppenfeld — Johannes Kepler Universität Linz, Institut für Experimentalphysik, Altenberger Straße 69, A-4040 Linz

alpha-Sexithiophene (6T) films were grown on the Cu(110)-(2x1)O surface in UHV with the substrate held at 380 K. Ex-situ atomic force microscopy (AFM), fluorescence microscopy (FM) and laser scanning confocal microscopy (LSCM) reveal elongated 6T islands with a height of up to a few hundred nanometers. These needles consist of crystallites of two distinct orientations with respect to the main axes of the substrate surface. However, polarization dependent FM shows that the 6T molecules in the needles are always aligned along the [001] direction of the substrate. Comparing AFM and FM images, regions of maximum fluorescence emission correspond to defects, e.g. needle ends or grain boundaries, at which light can couple out of the needles whereas defect-free parts appear darker due to a waveguiding effect inside the islands. Photoluminescence spectra obtained by LSCM are in qualitative agreement with reference spectra of single crystalline 6T. No wetting layer of 6T was observed with LSCM. This is in agreement with results from reflectance difference spectroscopy measurements where a quenching of the characteristic wetting layer signal was observed after exposure to air.