A theoretical analysis of frictional and defect characteristics of graphene probed by a capped single-walled carbon nanotube

Using molecular dynamics simulations, we show that a probing tip using a short capped single-walled carbon nanotube is able to capture the frictional characteristics and faithfully resolve the graphene lattice through the measurements of oscillatory lateral force or normal force. By averaging the oscillatory lateral force and normal force along the tip moving path, we extract the friction coefficient. It is found that the friction coefficient decreases with increasing both the initial tip-surface distance and the number of graphene layer. The underlying energy dissipation arises from the periodical acceleration-deceleration of the tip, causing the conversion of kinetic energy into thermal energy. We also study the interaction of the tip with a single-layer graphene containing a vacancy or Stone-Thrower-Wales defect, and reveal that the change in lateral and normal forces can be used to differentiate these defects. The present study demonstrates that a short single-walled capped nanotube can serve as an ideal candidate for high-resolution surface probing. (C) 2011 Elsevier Ltd. All rights reserved.