A high resolution photoemission study of surface core-level shifts in clean and oxygen-covered Ir(2 1 0) surfaces

M. J. Gladys, I. Ermanoski, G. Jackson, J. S. Quinton, J. E. Rowe, T. E. Madey

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

High resolution soft X-ray photoemission electron spectroscopy (SXPS), using synchrotron radiation, is employed to investigate 4f core-level features of four differently-prepared Ir(210) surfaces: clean planar, oxygen-covered planar, oxygen-induced faceted, and clean faceted surfaces. Surface and bulk peak identifications are supported by measurements at different photon energies (thus probing different electron escape depths) and variable emission angles. Iridium 4f7/2 photoemission spectra are fitted with Doniach-Sunjic lineshapes. The surface components are identified with core levels positioned at lower binding energies than the bulk components, in contrast to previous reports of binding energy inversion on Ir(100) (1 × 1) and (5 × 1) surfaces. For clean planar Ir(210) three surface Ir 4f7/2 features are observed with core-level shifts of -765, -529, and -281meV, with respect to the bulk; these are associated with the first, second and third layers of atoms, respectively, for atomically rough Ir(210). Adsorption of oxygen onto the planar Ir(210) surface is found to cause a suppression and shift of the surface features to higher binding energies. Annealing at T≥600K in oxygen produces a faceted surface as verified by low energy electron diffraction (LEED). A comparison of planar and faceted oxygen-covered surfaces reveals minor differences in the normal emission SXPS spectra, while grazing emission spectra exhibit differences. The SXPS spectrum of the clean, faceted Ir(210) exhibits small differences in comparison to the clean planar case, with surface features having binding energy shifts of -710, -450, and -230meV.

Original languageEnglish (US)
Pages (from-to)105-112
Number of pages8
JournalJournal of Electron Spectroscopy and Related Phenomena
Volume135
Issue number2-3
DOIs
StatePublished - Apr 1 2004
Externally publishedYes

Keywords

  • Faceting
  • Iridium
  • Low energy electron diffraction (LEED)
  • Oxygen
  • Soft X-ray photoelectron spectroscopy
  • Surface core-level shifts

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Radiation
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry

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