HREELS, LEED and angle-scanned XPD investigation of the coadsorption of CO and NO on Ni(111)

The coadsorption of CO and NO on Ni(lll) at room temperature has been studied by HREELS, LEED and angle-scanned XPD techniques. The experiments have been carried out by first exposing the clean surface to one gas up to the observation of a c(4 x 2) LEED pattern, and then by monitoring the step-wise addition of the other. CO does not modify or adsorb on a c(4 x 2)-NO layer, while 1 L NO causes the complete desorption of a c(4 x 2)-CO layer. The LEED pattern is always c(4 x 2), even if both CO and NO species are present on the surface. For NO exposures lower than 1 L of the GO-covered Ni(lll) surface, XPD measurements show that NO molecules are in a bent geometry, while CO molecules are perpendicular to the surface. Our results indicate that the NO-Ni interaction is very weakly affected by the presence of coadsorbed CO.