The effect of a water overlayer on the chlorine-chemisorbed Ag(100) surface studied by Cl K-edge X-ray absorption fine structure

The effect of a water overlayer on the chlorine-chemisorbed silver(100) surface has been studied by Cl K-edge X-ray absorption fine structure spectroscopy. It is found that chlorine atoms adsorbed on Ag(100) form a simple c(2×2) overlayer with a ClAg bond distance of 2.64±0.03 Å and ClCl distance of 4.06±0.05 Å. By dosing water on the chemisorbed surface, the ClAg bond is elongated to 2.70±0.03 Å and the ClCl bond is shortened to 3.90±0.05 Å. Such a structural change is explained by the partial formation of silver chloride on the surface.