Regensburg 2022 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Interfaces and Thin Films and Responsive and Adaptive Systems

CPP 37.7: Vortrag

Donnerstag, 8. September 2022, 12:30–12:45, H39

The surface of electrolyte solutions is stratified — •Yair Litman, Kuo-Yang Chiang, Takakazu Seki, Yuki Nagata, and Mischa Bonn — MPI for Polymer Research, Mainz, Germany.

The electrical-double layer (EDL) model has been used during the last two decades to describe the behaviour of ions at the water/air interface, and also as a framework to analyze and interpret several types of surface-selective experimental measurements. In this work, we present a combination of surface-sensitive heterodyne-detected vibrational sum frequency generation (VSFG) and ab initio based molecular dynamics simulations to study the liquid/air interface of different aqueous electrolyte solutions. Our VSFG measurements clearly demonstrate that the EDL model is an incomplete microscopic picture to understand the interface of NaCl, NaBr and NaCl aqueous solutions and it is completely inappropriate for the NaOH and CsF cases. Based on our simulations, we propose that the surface of electrolytes solutions is stratified into two water layers, one depleted and the other enriched with ions, creating an effective liquid-liquid interface buried a few Å inside the solution.