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O: Fachverband Oberflächenphysik

O 19: Vacuum Science & Technology: Theory and Applications – Poster

O 19.1: Poster

Montag, 9. März 2026, 18:00–20:00, P2

Contact-Separation phenomenon at the Silica-Gold interface: AFM and ToF-SIMS insights — •Nisha Ranjan, Tolga Acartürk, Kathrin Küster, and Ulrich Starke — Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany

Contact-Separation (CS) electrification at solid interfaces constitutes a fundamental phenomenon. However, it often exhibits uncertainties and irreproducibility [1,2]. The silica-gold contact pair is a model example of a dielectric-metal system with a similar elastic modulus that shows a significant variation in charging properties such as polarity reversal among CS surfaces [3]. We aim to understand the phenomenon with interfacial interactions and chemical composition using direct microscale measurements under ultra-high vacuum conditions at the silica-gold interface. We use Atomic Force Microscope/Force Spectroscopy (AFM/FS) to quantify interfacial interactions, such as electrostatic force, van der Waals interaction, contact area, contact pressure, and deformation. Repeated approach-retraction cycles enabled the correlation of mechanical response with charge accumulation and compositional change. We use Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) for surface composition mapping to assess mechanochemistry. Our finding demonstrates that the magnitude of the force is significantly influenced by the charge accumulation. Concurrently, a change in surface composition was also observed. [1] I. Jimidar and J. Méndez Harper, Physics Today 78(8), 54 (2025). [2] D.J. Lacks, Angew. Chem. Int. Ed. 51, 6822 (2012). [3] G. Fatti et al., PRL 131, 166201 (2023).

Keywords: Contact electrification