Modeling the Metal-Solution Interface under Ultrahigh Vacuum: Vibrational Studies of the Coadsorption of Water and Carbon Monoxide on Rh(100)

The coadsorption of D2O and CO on Rh(100) under ultrahigh vacuum has been investigated by using infrared reflection absorption spectroscopy. The results show that the presence of D2O induces partial displacement of the CO molecules from linear to bridged configurations. The resulting spectra are very similar to those observed at equivalent CO coverages in an electrochemical environment. The spectral data indicate that the coadsorption of DzO and CO results in the formation of CO islands of varying coverage and the aggregation of both CO and D20 islands on Rh(100) at temperatures below D2O desorption.