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NEXAFS and FT-RAIRS have been used to investigate the adsorption of CO and CO, on ZnO(OOOT)-O and its modification by copper overlayers. NEXAFS data indicate a C03,-species with the molecular plane within 30" of the surface normal following CO and CO, adsorption on the clean surface at 130 K. Upon low-temperature deposition of a submonolayer Cu film, CO,, -species were no longer formed following CO adsorption, although molecular CO was evidenced with the molecular axis within 20" of the surface normal. A single v(C0) band observed in FT-RAIRS indicates that the C O is adsorbed on 2D Cu(ll0)-like sites in an atop position. Preannealing the Cu film to 400 K led to a redistribution of Cu into 3D islands, as evidenced by FT-RAIRS. Exposure to CO of such a surface at 130 K resulted in both CO and C03,-formation. This suggests thst Cu initially nucleates at the active sites for C03,-formation on Zn0(0001)-0 which are uncovered during the onset of 3D island growth.

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