Nanoscopic friction under electrochemical control
Astrid de Wijn
University of Stockholm, Sweden
A unique path to control and ultimately manipulate forces between material surfaces is through an applied electric field. Several experimental and theoretical studies of electro chemical interfaces demonstrated that the orientation of polar molecules adsorbed at electrode surfaces is potential dependent. We propose a theoretical model for friction under electrochemical conditions focusing on the interaction of a force microscope tip with adsorbed polar molecules of which the orientation depends on the applied electric field. The dependence of friction force on the electric field is shown to be determined by the interplay of two channels of energy dissipation: (i) the rotation of dipoles and (ii) slips of the tip over potential barriers. We use this model to investigate the effects of molecule anchoring to the surface, and the dispersion in the layer of molecules. The effects of oscillating fields are investigated as well.
[1] Nanoscopic friction under electrochemical control A. S. de Wijn, A. Fasolino, A. Filippov, M. Urbakh, Phys. Rev. Lett. 112, 055502 (2014).
[2] Effects of molecule anchoring and dispersion on nanoscopic friction under electrochemical control A. S. de Wijn, A. Fasolino, A. E. Filippov, and M. Urbakh, J. Phys.: Condens. Matter 28, 105001 (2016).