Dresden 2026 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 29: Emerging Topics in Chemical and Polymer Physics, New Instruments and Methods III

CPP 29.4: Talk

Tuesday, March 10, 2026, 14:45–15:00, ZEU/0255

Solution to the current paradox of anomalous underscreening in electrolytes — •Esther Ohnesorge, Thomas Tilger, Michalis Tsintsaris, Hayden Robertson, and Regine von Klitzing — Department of Physics, Technische Universität Darmstadt, Darmstadt, 64289, Germany

Since colloidal dispersions have a significant importance in our daily life, it is of special interest to get a deeper understanding of which interfacial forces govern their stability and how this stability can be tailored.

For aqueous electrolyte solutions, DLVO theory is a powerful and well-established framework to describe these interactions at low and intermediate ionic strengths. In contrast, the situation at high ionic strength is less understood and the main methods for direct force measurements give inconsistent results. Whilst the surface force apparatus (SFA) provides clear evidence for a re-entrance of repulsion in the highly concentrated regime (termed underscreening) for a wide range of different electrolytes [1], similar observations were not possible with the atomic force microscope (AFM) to date [2]. In this presentation we will examine the reason of these fundamental differences. Specifically, in an attempt to explore experimental screening lengths across a wide suite of electrolyte concentrations, we demonstrate the experimental parameters dominating the occurrence of anomalous underscreening and a comprehensive understanding of this long-debated phenomenon. [1] DOI: 10.1103/PhysRevLett.119.026002 [2] DOI: 10.1016/j.jcis.2022.05.004

Keywords: Colloidal Probe AFM; Surface Forces; DLVO Theory; Electrolytes; Underscreening