Quantifying the evolution of atomic interaction of a complex surface with a functionalized atomic force microscopy tip

Alexander Liebig*, Prokop Hapala, Alfred J. Weymouth, Franz J. Giessibl

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)
11 Downloads (Pure)

Abstract

Terminating the tip of an atomic force microscope with a CO molecule allows data to be acquired with a well-known and inert apex. Previous studies have shown conflicting results regarding the electrostatic interaction, indicating in some cases that the negative charge at the apex of the CO dominates, whereas in other cases the positive charge at the end of the metal tip dominates. To clarify this, we investigated CaF 2(111). CaF 2 is an ionic crystal and the (111) surface does not possess charge inversion symmetry. Far from the surface, the interaction is dominated by electrostatics via the negative charge at the apex. Closer to the surface, Pauli repulsion and CO bending dominate, which leads to an unexpected appearance of the complex 3-atom unit cell. We compare simulated data in which the electrostatics are modeled by point particles versus a charge density calculated by DFT. We also compare modeling Pauli repulsion via individual Lennard–Jones potentials versus a total charge density overlap. In doing so, we determine forcefield parameters useful for future investigations of biochemical processes.

Original languageEnglish
Article number14104
Pages (from-to)1-12
Number of pages12
JournalScientific Reports
Volume10
Issue number1
DOIs
Publication statusPublished - 1 Dec 2020
MoE publication typeA1 Journal article-refereed

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