Determination of electrostatic potential distribution by atomic force microscopy (AFM) on model silica and alumina surfaces in aqueous electrolyte solutions

摘要

AFM was employed as a physicochemical probe to determine the electrostatic potential distribution quantitatively on selected ideal oxide surfaces (quartz 0001 and sapphire 0001) in aqueous media. The force of interaction between a silicon nitride tip and the oxide surface was measured at a given point under well-defined solution conditions. Relevant theories were used to isolate the electrostatic component from the total force of interaction which was then employed to estimate the surface potential at that point. Repeating the procedure on selected locations generated a potential map of the surface. Comparison of these potentials with those obtained from independent electrokinetic measurements confirmed the validity of the approach.