Novel tip modification method for measurement of the adhesive force between a silanized surface and a locally modified tip using atomic force microscopy

Chemical force microscopy using probe tips subjected to liquid-phase chemical modification enables the study of intermolecular forces on a nanoscale, as well as imaging of the chemical inhomogeneity of a sample's surface with high spatial resolution. However, in adhesive force measurements, the adhesive force between the tip and the sample could easily be affected by interactions caused by molecules in both the contact and the noncontact parts. A novel method involving local chemical modification of the tip is presented. The method is performed by adding a solution of a modification reagent in ethanol when the cleaned tip is approaching the substrate's surface. The adhesive forces between the substrate's surface and various types of tips were investigated using atomic force microscopy. This novel method could be helpful for increasing the resolution of chemical force microscopy and for measuring the contact area between the tip and the substrate's surface.