SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 81: Oxide and Insulator Surfaces I: Adsorption and Reaction of Small Molecules
O 81.4: Vortrag
Donnerstag, 30. März 2023, 15:45–16:00, CHE 91
Fe3O4(111): surface structure and CO adsorption — •Johanna Hütner1, Florian Kraushofer1, Matthias Meier1,2, Zdenek Jakub3, Cesare Franchini2,4, Michael Schmid1, Ulrike Diebold1, Gareth S. Parkinson1, and Jan Balajka1 — 1Institute of Applied Physics, TU Wien, Austria — 2Computational Materials Physics, University of Vienna, Austria — 3CEITEC, Brno University of Technology, Czech Republic — 4Department of Physics and Astronomy, Università di Bologna, Italy
The surface structure of Fe3O4(111) has been the subject of an ongoing debate. The most stable termination, over a wide range of oxygen chemical potentials, has a layer of tetrahedrally coordinated iron atoms (Fetet1). We present AFM data that show an almost perfect grid of Fetet1 atoms. In filled states STM images, iron atoms exhibit varying contrast, suggesting electronic structure variations among the cation sites. We study the adsorption of CO as a probe molecule on the Fe3O4(111) surface with noncontact AFM. The data show that CO adsorbs on top of Fetet1 atoms at all coverages. We identify coverage-dependent adsorption structures with varying CO–CO spacings. We propose that the apparent CO–CO repulsion is a substrate-mediated effect that could be explained by charge redistribution in the surface. The CO ordering on a defect-free Fe3O4(111) surface is consistent with previously measured temperature programmed desorption data. Our findings contribute to the understanding of the electronic structure of the Fe3O4(111) surface and will be a requisite for modeling the adsorption of more complex molecules.