SKM 2023 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Solid-Liquid Interfaces I: Structure and Spectroscopy

O 60.1: Talk

Wednesday, March 29, 2023, 15:00–15:15, TRE Phy

Investigation of the water structure at the (001) and (010) orthoclase surfaces with three-dimensional atomic force microscopy — •Franziska Sabath, Ralf Bechstein, and Angelika Kühnle — Physical Chemistry I, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld

Feldspars are the most abundant minerals in the Earth's crust and belong to the most effective group of mineral ice nucleating particles (INP) in the atmosphere. In the crystal structure, potassium, sodium or calcium, among others, are incorporated as counterions in varying ratios. Potassium-rich feldspars are more effective INPs than the other feldspars. A representative of a potassium-rich feldspar is orthoclase. Unlike other INPs, such as silver iodide, the surfaces of feldspar do not have an ice-like structure. Therefore, it is interesting to know what other factors, such as hydroxyl groups on the surfaces or defect sites, are responsible for the high ice nucleating efficiency of K-feldspars. In particular, the water structure at the interface of K-feldspars is of interest. Here, we show the three-dimensional water structure at the two natural cleavage planes of orthoclase, the (001) and the (010) surfaces, using tree-dimensional atomic force microscopy (AFM).