Surface Water Molecules Govern Corrosion
April 8, 2010
It may seem a harmless question to ask how molecules of water arrange themselves to cover a surface, but the answer has big consequences. For instance, the drag experienced by water flowing past a surface affects the transport of pollutants in the environment. And the initial growth of ice crystals on dust is essential to the formation of raindrops.
In 2001, senior scientist Peter Feibelman at Sandia National Laboratories, Albuquerque, proposed an unexpected solution to a long-standing experimental mystery concerning a one-molecule thick layer of water on ruthenium, a rare polyvalent metallic element of the platinum group, with atomic number 44. By giving up a hydrogen atom, half the layer’s water molecules find themselves more attracted to the surface. They therefore move closer to it, just as was seen, but not understood, in a 1994 diffraction experiment.
Feibelman, who has written a technical paper and has had articles published on the topic in science journals, has reviewed “what is going on,” on this topic.
In the opening paragraph of his review for “Physics Today,” the article says, “The first layer of water molecules at a surface is the structural template that guides the growth of ice, embodies the boundary condition for water transport, and mediates aqueous interfacial chemistry. It thus determines if rain will fall, how fast pollutants migrate in rock and soil, and governs corrosion, catalysis, and countless other processes.”
To read Feibelman’s full article, a subscription is required to “Physics Today.” Interested parties can visit www.physicstoday.org and type in “The First Wetting Layer on a Solid” in the search box, then purchase a copy of the full article for $23.