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Zusammenfassung:
The coadsorption and reaction of CO2 with a layer of molecular oxygen preadsorbed on a Ag(110) surface have been studied with high resolution electron energy loss spectroscopy (HREELS). Clear evidence has been found for a direct reaction of CO2 and O2 to CO3 at 100 K, resulting in a product coverage higher than attainable with atomic oxygen in the (2×1)O reconstruction. All internal modes of CO3 have been detected, including the in-plane bend and the asymmetric stretch modes, which are degenerate at intermediate but split at saturation coverages. An intermediate species has been observed to be stable only in coadsorption with molecular oxygen, and has been tentatively assigned to a CO-4 anion. The quantitative analysis of the isotopic shift observed with 13C16O2, 12C18O2 and 18O2 is consistent with a planar adsorption geometry of a structurally unmodified CO3 anion bound via the central carbon atom.
