Abstract:
We have determined the ordering properties of water adsorbed at room
temperature on the rock salt (100) surface under four different conditions:
ultrahigh vacuum, dry nitrogen atmosphere, 45% and 75% relative humidity.
Details of the atomic structure are determined for both sides of the solid-liquid
interface. The top most layer of NaCl shows a small relaxation that changes
from an expansion to a contraction with increasing humidity. Under all
measured conditions water monolayers with different ordering properties
are present at the interface. Surprisingly, we find that the amount of
ordering in the first layer is increasing with increasing thickness of
the water film. At a solid-liquid interface, the ordering appears to be
correlated with the solubility.