Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 17: Poster Session I (Nanostructures at Surfaces; Metal Substrates: Epitaxy and Growth; Methods: Scanning Probe Techniques; Phase Transitions)
O 17.42: Poster
Montag, 26. März 2007, 17:30–20:30, Poster C
Force Interactions in Atomically Defined Tip-Sample Contacts — •D. Braun1, J. Falter1, A. Schirmeisen1,3, H. Hölscher3, U. D. Schwarz2, and H. Fuchs1,3 — 1Institute of Physics, University of Münster, Münster, Germany — 2Department of Mechanical Engineering, Yale University, New Haven, CT, USA — 3Center for Nanotechnology (CeNTech), University of Münster, Münster, Germany
The atomic force microscope (AFM) has been established as a tool for the imaging of surfaces with atomic resolution. However, a reliable interpretation of the observed atomic-scale contrast is often difficult. Meaningful comparisons with theoretical simulations would require knowledge of the exact position and identity of all atoms at the tip apex. A determination of the position of the last atoms of the tip is possible using field ion microscopy (FIM). We build an AFM for operation at low temperatures and under ultrahigh vacuum (UHV) conditions using a tuning fork (TF) as force sensor, allowing us to choose an appropriate material such as tungsten as tip material while maintaining atomic-scale resolution capabilities in AFM mode. The combination of an AFM operated in static contact mode with a FIM allows the correlation of interatomic forces with the atomic-scale tip configuration [1]. However, the dynamic mode of operation using the TF technique is expected to greatly enhance the force sensitivity of such measurements. First results obtained with both microscopy methods are presented. Tip radii obtained with the FIM are correlated to the force distance curves measured with the same tips.
[1]G. Cross et al., Phys. Rev. Lett. 80, 4685 (1998)