Theory of Desorption of Neutrals by Temporary Ionization of Physisorbed Species at Metal Surfaces

  • Z. W. Gortel
  • H. J. Kreuzer
  • P. Feulner
  • D. Menzel
Conference paper
Part of the Springer Series in Surface Sciences book series (SSSUR, volume 13)

Abstract

Electron or photon stimulated desorption (ESD or PSD, respectively) is a sensitive probe for studying atomic or molecular systems in interaction with solid surfaces /1,2/. Apart from fragment ions in some cases of physisorbed molecules, only neutral adsorbate species desorb from physisorbed layers /3–7/. This fact is understood in terms of a classical model, due to ANTONIEWICZ /8/ in which the desorption process is a sequence of three steps denoted by 1, 2, and 3 in both panels of Fig. 1. Total electronic energy of the adparticle - solid system depends on the adparticle’s distance from the solid surface and on the state of an electronic excitation the solid and the adsorbed particle are in. For physisorption the electrons in the solid and on the adparticle can be considered separately. Thus, the electronic diabatic configuration in which the solid and the adparticle are in their respective electronic ground states corresponds to the energy level VO and VO(z) is the surface potential for the physisorbed neutral. In a configuration corresponding to Vk the electrons on the adparticle and those in the solid are in the ground and in an excited state, respectively, with an excitation energy Ek for the latter. Thus, Vk(z)’s form a continuum of surface potentials filling all energies above VO(z). Finally, for the adparticle ionized by removing its valence electron and the solid in the ground state, the corresponding surface potential is \({{\text{V}}_ + }{\text{(z) + }}{{\text{I}}_\infty }\) where \({I_\infty}\) - the ionization energy of the isolated particle - was explicitly singled out from the z-dependent part.

Keywords

Auger Sorb Berman 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1988

Authors and Affiliations

  • Z. W. Gortel
    • 1
  • H. J. Kreuzer
    • 2
  • P. Feulner
    • 3
  • D. Menzel
    • 3
  1. 1.Department of PhysicsThe University of AlbertaEdmontonCanada
  2. 2.Department of PhysicsDalhousie UniversityHalifaxCanada
  3. 3.Physik-Department E20Technische Universität MünchenGarchingFed. Rep. of Germany

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