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arXiv · 2308.14571

Interaction of surface cations of cleaved mica with water in vapor and liquid forms

Giada Franceschi·Sebastian Brandstetter·Jan Balajka·Igor Sokolović·Jiri Paveleć·Martin Setvín·Michael Schmid·Ulrike Diebold
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Abstract

Natural minerals contain ions that become hydrated when they come into contact with water in vapor and liquid forms. Muscovite mica -- a common phyllosilicate with perfect cleavage planes -- is an ideal system to investigate the details of ion hydration. The cleaved mica surface is decorated by an array of K$^+$ ions that can be easily exchanged with other ions or protons when immersed in an aqueous solution. Despite the vast interest in the atomic-scale hydration processes of these K$^+$ ions, experimental data under controlled conditions have remained elusive. Here, atomically resolved non-contact atomic force microscopy (nc-AFM) is combined with X-ray photoelectron spectroscopy (XPS) to investigate the cation hydration upon dosing water vapor at 100 K in ultra-high vacuum (UHV). The cleaved surface is further exposed to ultra-clean liquid water at room temperature, which promotes ion mobility and partial ion-to-proton substitution. The results offer the first direct experimental views of the interaction of water with muscovite mica in UHV. The findings are in line with previous theoretical predictions.

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Giada Franceschi, Sebastian Brandstetter, Jan Balajka, Igor Sokolović, Jiri Paveleć, Martin Setvín, Michael Schmid, Ulrike Diebold. 2023-08-28. Interaction of surface cations of cleaved mica with water in vapor and liquid forms. https://doi.org/10.1039/d3fd00093a

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