Chemical properties of Zn on Ru(001): Coadsorption with Cs, O, Cu, and Au

The coadsorption of Zn with Cs (an electropositive species) or O (an electronegative species) on Ru(001) does not induce significant changes in the thermal stability of the Ru–Zn bond. On the other hand, two‐dimensional CuZn (or AuZn) alloys in contact with Ru(001) show Ru–Zn and Zn–noble metal bonds more stable than the corresponding bonds in Zn/Ru(001) and thick CuZn (or AuZn) alloys. This phenomenon is caused by synergistic interactions in three‐center metal–metal bonding. Photoemission studies indicate that at submonolayer coverages of Zn and O there is no lateral bonding between these species on Ru(001). The formation of ZnO_x films on Ru(001) occurs when the Zn and O coverages are higher than 1 ML. On Zn films supported on Ru(001), the initial adsorption probability of O₂ is extremely low, and O₂ exposures in the range of 10³–10⁴ L are necessary to produce a significant transformation of metallic Zn into ZnO. The presence of Cs enhances the oxidation rate of Zn by 2–3 orders of magnitude. In the Cs/Zn/Ru(001) systems, the alkali adatoms adsorb and dissociate O₂ molecules, producing a reservoir of oxygen species that react with Zn.