CHARGE DYNAMICS AND TIME EVOLUTION OF CONTACT POTENTIAL STUDIED BY ATOMIC FORCE MICROSCOPY

We experimentally exhibit a time evolution of the contact potential measured between an atomic force microscopy (AFM) tip and a metallic surface. To understand this effect, we propose a simple model involving migration of charged contaminants located on the surface. These results show that AFM used in the resonant mode can be used to study diffusion and surface transport phenomena.