Analysis on Electrostatic Tip-Sample Interaction in Aqueous Solution under Potentiostatic Condition

Using a force microscopy, we investigated electrostatic tip-sample interaction in aqueous solutions. A force between a gold-coated microsphere tip and an oxidized silicon sample was measured with their surface potentials being controlled independently by bipotentiostat. The variations in the force characteristics were observed with the respective changes in the tip potential and the sample potential. The observed force characteristics were found to agree with the theory of electrical double layer interaction under constant potential assumption.