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CPP: Chemische Physik und Polymerphysik
CPP 27: POSTER Polymer Physics and Materials
CPP 27.26: Poster
Donnerstag, 30. März 2006, 17:00–19:00, P2
Effect of high-frequency oscillatory shear on the force of detachment of an AFM tip from a solid surface — •Binyang Du1, Sergiy Rudenkiy1, Pattrawin Gasemjit1, Lars-Oliver Heim2, and Diethelm Johannsmann1 — 1Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, 38678, Clausthal-Zellerfeld — 2Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz
The force of detachment between an AFM-tip and a material surface, namely the pull-off-force, is a key parameter for characterization of adhesive interactions on the nanometer scale. Experiments have shown that the pull-off-force can depend on the loading rate, at which the force is ramped up. Kramer’s theory also predicts a logarithmic dependence on the loading rate, which has indeed been found in various experiments. Here we report on the pull-off-force between an AFM tip and a quartz crystal under high-frequency oscillatory lateral shear as a function of shear amplitude. The pull-off-force (more precisely: the pull-off-distance) was determined repeatedly and automatically at a rate of 0.5 Hz, while the quartz crystal was swept through a resonance. The shear amplitude is typical in a range of nanometer. The pull-off-distance decreases with increasing the shear amplitude. By plotting the pull-off-distance versus the logarithm of shear amplitude, one finds a linear dependence over a range of more than a decade. This behavior can be rationalized by assuming a multicontact interface with an exponential distribution of peak heights.