THE EFFECT OF ATOMIC-SCALE SURFACE DISORDER ON BONDING AND ACTIVATIONOF ADSORBATES - VIBRATIONAL PROPERTIES OF CO AND CO2 ON COPPER

Important details are resolved in the SERS spectra of CO and CO2 on di sordered copper surfaces at 40 K. The spectrum of chemisorbed CO featu res four vibrational modes: a CO stretch vibration, a frustrated rotat ion and two frustrated translations, perpendicular and parallel to the local surface. The bands originate from a CO species singly coordinat ed to electron deficient defect sites, with the bond strength increase d compared to non-defect adsorption. In the case of adsorbed CO2 two d istinct adsorption states due to an activated and a non-activated surf ace species are observed. The activation is promoted by low temperatur e stabilized surface defects and is prohibited on an annealed copper s urface.