Adhesion forces between surface-modified AFM tips and a mica surface

The adhesion force between modified AFM tips and a mica substrate has been studied using an atomic force microscope. The force-distance curves measured by the microscope show that the adhesion force is sensitive to the surface energies of the materials coated on the tips. The adhesion force between a gold-coated tip and a mica surface is much larger than that between a paraffin-coated tip and a mica surface. A simple calculation shows that this behavior of the adhesion forces can be accounted for by the van der Waals and capillary forces between the AFM tips and the substrate.