Reactive Scattering of N2O Molecular Beams from Clean and Carbon-Covered (100) Platinum Single-Crystal Surfaces

Abstract

Thermal energy molecular beams of N2O have been scattered from a platinum (100) surface maintained in the temperature range 900–1500 K in an ultrahigh vacuum chamber. The angular distribution of the scattered beams was monitored with a quadrupole mass spectrometer, the target surface structure by low energy electron diffraction, and the composition by Auger spectroscopy. The effect of surface temperature and surface structure on the surface decomposition of N2O has been studied. At 1200 K, using a clean surface, the angular distribution of one of the reaction products, NO, follows the cosine law, but deviations from this behavior seem to occur if the surface is covered by a layer of carbon. At still higher temperatures N2O reacts with the carbon layer on the surface and removes it by the oxidation reaction N2O+C→CO+N2. The mechanisms of reactive scattering based on the experimental observations are discussed.