Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 35: Organic-inorganic hybrid systems and organic films IV

O 35.5: Talk

Tuesday, March 13, 2018, 15:00–15:15, MA 042

Orbital Imaging of Non-Planar Molecules Beyond the Free Electron Finalstate Approximation — •Christian Metzger, Manuel Grimm, Martin Graus, Achim Schöll, and Friedrich Reinert — Julius-Maximilians-Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany

It has been shown that the imaging of molecular orbitals is possible by angle-resolved photoelectron spectroscopy (ARPES). For planar aromatic molecules the approximation of the photoemission final state by a simple plane wave allows for a particularly straightforward interpretation of the experimental data. Here we present a combined experimental and theoretical study on the angular intensity distribution of photoelectrons from non-planar molecules. The ARPES data of a single layer of C60 on Ag(110) was acquired by a momentum microscope which enables the efficient detection of photoelectrons emitted into the entire hemisphere above the sample. The symmetry of the recorded photoelectron momentum maps (PMM) immediately demonstrates that the molecules adsorb with a single specific alignment and do not rotate even at room temperature. On the theoretical side, a simple plane-wave approximation of the finalstate is bound to fail due to the 3D geometry of C60. A more suitable description can be realized within the framework of independent atomic centers (IAC), where the finalstate can be assembled by the composite contributions of the individual atoms inside the molecule. We demonstrate that this IAC approach provides a very good simulation of the experimental PMM and thus allows the assignment of different initialstate orbitals.