Dynamics of Graphite Oxidation at High Temperature

Abstract

Interactions of ground-state atomic and molecular oxygen, O(3P) and O2(3Σg–), with a highly oriented pyrolytic graphite surface were investigated for a broad range of surface temperatures from 1100 K to approximately 2300 K. A molecular beam composed of 89% O atoms and 11% O2, with average translational energies of 472.1 and 944.4 kJ mol–1, respectively, was directed at the surface with an incidence angle, θi, of 45°. Angle- and velocity-resolved distributions were collected for nonreactively and reactively scattered products with the use of a rotatable mass spectrometer detector. Four scattered products were observed: O, O2, CO, and CO2. O atoms that exited the surface without reacting exhibited both impulsive scattering (IS) and thermal desorption (TD) components. The primary reaction product observed was carbon monoxide (CO). Carbon dioxide (CO2) was measured only with surface temperatures below 1400 K, and O2 was attributed to IS of O2 that was present in the incident beam. Although there is evidence ...