Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Organic/bio Molecules on Metal Surfaces II
O 18.4: Vortrag
Montag, 11. März 2013, 16:45–17:00, H38
Spatial distribution of molecular orbitals from angle-resolved photoemission — •Daniel Lüftner1, Thomas Ules1, Eva Maria Reinisch1, Georg Koller1, Sergey Soubatch2, F. Stefan Tautz2, Michael G. Ramsey1, and Peter Puschnig1 — 1Institut für Physik, Karl-Franzens-Universität Graz, Austria — 2Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Germany
The frontier electronic orbitals of molecules are the prime determinants of the respective compounds' chemical, electronic, and optical properties. Several experimental methods have enabled imaging of molecular orbitals under certain conditions. As has been shown in a number of recent publications, angle-resolved photoemission (ARPES) intensity maps of organic molecular layers are related to the Fourier transform of the initial state molecular orbital. However, the missing phase information impedes the back-transformation of the momentum maps of the orbital into real space. Here, we show how the absent phase information can be retrieved by applying an unbiased, iterative procedure which takes the experimental ARPES maps as input and only assumes spatial confinement of the orbital. Thereby we obtain real-space images of several molecular orbitals for two proto-typical pi-conjugated molecules: the LUMO, HOMO, and HOMO-1 of pentacene, and the LUMO and HOMO of PTCDA. Our technique further emphasizes the capabilities of ARPES looking at spatial distributions of wave functions of adsorbed molecules thereby complementing data obtained from scanning probe methods.