  Inelastic electron scattering by the adsorbate covered Pt(100) single crystal
surface is studied by Disappearance Potential Spectroscopy and density of
states (DOS) calculations. Two peculiar channels of elastic electron
consumption are highlighted, both related to the substrate core level
excitation coupled separately with two particular electron transitions. The
first channel affects the adsorbed layer and enables to reveal the valence
state structure of the adsorbed species as well as the substrate DOS. The
second one includes the multiple plasmon oscillations. The proposed mechanism
of electron transitions assumes that one-dimensional DOS at the vacuum level is
an additional spot for location of excited electrons, along with vacant DOS at
the Fermi level. Observed phenomena are supposed to be a general regularity of
electron-solid interaction and a useful tool for fingerprinting the adsorbed
layer at molecular level.
