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O: Fachverband Oberflächenphysik

O 62: Posters: Surface Reactions and Dynamics, Nanostructures

O 62.26: Poster

Mittwoch, 2. April 2014, 17:30–21:00, P1

Simulation of angle-resolved photoemission cross-sections for organic/metal interfaces — •Dario Knebl, Daniel Lüftner, Bernd Kollmann, and Peter Puschnig — Karl-Franzens-Universität Graz, Institut für Physik

Several combined experimental / theoretical investigations have demonstrated a close relation between the angle-resolved photoemission (ARPES) intensity of oriented organic molecular films and the Fourier transform of the molecular orbital. So far, experimental ARPES data has been accounted for by neglecting the interaction of molecule with the underlying metal substrates. The remaining small differences have been tentatively attributed to modifications of the molecular states due to molecule-substrate hybridization, though alternative explanations, e.g., light polarization effects or the failure of the simple plane-wave final state approximation could not be excluded. Here we calculate ARPES intensity maps for the prototypical PTCDA/Ag(110) interface by explicitly considering molecule-substrate interactions within ab-inito density functional calculations. In order to take into account the free mean path of photo-emitted electrons, we modify the final state plane wave by introducing an exponential decay term of the final state. We perform careful convergence studies with respect to the number of metallic layers and the number of k-points, and compare our results to ARPES measurements. Thereby, we shed light on the molecule-metal hybridization and reveal limitations of the plane-wave final state approximation for such molecular films.