ELECTRON-SPECTROSCOPY OF ADSORBATES VIA AUTOIONIZATION OF CORE-TO-BOUND EXCITED-STATES - EXPERIMENT AND THEORY

We use autoionization Spectroscopy after core-to-bound excitation of adsorbed molecules to get information about the spectral distribution of valence electrons in adsorbates and about the nature of shake up satellite states. Examples are presented for a physisorbed system (CO2/Ni(110)), a weakly chemisorbed system (N2/Ni(110)) and a strongly chemisorbed system (CO/Ni(110)). It is shown that in the first case detailed calculations of the autolonization rates of the isolated molecule can basically explain the experimental findings. For N2/Ni(110) autoionization spectroscopy is shown to verify an assignment put forward for the photoemission spectrum, i.e. that satellites contribute heavily to the valence ionization of many systems. In the third example, the angular dependences of the autoionization lines are used to deduce Information on the symmetries of ion states. © 1990.