SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 73: Metal Substrates: Adsorption and Reaction of Small Molecules II
O 73.8: Vortrag
Donnerstag, 30. März 2023, 12:15–12:30, CHE 91
Bromine on Rh(111) - A combined XPS and LEED study — •Eva Marie Freiberger1, Natalie J. Waleska1, Anton Harrer1, Felix Hemauer1, Valentin Schwaab1, Hans-Peter Steinrück1, and Christian Papp1,2 — 1Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany — 2Freie Universität Berlin, Berlin, Germany
The adsorption of halogens on metals is a fundamental question in surface science. Detailed knowledge in this regard is of interest for any processes on surfaces, in which halogens are involved as a reactant or by-product. This plays a role, for example, in electrochemistry, when the electrolyte adsorbs at the electrodes, or in on-surface synthesis, which often relies on coupling reactions with halogens as the leaving group, leading to their accumulation on the surface.
We investigated the adsorption and thermal evolution of elemental bromine on the Rh(111) single-crystal surface by synchrotron radiation-based high-resolution X-ray photoelectron spectroscopy (XPS), temperature-programmed XPS, and low energy electron diffraction (LEED). The adsorption of bromine on Rh(111) held at 170 K was followed in situ by XPS, revealing a coverage-dependent shift in the Br 3d spectra. Using LEED as a complementary method, we propose that the observed shift is caused by different bromine superstructures on Rh(111): a (√3 x √3)R30∘ structure for lower coverages and a compression structure for saturation coverage. Subsequent heating shows a quite high temperature stability of bromine on Rh(111) up to 925 K, indicating covalent bonding.