Hydration Structure at the Calcite–Water (10.4) Interface in the Presence of Rubidium Chloride

Solid-liquid interfaces are of significant importance in a multitude of geochemical and technological fields. More specifically, the solvation structure plays a decisive role in the properties of the interfaces. Atomic force microscopy (AFM) has been used to resolve the interfacial hydration structure in the presence and absence of ions. Despite many studies investigating the calcite-water interface, the impact of ions on the hydration structure at this interface has rarely been studied. Here, we investigate the calcite-water interface at various concentrations (ranging from 0 to 5 M) of rubidium chloride (RbCl) using three-dimensional atomic force microscopy (3D AFM). We present molecularly resolved images of the hydration structure at the interface. Interestingly, the characteristic pattern of the hydration structure appears similar regardless of the RbCl concentration. The presence of the ions is detected in an indirect manner by more frequent contrast changes and slice displacements.