Water and ice in contact with octadecyl-trichlorosilane functionalized surfaces: a high resolution x-ray reflectivity study.
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.
Mezger
Markus
M
Max-Planck-Institut fur Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany. mezger@mf.mpg.de
Schöder
Sebastian
S
Reichert
Harald
H
Schröder
Heiko
H
Okasinski
John
J
Honkimäki
Veijo
V
Ralston
John
J
Bilgram
Jörg
J
Roth
Roland
R
Dosch
Helmut
H