STRUCTURE-SENSITIVITY IN THE DYNAMICS OF CO OXIDATION OVER Pd SURFACES: INFRARED CHEMHEMILUMINESCENCE OF THE PRODUCT CO2

Abstract

Infrared-chemiluminescence spectra of CO 2 molecules formed by steady-state CO oxidation on Pd (111), Pd (110), Pd (100) and polycrystalline- Pd surfaces have been measured to get information on the surface reaction dynamics. In all cases, the product CO 2 was vibrationally and rotationally excited. The CO 2 molecules desorbed from Pd (100) and Pd (111), which have flat surfaces, were vibrationally more excited than those from Pd (110) (stepped surface) and polycrystalline Pd . These results show that the dynamics of CO oxidation on Pd surfaces are structure-sensitive, i.e. the structure of the activated CO 2 complex depends on the surface structures of the reaction sites. Furthermore, the activities of steady-state CO oxidation as a function of surface temperature were different among these Pd surfaces, which indicates that the CO oxidation on Pd is also structure-sensitive in the kinetics.