Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 87: Solid-liquid interfaces: Structure, spectroscopy
O 87.4: Talk
Thursday, March 12, 2026, 15:45–16:00, TRE/PHYS
Structural Stability of NaCl and KCl Cleavage Surfaces in the BMIM-PF6 Ionic Liquid — •Ebru Cihan1, Natalia Janiszewska2, Kamil Awsiuk2, Qingwei Gao3, Rong An4, Ronen Berkovich5, and Enrico Gnecco2 — 1TU Dresden, Dresden, Germany — 2Jagiellonian University, Krakow, Poland — 3Shanghai University of Electric Power, Shanghai, China — 4Nanjing University of Science and Technology, Nanjing, China — 5Ben-Gurion University of the Negev, Beer-Sheva, Israel
An investigation was conducted into the evolution of freshly cleaved NaCl(100) and KCl(100) surfaces exposed to the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). The surfaces were repeatedly scraped using AFM, resulting in contrasting responses from the two surfaces to the IL. In the case of NaCl, the cleavage step edges are slightly eroded, and the surface is progressively smoothed by the AFM tip. These changes are accompanied by a continuous increase in the friction force. In the case of KCl, a pronounced dissolution of the surface is evident immediately following contact with the IL. The surface is then smeared in the area scratched by the tip and even beyond. An increase in the friction force is also observed but only at the onset of the surface modification process. Crystallites (100-200 nm in size) are observed across the unscratched areas of KCl, but not of NaCl. This result was corroborated by MD simulations and Raman spectroscopy, which revealed that IL exhibits a stronger interaction with the KCl surface, ultimately forming a BMIM-PF6 adlayer. [1] E. Cihan et al., Langmuir 41, 13793 (2025)
Keywords: Atomic force microscopy; Crystals; Ionic liquid; Friction; Layer