Mechanical and Chemical Interactions in Atomically Defined Contacts

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 17; no. 35; pp. e2101637 - n/a
• Main Authors: Yesilpinar, Damla, Schulze Lammers, Bertram, Timmer, Alexander, Hu, Zhixin, Ji, Wei, Amirjalayer, Saeed, Fuchs, Harald, Mönig, Harry
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.09.2021
• Subjects: Adatoms; atom manipulation; Atomic force microscopy; Atomic interactions; functionalized tips; Nanotechnology; non‐contact atomic force microscopy; Tips; Xenon
• DOI: 10.1002/smll.202101637
• ISSN: 1613-6810; 1613-6829

Providing fundamental insights in atomic interactions, dedicated methods in atomic force microscopy allow measuring the threshold forces needed to move single adsorbed atoms or molecules. However, the chemical and structural properties of the probe‐tip can drastically influence the results. Establishing atomically defined contacts in such experiments, the tips in the present study are functionalized with various chemically and structurally different terminations. Xenon atoms are moved along an atomically defined metal/metal‐oxide boundary where all tips show a pulling mechanism and slight force variations, which are assigned to polarization effects within the tip‐sample junction. Detaching Xe atoms from the boundary involves a significantly higher energy barrier where chemical reactive Cu‐tips cause Xe pickup before any lateral manipulation. Passivating the tip by inert probe particles (Xe or CO) allows further approaching the surface Xe atom. Yet, the small vertical attraction and pronounced tip relaxations prevent reaching sufficient threshold forces inducing manipulation. In contrast, the high structural rigidity of oxygen‐terminated Cu‐tips allows manipulations even beyond the threshold where they evolve from initial pulling, via sliding to pushing mode. The detailed quantitative analysis of the processes in the atomically defined junctions emphasizes the mechanical and chemical interactions for highly controlled experiments with piconewton sensitivity. The authors directly compared the performances of four different tip terminations in non‐contact atomic force microscopy manipulation experiments on single Xe atoms adsorbed at the metal/metal‐oxide boundary on partially oxidized Cu(110) surface. The results show how the chemical reactivity and the mechanical stability of the tip terminating particles can be determinative on the outcome of the manipulation processes.