Photoelectron Spectroscopy and Surface Chemistry

  • A. M. Bradshaw
  • D. Menzel
Part of the The IBM Research Symposia Series book series (IRSS)

Abstract

Photoelectron spectroscopy has fulfilled much of its early promise as a useful complementary technique in surface science investigations. In the present paper we review certain aspects of recent work, in particular, the application to adsorption phenomena on single crystal surfaces. It is found that excitation with monochromatic soft X-radiation produces core level spectra which can be used to give an overview of different chemisorption states. Because the binding energies corresponding to such spectral features are often characteristic of the chemical environment of the atom concerned, it is possible, for example, to differentiate between molecular and dissociative chemisorption of molecules such as carbon monoxide and formaldehyde adsorbed on metal surfaces. Certain relaxation effects specific to adsorbed layers can be identified. The use of the method in chemisorption and oxidation kinetics is also discussed. Valence level spectra generally excited by longer wavelength radiation give information on the molecular orbitals of the adsorbate complex. A precise identification of such orbitals and thus the construction of gas phase/adsorbed phase correlation diagrams is achieved by investigating the dependence of the spectrum on energy and state of polarisation of the incoming photons as well as on the photoelectric angular distribution. The much-investigated CO|Ni (100) system is discussed here as an example. The establishment of empirical orbital energy diagrams is considered a necessary prerequisite for further progress in chemisorption theory. Recent measurements of the adsorption of unsaturated hydrocarbons on transition metals demonstrate the sensitivity of UPS in fingerprinting chemical reactions on surfaces.

Keywords

Nickel Formaldehyde Tungsten Acetylene Azimuth 

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Copyright information

© Plenum Press, New York 1978

Authors and Affiliations

  • A. M. Bradshaw
    • 1
  • D. Menzel
    • 2
  1. 1.Fritz-Haber-Institut der Max-Planck-GesellschaftBerlin 33Germany
  2. 2.Institut f. FestkörperphysikTechnischen Universität MünchenGarchingGermany

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