Coadsorption of water monomers with CO on Ru(0 0 1) and charge transfer during hydration processes

Four hydration water molecules were observed on a Ru(0 0 1) surface by infrared reflection absorption spectroscopy (IRAS). An abnormally low frequency shift from 2145 to 1356 cm−1 of a CO molecule adsorbed onto a Ru(0 0 1) surface was observed after coadsorption of water molecules with CO. A flat and a tilted monomer were found to exist as a singleton species at a low and a high coverages, respectively. The degree of charge transfer from an oxygen lone pair of the monomers to a Ru(0 0 1) surface is comparable with that from an alkaline atom on the same surface.