Vibrational spectroscopic investigation of NO and CO co-adsorption on Pt{100}

The coadsorption of NO and CO on Pt{100} at 300 K has been investigated using infrared reflection-absorption spectroscopy (IRAS). At low coverages, regardless of the order of adsorption, mixed NO/CO islands are formed on (1 × 1) domains. This causes the stretching modes of both species to shift down in frequency due to reduced dipole-dipole coupling. The lowest frequency of approximately 2050 cm-1 observed for CO fully diluted in NO is only approximately 10 cm-1 less than 12C16O diluted in 12C18O, indicating a relatively small chemical interaction. NO/CO mixing is not observed on the (hex) surface at 300 K, since NO immediately lifts the reconstruction. In all cases, CO was able to penetrate an NO layer and eventually remove it, but a saturated CO layer cannot be penetrated by NO.