title: Communication: Slow proton-charge diffusion in nanoconfined water.
abstract: We investigate proton-charge mobility in nanoscopic water droplets with tuneable size. We find that the diffusion of confined proton charges causes a dielectric relaxation process with a maximum-loss frequency determined by the diffusion constant. In volumes less than ∼5 nm in diameter, proton-charge diffusion slows down significantly with decreasing size: for diameters <1 nm, the diffusion constant is about 100 times smaller than in bulk water. The low mobility probably results from the more rigid hydrogen-bond network of nanoconfined water, since proton-charge mobility in water relies on collective hydrogen-bond rearrangements.
authors.affiliation: Van 't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Tibert H
authors.initials: TH
authors.lastname: van der Loop
authors.affiliation: FOM Institute for Atomic and Molecular Physics, Science Park 104, 1098 XG Amsterdam, The Netherlands.
authors.forename: Niklas
authors.initials: N
authors.lastname: Ottosson
authors.affiliation: Institut für Textiltechnik, RWTH Aachen University, Otto-Blumenthal-Strasse 1, 52074 Aachen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Vad
authors.affiliation: Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
authors.forename: Wiebke F C
authors.initials: WF
authors.lastname: Sager
authors.affiliation: FOM Institute for Atomic and Molecular Physics, Science Park 104, 1098 XG Amsterdam, The Netherlands.
authors.forename: Huib J
authors.initials: HJ
authors.lastname: Bakker
authors.affiliation: Van 't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Sander
authors.initials: S
authors.lastname: Woutersen