The oxidation silver and rhodium surfaces are compared.  In particular, I will discuss how the structures formed at high oxygen coverages differ for the metals and how their chemistries may be affected.<br/> <br/>The interaction of oxygen with the surfaces of catalytically active transition metals has attracted much interest because of the relevance to heterogeneous catalysis. Recently, we have shown that oxygen coverages in excess of 1 ML are achievable using gas-phase atomic oxygen (AO) to dose the metal surfaces. This talk will discuss some recent results comparing the uptake of AO and O2 on Ag(111), Rh(111), and curved Ag(111). On c-Ag(111) surfaces, the geometry of the monoatomic steps determines whether or not O will accumulate and the consequent surface reconstruction. Conversely, on Rh(111), subsurface oxygen readily forms from exposure to AO. Finally, the uptake of oxygen on Ag(111) is discussed; unlike Rh(111), where little surface reconstruction occurs, Ag(111) undergoes several phase transformations as the oxygen coverage is increased. These results using AO demonstrate that UHV compatible dosing can prepare the same surfaces resulting high pressure O2 exposures, allowing for quantitative and structural analysis of the oxidized surfaces.

Chemical speciation and structural evolution of rhodium and silver surfaces with high oxygen coverages

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