Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 9: Nanotribology

O 9.9: Vortrag

Montag, 11. März 2013, 12:30–12:45, H42

The effect of tip force field symmetry on atomic manipulation — •Matthias Emmrich, Maximilian Schneiderbauer und Franz J. Giessibl — Institute of Experimental and Applied Physics, Universität Regensburg, 93040 Regensburg, Germany

In the last years, significant progress has been made in understanding the manipulation of adatoms on atomically flat surfaces by scanning probe microscopy. Pushing, pulling and sliding atomic manipulation modes have been identified [L. Bartels et al., PRL 1997]. Moreover, the forces that act during manipulation have been measured [M. Ternes et al., Science 2008]. In the first demonstration of atomic manipulation by Eigler and Schweizer [M. Ternes et al., Science 2008], van-der-Waals forces have been identified to allow the lateral manipulation of Xe on Ni (110). Van-der-Waals forces only depend on distance, but in later experiments involving metallic adatoms, metallic bonding was expected to contribute. Recently, a strong angular dependence of these short-range bonding forces has been measured [J. Welker and F.J. Giessibl, Science 2012].
In this study we investigate the influence of the symmetry of the tip’s force field on the lateral manipulation of a CO molecule over a Cu(111) surface. The symmetry of the tip is determined using the COFI (carbon oxide front atom identification) method recently introduced by Welker and Giessibl. Lateral forces are extracted from line scans over the CO molecule at different heights. These forces were evaluated not only for different tip symmetries, but also as a function of the direction of manipulation.