Resonant auger processes in adsorbates

We will present results of a very recent study of the electronic decay properties of resonant adsorbate core hole states performed under high resolution conditions, i.e. excitation with subnatural linewidth. Under these conditions two types of resonant Auger processes after core-to-bound excitation are observed for adsorbates, a coherent resonant 'Raman'-type channel and an incoherent 'normal' Auger-type channel. Their branching ratio can be used as a quantitative measure for the (sub-) femtosecond dynamics of charge transfer from an adsorbate resonance to the underlying substrate. Thereby the core hole lifetime serves as an 'internal' clock for measuring the dynamics of relaxation phenomena. (C) 1998 Elsevier Science B.V. All rights reserved.