We studied the adsorption of water on the O(2x1) -Ru(0001) surface at submonolayer coverage by low temperature scanning tunneling microscopy. We found that water reconstructs the oxygen layer from a linear configuration to a honeycomb structure with the water molecules incorporated inside, confirming a model previously proposed by Gladys et al. based on XPS measurements [1]. In addition, we found that water monomers inside the oxygen hexagons can rotate through interaction with the tip, while dimers are more stable.

 

[1] M.J. Gladys et al. PRB 78, 035409 (2008).