Frictional forces in an electrolytic environment

We propose a theoretical description of frictional phenomena in nanoscale l ayers of electrolyte solutions embedded between two plates, one of which is externally driven. It is shown that the presence of nonuniform charge dist ributions on the plates leads to a space-dependent frictional force, which enters into the equation of motion for the top driven plate. The equation d isplays a rich spectrum of dynamical behaviors: periodic stick-slip, errati c, and intermittent motions, characterized by force fluctuations, and slidi ng above the critical velocity. Boundary lines separating different regimes of motion in a dynamical phase diagram are determined. The dependences of the frictional force and regimes of motion on an electrolyte concentration, a surface charge distribution, and a thickness of the liquid layer are pre dicted. The relevance to existing systems and predictions amenable to diffe rent experiments are discussed.