Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 11: Metal & Semiconductor substrates: Adsorption and reaction of small molecules II
O 11.5: Talk
Monday, March 9, 2026, 16:00–16:15, HSZ/0401
Frontier Orbitals Control Adsorbate Bonding to Stepped Transition Metal Surfaces — •Florian Nitz1, Stefan Hörandl1, Dmitriy Borodin2, and Alec Wodtke1 — 1Institute for Physical Chemistry, Georg-August University of Goettingen, Tammannstraße 6, 37077 Goettingen, Germany — 2Center for Quantum Nanoscience (QNS), Institute for Basic Science (IBS), Seoul 03760, South Korea
Developing intuitive models of bonding and reactivity lies at the heart of physical chemistry. While such models have been developed for atoms and molecules, we still lack concepts to explain bonding and reactivity in the solid state, including surface chemistry and catalysis. Here, we address this gap and present a model of covalent bonding between molecular orbitals of an adsorbate and symmetry-specific bands on a metal surface atom, analogous to frontier orbital theory in molecular chemistry. We apply the model to the adsorption of three molecules–CO, NO, and NH3–on stepped platinum surfaces of varying step density and compare its predictions to experimental adsorption energies. The experiment reveals that the adsorption energies vary systematically with step density, an unexpected phenomenon that can only be explained by the frontier orbital model. Correlations of the adsorbate bond strength with the mean energy of the metal d-electrons or with surface strain fail to describe the experimental observations. This highlights frontier orbitals as a powerful concept to rationalize bonding and reactivity in condensed-phase systems.
Keywords: Adsorption of Small Molecules on Metal Surfaces; Surface Reaction Kinetics; Electronic Structure; Density Functional Theory