Atomic Force Microscopy Study of Forces between a Silica Sphere and an Oxidized Silicon Wafer in Aqueous Solutions of NaCl, KCl, and CsCl at Concentrations up to Saturation

作者：Wang Yuhua; Wang Liguang^*; Hampton Marc A; Nguyen Anh V

来源：Journal of Physical Chemistry C, 2013, 117(5): 2113-2120.

DOI：10.1021/jp3092495

This paper describes the measured forces between a spherical silica particle and a planar oxidized silicon wafer in NaCl, KCl, and CsCl aqueous solutions using an atomic force microscope (AFM). The magnitudes of measured forces are sensitive to electrolyte type and concentration over a broad range of 0.01-4 M under study. Increasing NaCl and KCl concentrations finds the suppression of repulsion at low concentrations, the appearance of attraction at an intermediate concentration, and the suppression of the attraction at high concentrations. In contrast, no attractions were detected for CsCl solutions except at 0.5 M, and increasing the concentration would lead to suppression of repulsion at the low concentration range and enhancement of repulsion at the high concentration range. The deviation between the measured total force and the calculated double-layer repulsion can be represented in the form of a power law incorporating an effective Hamaker constant (A(eff)) and an offset separation distance.

• 出版日期2013-2-7