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O: Fachverband Oberflächenphysik

O 44: Focus Session: Structure, Chemistry, and Ion Solvation at Solid-Liquid Interfaces III

O 44.1: Talk

Wednesday, March 18, 2015, 10:30–10:45, HE 101

AFM investigation of charge distribution and ion adsorption at solid-liquid interfaces — •Frieder Mugele¹, Igor Siretanu¹, Cunlu Zhan¹, Dirk van den Ende¹, and Daniel Ebeling^1,2 — ¹University of Twente, MESA institute for Nanotechnology; Physics of Complex Fluids, Enschede, The Netherlands — ²Universität Giessen, Giessen, Germany

Solid surfaces immersed in water almost invariably assume a finite surface charge typically due to either (de)protonation of functional groups on the surface or adsorption of ions from the solution. While the resulting electrostatic interaction forces are crucial for many phenomena in science and technology, such as colloid science, biophysics, foodtechnology, and enhanced oil recovery, important aspects of charge distribution and spatial arrangement of adsorbed ions in the Stern layer are poorly understood. Here, high resolution dynamic atomic force spectroscopy and microscopy experiments in ambient liquid will be described that provide detailed insight into the organization of ions in the Stern layer at various mineral-electrolyte interfaces. The experiments highlight the preferential adsorption of divalent cations (Mg2+, Ca2+) as compared to monovalent ones (Na+, K+), including the incorporation of Cl- co-ions at higher concentrations. Complementary Density Functional Theory calculations demonstrate the role of hydration water upon adsorption.