Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 15: Methods: Scanning Probe Techniques II

O 15.1: Talk

Monday, March 26, 2007, 14:15–14:30, H41

Advances in High Resolution 3-Dimensional Force Field Spectroscopy — •Alexander Schwarz, Uwe Kaiser, and Roland Wiesendanger — Institut für Angewandte Physik, Department Physik, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg

Atomic force microscopy using the frequency modulation technique (FM-AFM) can be employed to image surfaces with atomic resolution. Force spectroscopy allows determining the distance dependence of the tip-sample interaction force. Recently, both methods have been combined by recording spectroscopy curves at every x,y image point. This 3-dimensional force field spectroscopy technique (3D-FFS) [1,2] can be used to evaluate details of the tip-sample interaction with high resolution.

In our presentation, we will discuss the requirements to acquire high-resolution 3D-force-fields together with the dissipation signal due to non-conservative tip-sample interactions. As sample we will show data obtained on NiO(001). At close tip-sample separations, the force field F(x,y,z) and the dissipation E_Diss(x,y,z) is analysed with respect to reconfigurations of atoms at the tip apex. Such reconfigurations influence the atomic scale contrast and are therefore very important to understand the relevant effects and mechanisms during atomic resolution imaging.

[1] H. Hölscher et al. Appl. Phys. Lett. 81, 4428 (2002).

[2] S. M. Langkat et al. Surf. Sci. 521, 12 (2003).