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O: Fachverband Oberflächenphysik

O 58: Mini-Symposium: Molecular scale investigations of liquid-vapor interfaces II

O 58.3: Hauptvortrag

Mittwoch, 3. März 2021, 11:20–11:50, R1

Surface activity of hydroxide and the hydrated proton — •Ellen Backus — Institut für Physikalische Chemie, Wien, Österreich — Max-Planck-Institute für Polymerforschung, Mainz, Deutschland

The behavior of hydroxide and hydrated protons, the auto-ionization products of water, at surfaces is important for a wide range of applications and disciplines. Despite of its importance, the likelihood of surface adsorption of either of those two ions is controversially discussed in literature. By determining the onset concentration of surface adsorption at the water-air surface of hydrated protons and hydroxide ions, we can determine the relative surface-activity. To this order, we perform surface-sensitive vibrational sum frequency generation spectroscopy - basically providing the vibrational spectrum of just the interfacial layer - on the O-H stretch vibration. We will discuss how spectral changes in the response from hydrogen bonded molecules can be related to the surface adsorption of the hydrated ions. Moreover, changes in the spectral signature of the so-called free OH molecule sticking out in the air are used to determine the adsorption free energy of the proton.