Standardization of Chemically Selective Atomic Force Microscopy for Metal Oxide Surfaces.

Wiesener, Philipp; Förster, Stefan; Merkel, Milena; Schulze Lammers, Bertram; Fuchs, Harald; Amirjalayer, Saeed; Mönig, Harry · ACS Nano · 2024

basic_science · Level V

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Abstract

The structures of metal oxide surfaces and inherent defects are vital for a variety of applications in materials science and chemistry. While scanning probe microscopy can reveal atomic-scale details, elemental discrimination usually requires indirect assumptions and extensive theoretical modeling. Here, atomic force microscopy with O-terminated copper tips on a variety of sample systems demonstrates not only a clear and universal chemical contrast but also immediate access to the atomic configuration of defects. The chemically selective contrast is explained by purely electrostatic interactions between the negatively charged tip-apex and the strongly varying electrostatic potential of metal and oxygen sites. These results offer a standardized methodology for the direct characterization of even the most complex metal oxide surfaces, providing fundamental insight into atomic-scale processes in these material systems.