Structural Determination of Molecular Overlayer Systems with Normal Photoelectron Diffraction:c(2×2)CO-Ni(001) and(3×3)R30°CO-Ni(111)

Experimental and theoretical normal photoelectron diffraction studies of CO adsorbed on Ni are presented. It is shown for the first time that normal photoelectron diffraction can yield definitive structure determinations in molecular adsorbate systems. The linear-bonded atop geometry of $c(2\mathrm{}\times 2)$ CO- Ni(001) is confirmed, while CO is found to occupy the twofold bridge site in $(\sqrt{3}\times \sqrt{3})R30°$ CO- Ni(111).