Reaction of atomic oxygen with adsorbed carbon monoxide on a platinum surface

Abstract

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 approaching CO in the angle range of 0°–50° are very efficient at producing vibrationally excited CO2 molecules in the gas phase. Beyond 50°, the extent of desorbing CO2 formation decreases rapidly and becomes negligible as the incident angle approaches 90°. Most of the exothermicity of the reaction O+CO→CO2 minus the CO–surface-binding energy appears to be transferred to the asymmetric stretching vibration of the desorbing CO2. The fraction of reactive collisions producing molecules having vibrational energies corresponding to levels v3=9 to 13 is found to be very high and exhibits a vibrational population inversion. Molecular time scale trajectory calculations show that relatively few atoms making up the solid are needed to obtain reliable data on energy transfer to the solid. The behavior of ensembles at various reaction times is discussed in detail. The surface is considered to be at 0 K.