Kinetics measurements of CO photo-oxidation on Pt(111). Tripa, C. Emil, Surface Science Center, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260; Arumaninayagam, Christopher R., Department of Chemistry, Wellesley College, Wellesley, Massachusetts 02181; John T. Yates, Jr. Surface Science Center, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260. J. Chem. Phys. (1996), 105(4), 1691-1696.

Abstract

The photoactivation of chemisorbed O₂ in the presence of chemisorbed CO on Pt(111) has been investigated for uv light in the range 3.87–4.77 eV (260–320 nm). Three photoprocesses first-order in O₂ coverage have been separated and for the first time the cross sections for each are reported. The dominant process is O₂ photodissociation (Q_diss=4.0±0.1×10–21 cm²). The second most probable process is photodesorption (Q_des=2.2±0.1×10–21 cm²). The least probable process is photoreaction with chemisorbed CO (Q_rxn=0.35±0.03×10–21 cm²). Previous studies of Q_rxn have reported cross sections as high as 5×10–17 cm².