Irreversible energy transfer in ionization of physisorbed adsorbates II. Inelastic energy spectra of temporarily ionized adatoms

Abstract

We have studied inelastic processes following core ionization of a physisorbed adsorbate by an external probe (electron impact or photon absorption), which typically occur in the intermediate, temporary ionized adatom states of electron (ESD) or photon (PSD) stimulated desorption and XPS of adsorbates. In the ionization process the adsorbate makes a diabatic or Franck-Condon transition from the neutral state potential V (+) (r) to the ionic potential V (0) (r) in which the charge of the moving ion is coupled to the charge density fluctuations of the substrate. This suddenly switched on dynamical interaction gives rise to inelastic energy transfer from the probe and the ionized adsorbate to the substrate degrees of freedom (heat bath)