- Resonant photoemission spectroscopy(resPES) is used to probe the occupied pi- and unoccupied pi*-bands of
carbon thin films with particular focus on the Auger decay. Highly Oriented Pyrolytic Graphite (HOPG) is
studied at the C1s edge. We find strong resonant features at 285.5 eV and 292 eV in the resPES diagram. The normal two-hole Auger decay proceeds under constant kinetic energy (451)only in the sigma*-region. In the pi*-region, however, it proceeds under 67.5° in terms of a Ebind(w) diagram. We attribute this to a multiple Auger decay with a net three hole final state. For this novel decay process we propose a model.We discuss
the long lifetime of the first resonant excitation and conclude that it arises from the strong excitonic character
of the first resonant state. We use HOPG as a reference system and suggest that this novel process is a tool to
identify interlayer–substrate interaction of the carbon layers involved.