The internal energy distribution of C0
2 produced and desorbed in the steady-state CO oxidation (∼10
-2 Torr) on well-defined single crystal Pd surfaces were successfully measured by using infrared (IR) chemiluminescence technique. The CO
2 molecules produced on flat surface such as Pd(111) were highly excited (especially in terms of bending mode) than those on Pd(110) (1×1) which has atomically rough surface. These results show that the dynamics of CO oxidation on Pd surfaces is structure-sensitive. The difference in the vibrational distribution of the desorbing CO
2 indicates that a structure of activated complex of CO
2 is more bent on Pd(111) and relatively linear on Pd(110). Also, the kinetics of the steady-state CO oxidation is structure-sensitive. Furthermore, the IR chemiluminescence technique was applied to the study of CO
2 on Pd(335) having both (111) terrace and step properties. The IR study on Pd(335) revealed that the steady-state CO oxidation is proceeding at step sites under higher surface temperature condition (850 K), and the active site of CO+O recombination reaction shifts to the terrace site with increasing CO coverage.
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