Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 79: Electronic Structure of Surfaces: Spectroscopy, Surface States I
O 79.2: Vortrag
Mittwoch, 22. März 2017, 15:30–15:45, WIL C307
Photoemission tomography from extended 2D layers: the role of molecule/substrate interactions — •Peter Puschnig1, Daniel Lüftner1, Thomas Ules1, Georg Koller1, Xiaosheng Yang2, Simon Weiß2, Vitaliy Feyer3, Stefan Tautz2, Michael Ramsey1, and Sergey Soubatch2 — 1Institute of Physics, University of Graz, Austria — 2Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Germany — 3Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, Germany
The valence band photoemission angular distribution (PAD) from highly oriented organic molecular layers has been shown to contain rich information on the spatial structure of orbitals and thereby also allows molecular orientations and conformations to be determined. In the past however, measured PADs have been often interpreted in terms of molecular orbitals computed for gas phase molecules.
In this contribution, we show how the photoemission tomography approach can be generalized to take into account two-dimensionally extended organic layers which are in contact with a substrate surface. To this end, we extend the initial state to a sum over Bloch states within the first Brillouin zone and further modify the plane wave final state such that the mean free path of the photoelectron is taken into account in an empirical manner. With the example of a monolayer of PTCDA on Cu(100) a detailed comparison of simulated and experimental momentum and band maps is then made which demonstrates show how the large substrate mediated intermolecular dispersion manifests itself.