Coadsorption of water and CO molecules on Ru(001) at high CO coverages: comparisons with a Ru(001) electrode surface

The coadsorption of carbon monoxide (CO) and water molecules on a Ru(0 0 1) surface has been studied by infrared spectroscopy, LEED and STM. At high CO coverage phases, a 2 x 2-(2CO + D2O) structure was observed on both UHV and electrode surfaces. Electrode potential dependent structures from CO and water adlayers on an electrode surface were reproduced on a UHV surface by controlling molecular orientations of the first layer and second overlayer water molecules. At lower CO coverages, a CO band center showed coverage dependent shift down to 1444 cm(-1) due to an electron transfer from a lone pair of a water molecule to CO 2 pi (*). (C) 2001 Elsevier Science B.V. All rights reserved.