Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 34: Rastersondentechniken II

O 34.3: Talk

Monday, March 7, 2005, 11:15–11:30, TU EB407

Adhesion force measurements for well-defined probe - sample geometries — •Bert Stegemann, Henrik Backhaus, Heinz Kloß, and Erich Santner — Bundesanstalt für Materialforschung, BAM - VIII.1 Tribologie und Verschleißschutz, Unter den Eichen 44-46, D-12205 Berlin

Adhesion is of fundamental importance for the tribological behavior, e.g., in nanomechanical devices. A promising approach to determine interfacial adhesion at sub-micron scale is to measure pull-off forces with an atomic force microscope (AFM). As adhesion depends on numerous factors, such as contact area, environment and dynamics, there is still a lack of reliable quantitative data. Here, we report on a systematic analysis of AFM pull-off forces for well-defined systems under ultrahigh vacuum conditions. Interaction geometry is controlled by means of colloid AFM probes, i.e., microspheres attached at the end of bare AFM cantilevers. Clean sample surfaces of a wide range of single crystal metals and compound materials were prepared by subsequent Ar ion sputtering and annealing as affirmed by surface analytical techniques. The influence of experimental parameters, like applied load, contact time and contact area on the pull-off forces is discussed. The results obtained are compared with predictions from theoretical models and correlated with macroscopic mechanical properties of the materials.