title: Liquid flow along a solid surface reversibly alters interfacial chemistry.
abstract: In nature, aqueous solutions often move collectively along solid surfaces (for example, raindrops falling on the ground and rivers flowing through riverbeds). However, the influence of such motion on water-surface interfacial chemistry is unclear. In this work, we combine surface-specific sum frequency generation spectroscopy and microfluidics to show that at immersed calcium fluoride and fused silica surfaces, flow leads to a reversible modification of the surface charge and subsequent realignment of the interfacial water molecules. Obtaining equivalent effects under static conditions requires a substantial change in bulk solution pH (up to 2 pH units), demonstrating the coupling between flow and chemistry. These marked flow-induced variations in interfacial chemistry should substantially affect our understanding and modeling of chemical processes at immersed surfaces.
authors.affiliation: Department of Physics, University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium. dan.lis@unamur.be bonn@mpip-mainz.mpg.de.
authors.forename: Dan
authors.initials: D
authors.lastname: Lis
authors.affiliation: Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Ellen H G
authors.initials: EH
authors.lastname: Backus
authors.affiliation: Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Hunger
authors.affiliation: Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Sapun H
authors.initials: SH
authors.lastname: Parekh
authors.affiliation: Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany. dan.lis@unamur.be bonn@mpip-mainz.mpg.de.
authors.forename: Mischa
authors.initials: M
authors.lastname: Bonn