Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: Surfaces and Films: Forces, Structure and Manipulation
O 36.6: Vortrag
Dienstag, 26. Februar 2008, 15:30–15:45, MA 041
3D force field measurements using non-contact atomic force microscopy on KBr: Theory and Experiment — •Kai Ruschmeier1,2, Regina Hoffmann3, and André Schirmeisen1,2 — 1Physikalisches Institut, Westfälische Wilhelms-Universität, Wilhelm-Klemm Str. 10, 48149 Münster — 2CeNTech, Center for Nanotechnology, Heisenbergstr. 11, 48149 Münster — 3Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe
Atomic force microscopy is capable of characterizing surfaces with atomic resolution. Here, we use an ultrahigh vacuum atomic force microscope in non-contact mode to measure the three-dimensional force field [1,2] of a KBr(001) surface at room temperature. On a predefined grid we measure the force distance curves over a wide range of tip-sample distances, from attractive to repulsive forces. Atomic resolution surface scans before and after the 3D force curve measurements showing single atomic defects assured an unmodified atomically sharp tip. The subtraction of long-range van-der-Waals and electrostatic forces allows us to extract the short-range chemical forces. The results show good agreement with site-specific atomistic simulations of short-range tip-sample forces for a K+-terminated tip [3] and thus allow us to identify the tip apex atom polarity as well as the lattice sites in our AFM images. Furthermore we calculate the lateral tip sample force from the potential energy landscape and compare these results with theoretical predictions.
[1] H. Hölscher et al., APL 81, 4428 (2002) [2] A. Schirmeisen et al., PRL 97, 136101 (2006) [3] R. Hoffmann et al., PRL 92, 146103 (2004)