CPM Seminar

To slide or not to slide: Frictional duality of nanoparticles

Andre Schirmeisen

Center for Nanotechnology (CeNTech)
Universität Münster

It's no surprise that a block sliding across a table is slowed by friction, but for small enough crystals, theory and a few experiments suggested that frictionless motion may be the norm. We investigate nanoscale friction by pushing Antimony nanoparticles over a graphite surface using atomic force microscopy techniques in ultrahigh vacuum [1]. This technique allows us to quantify static as well as sliding friction for extended nanocontacts [2]. In particular the sliding friction during particle pushing shows two distinct states: Either the friction scales linear with the island-substrate contact area or it is hardly detectable at all [3]. This frictional duality can be understood if partial contamination of the interface by mobile surface molecule is assumed. New experiments with improved sensitivity shed light on the zero friction state: Here the pushing resistance scales roughly with the square root of the contact area, a dependence predicted by current theories of superlubricity.

[1] Schirmeisen and Schwarz, Chem PhysChem 10, 2373 (2009)
[2] D. Dietzel et al., Appl. Phys. Lett. 95, 053104 (2009)
[3] D. Dietzel et al., Phys. Rev. Lett. 101, 125505 (2008)