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Abstract:
We study the adsorption and reaction of CO2 as a function of temperature between 100 and 700 K in the presence of Na on a Pd(111) surface using high resolution electron energy loss spectroscopy. While CO2 does not react with a clean Pd(111) surface, we find various reaction channels on the Na precovered Pd(111) surface depending on the Na coverage. At intermediate coverage a bent CO28− species with characteristic vibrational bands can be unambiguously identified. This species is stable up to 200 K, and dissociates into CO and oxygen similar to its behaviour on other surfaces, and as reported in a previous photoemission study [Wambach et al., Surface Sci. 209 (1989) 159]. In case the surface has been oxygen contaminated before Na and CO2 exposure surface carbonates can be observed.