Characterization of nanoscale adhesion between a fluoroalkyl silane monolayer and a silicon AFM tip. Complex character of the interaction potential

Using a modified atomic force microscope, the nanoadhesion between a silicon tip and a monolayer of 1H, 1H, 2H, 2H-perfluorodecyl trichlorosilane was measured at different loading rates. The adhesion force versus loading rate curve could be fitted with two logarithmic terms. The application of a model of thermally activated escape from a bound state to the analysis of the curves made it possible to extract quantitative information about the effective adhesion potential. Although only van der Waals interactions appear to make a major contribution to the nanoadhesion, the interaction potential characterizing the nanoadhesion still has a complex, two-transition state character.