REACTION OF ATOMIC OXYGEN WITH ADSORBED CARBON-MONOXIDE ON A PLATINUMSURFACE

The reaction of gas-phase oxygen atoms with carbon monoxide molecules adsorbed on a platinum surface is studied by the use of the classical trajectory approach. Collisions taking place at gas temperature 300 K are considered as a function of the incident angle. Gas atoms approach ing CO in the angle range of 0 degrees-50 degrees are very efficient a t producing vibrationally excited CO2 molecules in the gas phase. Beyo nd 50 degrees, the extent of desorbing CO2 formation decreases rapidly and becomes negligible as the incident angle approaches 90 degrees. M ost of the exothermicity of the reaction O+CO-->CO2 minus the CO-surfa ce-binding energy appears to be transferred to the asymmetric stretchi ng vibration of the desorbing CO2. The fraction of reactive collisions producing molecules having vibrational energies corresponding to leve ls upsilon(3)=9 to 13 is found to be very high and exhibits a vibratio nal population inversion. Molecular time scale trajectory calculations show that relatively few atoms making up the solid are needed to obta in reliable data on energy transfer to the solid. The behavior of ense mbles at various reaction times is discussed in detail. The surface is considered to be at 0 K. (C) 1996 American Institute of Physics.