We demonstrate reversible wetting and filling of open single-wall carbon nanotubes with mercury by means of electrocapillary pressure originating from the application of a potential across an individual nanotube in contact with a mercury drop. Wetting improves the conductance in both metallic and semiconducting nanotube probes by decreasing contact resistance and forming a mercury nanowire inside the nanotube. Molecular dynamics simulations corroborate the electrocapillarity-driven filling process and provide estimates for the imbibition speed and electrocapillary pressure.

Imaging of surfaces with carbon nanotube probes in tapping mode results frequently in complex behavior in the amplitude-distance curves monitored. Using molecular mechanics simulations, we calculate the force exerted on a nanotube pressed against a smooth surface as it undergoes deformation and buckling. This nonlinear force is then used in a macroscopic equation, describing the response of a damped harmonic oscillator, to predict the amplitude response of a nanotube AFM probe. Similarities between the prediction and experiment suggest that the complex amplitude response seen in the experiment may be explained by the nonlinearity in the force exerted on the nanotube and thus must not necessarily be related to the structure of the surface.