Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Focus Session: Structure and Chemistry of Metal-Oxide Surfaces II
O 55.1: Vortrag
Mittwoch, 14. März 2018, 10:30–10:45, MA 005
Coverage-Dependent Water Agglomerates on Fe3O4(001): insights from theory — •Matthias Meier1,2, Jan Hulva1, Zdeněk Jakub1, Jiří Pavelec1, Martin Setvin1, Michael Schmid1, Ulrike Diebold1, Cesare Franchini2, and Gareth S. Parkinson1 — 1Institute of Applied Physics, Technische Universität Wien, Vienna, Austria — 2University of Vienna, Faculty of Physics and Center for Computational Materials Science, Vienna, Austria
Iron oxides are used in a wide range of applications in which their surfaces interact with water. Recent studies have found significant complexity with mixed-mode adsorption and coverage dependent hydrogen bonding. This study focuses on Fe3O4(001) and its interaction with water. Temperature programmed desorption (TPD) and non-contact atomic force microscopy (ncAFM) are combined with density functional theory (DFT) based calculations.
Quantitative TPD spectra reveals 4 distinct peaks for the desorption of the first monolayer of water, suggesting that stable configurations of water exist. Surfaces with the in the TPD relevant water coverages were prepared and studied in a CO functionalised tip ncAFM experiment. These results will be presented in a previous talk.
DFT predicts partially dissociated dimers and trimers located on Fe cations to be found to be the most stable configurations, in-line with the known concept of cooperativity. The ring-like networks observed in ncAFM, correspond to merged trimers which are connected via additional hydrogen bonded water molecules. The formation of these features is motivated by optimizing available hydrogen bonds.