Resonance ionization detection of neutral 0(2Pj) produced from stimulated surface processes

T. M. Orlando, A. R. Burns, E. B. Stechel, D. R. Jennison

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10 Citations (Scopus)

Abstract

We report the first quantum-state specific detection of ground-state atomic oxygen 0(3P) above an electron irradiated adsorbate-covered surface using laser resonance-enhanced multiphoton ionization spectroscopy. Electron-stimulated desorption of O(3P., is not observed from an O-covered Pt(111) surface, but 0(3P) fragments are produced from electron-stimulated dissociation of NO2(fl) coadsorbed with O (#o=0.75 ML) on Pt(111). The 9-10 eV threshold for O(3P,) formation correlates with that observed for NO2(fl) dissociation. The measured OCPj) spin-orbit state distribution is (5.0):(2.5): (1.0) for.1 1, and 0, respectively. This is within experimental error of the 2./ + 1 statistical (T— oo) limit. No gas phase OCPj) is detected from the stimulated dissociation of adsorbed O2 on Pt (111); however, we have utilized the O (\\\\\\\\P,) detection capability as an indirect probe of NO2 production from an electron-stimulatedsurface reaction between coadsorbed O2 and NO on Pt (The NO2 is detected by laser photolysis above the surface. The — 10-eV NO2 production threshold correlates with dissociative ionization from the 3agmolecularbonding orbital of O2{a). Dissociative ionization can produce energetic O atoms which may then react with a coadsorbed NO, producing an NO2 desorbate.

Original languageEnglish
Pages (from-to)1769-1773
Number of pages5
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume9
Issue number3
DOIs
Publication statusPublished - May 1991

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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