Site-switching for CO2 formation and structural transformation of (1 x 2) reversible arrow (1 x 1) in steady-state CO oxidation on Pt(110)

The angular and velocity distributions of desorbing product CO2 were studie d in steady-state CO oxidation on Pt(1 1 0) by means of cross-correlation t ime-of-flight techniques. In the active region where the reaction was first order in CO, the angular distribution in the (0 0 1) plane was split into two-directional lobes collimated at +/- 25 degrees from the surface-normal direction, indicating the CO2 formation on inclined (1 1 1) terraces. The t ranslational temperature was maximized at these collimation angles, reachin g about 1820 K. On the other hand, in a limited range of the inhibited regi on, where CO retarded the reaction, CO2 desorption sharply collimated along the surface-normal direction, suggesting CO2 formation on flat (1 x 1) dom ains. (C) 2001 Elsevier Science B.V. All rights reserved.