A THEORETICAL-STUDY OF THE PEROXO AND SUPEROXO FORMS OF MOLECULAR-OXYGEN ON METAL-SURFACES

Journal article, 1989

Simple cluster model calculations have been performed for the peroxo and superoxo forms of O2 on metal surfaces. The ionization spectra of superoxo-O2 on Ag(110) and Pt(111) and for peroxo-O2 on Ag(110) are predicted in good agreement with the most reliable experimental measurements. It is shown that the large qualitative difference between these spectra can be used to decide experimentally whether O2 is chemisorbed in the peroxo or superoxo form. The O---O bond distance is calculated to be 1.32 Å for superoxo-O2 and 1.43 Å for peroxo-O2 in good agreement with the most recent NEXAFS measurements on Pt(111) and Ag(110), respectively. A problem in a recent analysis of a UPS spectrum for obtaining the O---O bond distance is pointed out.