THE REACTIVE CHEMISORPTION OF CARBON DIOXIDE AT MAGNESIUM AND COPPER SURFACES AT LOW TEMPERATURE

X-ray photoelectron spectroscopic studies reveal that the following species are present when carbon dioxides reactively chemisorbed at magnesium and copper surfaces: CO2(phys) CO3(a), CO2- (a) CO(a) and C(a). At Mg(0001) surfaces, it has been shown that there is a step-wise process, with a whole range of metastable species formed above 80 K. By contrast, at copper surfaces the chemistry is less complex, the most significant species being CO2- (a); these form preferentially under conditions which favour high surface concentrations of CO2(a) and therefore co-operative effects within the adlayer. The need to develop experimental methods for studying surface processes at high pressures is well recognised, however the present work shows that for some systems low temperatures (and pressures) offer a possible alternative strategy for delineating the step-wise nature of the reaction.