Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 9: Oxides and Insulators: Adsorption I

O 9.2: Talk

Monday, March 26, 2007, 11:30–11:45, H42

Force controlled lateral manipulation of water adsorbed on CaF₂(111) — •Sabine Hirth, Frank Ostendorf, and Michael Reichling — Universität Osnabrück, Fachbereich Physik, Barbarastraße 7, 49076 Osnabrück

We demonstrate for the first time the force controlled manipulation of a molecular adsorbate on an insulating substrate. We show that physisorbed water can be manipulated along three principal symmetry directions of CaF₂(111). Imaging and manipulation of water molecules is accomplished by scanning the surface at different tip-surface-distances. During manipulation steps, the movement of the molecules results in characteristic chain-like features along the slow scanning direction having a periodicity of the CaF₂ surface lattice. The form of the profiles can be assigned to a pushing type interaction. The movement of the molecule from one position to another is instantaneous on the time scale of the measurement leading to a jump of the defect position within certain scan lines. Complicated scanning profile forms result from the manipulation of defect groups. We describe the manipulation protocol in detail, explain the manipulation mechanism and discuss possible improvements for the manipulation.