Regensburg 2016 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 63: Interfaces and Thin Films II (joint session CPP/DY, organized by CPP)

CPP 63.7: Talk

Friday, March 11, 2016, 11:15–11:30, H51

Properties of a monomolecular water film flowing into a graphene-mica slit pore — •André Schilo, Nikolai Severin, Igor M. Sokolov, and Jürgen P. Rabe — Department of Physics, Humboldt-Universität zu Berlin, Germany

Nanoscopically confined water and water adsorbed at interfaces play an important role in e.g. biology, tribology or nanotechnology. Graphene has recently been demonstrated to replicate the substrate topography with a precision down to single macromolecules. Thus the flexible graphene cover provides the possibility of visualizing a water monolayer confined in a slit pore between graphene and mica. However, the phase of the confined water (solid or fluid) is still debated. Here we report high-resolution scanning force microscopy (SFM) imaging of water monolayers flowing into the slit pore. The initially dry pore gets filled upon raising the ambient humidity. We observed a layer of water wetting the sample in reproducible finger-shaped patterns with a step height of 2.8 Å. The flow kinetics are highly dependent on the rate of humidity change. Keeping the humidity constant at a value above the beginning of the wetting process and below the complete wetting, results in a nearly exponential saturation of the finger growth. A further increase of the humidity reactivates the growth of the fingers, eventually leading to a complete monolayer of water. From this we conclude that the confined water monolayer must be fluid.