Effect of sliding velocity on capillary condensation and friction force in a nanoscopic contact

The influence of sliding velocity on the friction force in a nanoscopic contact was studied on a hydrophilic silicon nitride surface with an Atomic Force Microscope. By submitting a nanoscopic contact to small oscillating lateral displacements, we observe both decreases of the friction force and of the contact radius with an increase of the sliding velocity. We found experimentally that this decrease of the friction force and of the contact radius is correlated to a decrease of the capillary force.