Department of Inorganic, Analytical, and Applied Chemistry, University of Geneva, 30, Quai Ernest-Ansermet, 1205 Geneva, Switzerland.
Phys Rev Lett. 2010 Jun 4;104(22):228301. doi: 10.1103/PhysRevLett.104.228301. Epub 2010 Jun 2.
Direct force measurements between oppositely charged latex particles in aqueous electrolyte solutions were carried out with a multiparticle colloidal probe technique based on atomic force microscopy. Force profiles between two dissimilarly charged surfaces can be only described when charge regulation effects are taken into account, while constant charge or constant potential boundary conditions are inappropriate. Surface potentials and regulation parameters are determined from force data obtained in symmetric systems with the Poisson-Boltzmann theory and constant regulation approximation. The resulting quantities are used to predict the force profiles in asymmetric systems, and good agreement between theory and experiment is found. These findings show that charge regulation is important to quantify double-layer forces in asymmetric systems.
采用基于原子力显微镜的多颗粒胶体探针技术，在水溶液电解质中测量了带相反电荷的乳胶颗粒之间的直接力。只有考虑电荷调节效应时，才能描述两个带不同电荷表面之间的力曲线，而恒电荷或恒电位边界条件是不适当的。表面电势和调节参数是根据泊松-玻尔兹曼理论和恒调节近似从对称系统中获得的力数据确定的。所得量用于预测非对称系统中的力曲线，并且在理论和实验之间发现了很好的一致性。这些发现表明，电荷调节对于量化非对称系统中的双层力很重要。
