Probing the interface potential in stick/slip friction by a lateral force modulation technique

The influence of the shape of the interaction potential is investigated on details in stick/slip friction as encountered between an AFM tip and a substrate. Based on qualitative arguments of stick/slip systems, a novel technique is introduced in which the AFM tip is brought into a lateral resonance mode. In comparison to a direct measurement in the stick/slip signal, we suggest that the method is preferable to highlight these non-linear characteristics. In combination with the shape of the surface potential involved in stick/slip friction, this modulation diminishes the friction loop amplitude in a controlled way. Furthermore, a partial stick/slip behavior is observed above a certain threshold level of driving amplitude, where the tip alternates periodically between a zero-friction and a non-zero-friction state. (C) 1998 Elsevier Science B.V. All rights reserved.