Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 12: Nanostructures at Surfaces I

O 12.5: Talk

Monday, March 17, 2025, 16:00–16:15, H6

Artificial Atoms: Energy-Level Engineering and Shape-Dependent Reactivity — •Marco Weiss, Fabian Stilp, Michael Roessner, Max Reinhart, and Franz J. Giessibl — Institute of Experimental and Applied Physics, University of Regensburg

Artificially arranged nanostructures can confine the quasi-free two-dimensional electron gas present on noble metal surfaces, giving rise to a series of resonant eigenstates [e.g. 1-3]. These structures, often referred to as artificial atoms, exhibit remarkable parallels to natural atoms, including the ability to form chemical bonds with natural atoms or repulsive interactions with chemically inert molecules. [4] In our previous investigations using atomic force microscopy (AFM), we successfully identified the occupation of resonant eigenstates that intersect the Fermi level. Notably, we observed a probe-tip-induced energy shift of these states during the measurements. [4] Building on these findings, we developed a method to estimate the energy of artificial atomic states based on their electron occupation. This approach enables precise tuning of the energy levels of these states with meV-scale accuracy. Additionally, we discovered that the distance-dependent repulsive interaction between a chemically inert molecule and the resonant eigenstates of the artificial atom is influenced by the geometric shape of the nanostructure. This holds the potential to tailor nanoscale interactions through precise structural design. [1] Crommie et al., Science 262 (1993), [2] Manoharan et al., Nature 403 (2000), [3] Freeney et al., SciPost Phys. 9 (2020), [4] Stilp et al., Science 372 (2021)

Keywords: quantum corral; AFM; attraction; occupation; nanostructure