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O: Fachverband Oberflächenphysik

O 98: Metal and Semiconductor Substrates: Adsorption and Reactions of Small Molecules

O 98.1: Vortrag

Freitag, 21. März 2025, 10:30–10:45, H8

Bonding properties of a CO molecule with metallic adatoms — •Fabian Stilp, Marco Weiss, Maximilian Krüger, and Franz J. Giessibl — Department of Physics, University of Regensburg

CO terminated AFM tips are often used to investigate molecules on surfaces as they are a powerful tool to make the internal structure of such molecules visible. Their chemical inertness results in high resolution of the single atoms and bonds in such molecule via Pauli repulsion. However, it was shown by Huber et al. [1] that CO terminated tips can form weak bonds to some species of adatoms on a Cu (111) sample such as Fe and Cu as evident by an attractive center within a repulsive ring in constant height AFM measurement. In contrast, Si adatoms only interact via van der Waals attraction and Pauli repulsion.

Can one predict the strength of the bond between the CO molecule and an arbitrary atom just from its electron configuration? To set the rules for this prediction we expand our collection of AFM measurements on various adatoms by adding Ni and Ag.

Ni has a partially filled d-shell and thus forms a chemical bond of similar strength as Fe. Surprisingly, Ag with its similar electron configuration as Cu, immediately goes to Pauli repulsion while Cu first forms a weak bond.

[1] Huber et al., Science 366, 235-238 (2019).

Keywords: single atom; CO; reactivity; AFM; catalysis