Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 87: Solid-liquid interfaces: Structure, spectroscopy
O 87.5: Talk
Thursday, March 12, 2026, 16:00–16:15, TRE/PHYS
How Water Controls Ion Adsorption at Aqueous Interfaces via Entropic and Dielectric Interplay — •Florian Altmann1, Matteo Olgiati1, Moritz Zelenka2, Joanna Dziadkowiec3, Andreas Kretschmer1, Alper T. Celebi1, Laura L.E. Mears1, Ellen H.G. Backus2, and Markus Valtiner1 — 1Vienna University of Technology, Institute of Applied Physics, Wiedner Hauptstrasse 8-10, A-1040, Vienna, Austria — 2University of Vienna, Faculty of Chemistry, Institute of Physical Chemistry, Währinger Straße 42, 1090 Vienna, Austria — 3NJORD Centre, Department of Physics, University of Oslo, Oslo 0371, Norway
Ion-specific behavior at aqueous interfaces remains poorly understood. Using Li+, Ca2+, and Cs+, we combine quantitative atomic force microscopy on muscovite mica with molecular dynamics simulations and sum-frequency generation spectroscopy to resolve interfacial thermodynamics at molecular resolution. Pair correlation functions link ion-water-surface organization to entropy and electrostatics. Small or highly charged ions compact interfacial water, creating entropic penalties and strong dielectric screening, whereas larger ions deplete interfacial water, lower screening, and promote overadsorption. This interplay between entropy and screening governs inner double-layer formation and provides a molecular framework for ion-specific adsorption in complex electrolytes.
Keywords: interfacial thermodynamics; electric double layer structure; molecular dynamics simulations; pair correlation functions