EFFECT OF TIP SHAPE ON FORCE DISTANCE CURVES FOR AFM IN AQUEOUS-ELECTROLYTES

In this study, we calculated the force-distance curves consisting of the van der Waals force and the electric double layer force in an electrolyte in the AFM with a realistic shape tip without the approximation of a low electrostatic potential. The calculation was compared with the experimentally obtained data. A complete sphere model can be applicable when 2θ ≦ 30°, but the Derjaguin approximation is not suitable for R ≦ D. A rigorous calculation without the approximation of a low potential can lead to better fitting with the experimental data, and thus the pH dependence curve of γ1γ2, which gives us the isoelectric point. © 1994.