We propose a new motion of the ion near the surface of a solid due to the surface potential of the dynamical polarization of the valence-electron cloud induced by the moving ion itself. Under some appropriate conditions the outgoing ions are forced to be drawn once again to the surface by this potential and go through with skipping motions. Computer simulation shows that a large number of ions are trapped in the skipping motions.

• Received 15 January 1979

DOI:https://doi.org/10.1103/PhysRevB.20.5044