SUBSTRATE-INDUCED INTERACTIONS BETWEEN WATER AND CARBON MONOXIDE ON NI(100) AND CU(100)

The interaction between carbon monoxide and water was studied on two different metal surfaces, Ni(100) and Cu(100), using high resolution electron energy loss spectroscopy (HREELS). In the case of Ni(100) it was found that water could displace CO from on-top sites to both bridge and four-fold sites. The effect is strongest when the CO coverages are low and the water coverages are high. In the limit of very low CO coverages, all the CO can be displaced to four-fold sites, and the C-O stretching frequency falls as low as 1410 cm(-1). In sharp contrast, virtually no change in the C-O stretching frequency is seen for any combination of relative CO and water coverages on Cu(100). These results are compared to other UHV and electrochemical measurements.