title: Water and ice in contact with octadecyl-trichlorosilane functionalized surfaces: a high resolution x-ray reflectivity study.
abstract: We present a high energy x-ray reflectivity study of the density profiles of water and ice at hydrophobic and hydrophilic substrates. At the hydrophobic water/octadecyl-trichlorosilane (water-OTS) interface, we find clear evidence for a thin density depletion layer with an integrated density deficit corresponding to approximately 40% of a monolayer of water molecules. We discuss the experimental results in terms of a simple model of hydrophobic/hydrophilic solid-liquid interfaces. Our results also exclude the presence of nanobubbles. A detailed study of possible radiation damage induced by the intense x-ray beam at the dry OTS surface and at the ice-OTS, as well as at water-OTS interfaces, discloses that noticeable damage is only induced at the water-OTS interface, and thus points to the dominant role of highly mobile radicals formed in bulk water close to the interface.
authors.affiliation: Max-Planck-Institut fur Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany. mezger@mf.mpg.de
authors.forename: Markus
authors.initials: M
authors.lastname: Mezger
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schöder
authors.forename: Harald
authors.initials: H
authors.lastname: Reichert
authors.forename: Heiko
authors.initials: H
authors.lastname: Schröder
authors.forename: John
authors.initials: J
authors.lastname: Okasinski
authors.forename: Veijo
authors.initials: V
authors.lastname: Honkimäki
authors.forename: John
authors.initials: J
authors.lastname: Ralston
authors.forename: Jörg
authors.initials: J
authors.lastname: Bilgram
authors.forename: Roland
authors.initials: R
authors.lastname: Roth
authors.forename: Helmut
authors.initials: H
authors.lastname: Dosch