Fermi-Level Lowering and the Core Exciton Spectrum of Intercalated Graphite

The lowering of the Fermi energy in stage-1 FeCl₃-intercalated graphite is directly measured in the spectrum of electronic excitations from carbon 1s core states to empty carbon 2p states which appear after intercalation. The shape of the core exciton spectrum is related to the initial distribution of empty states in a formulation of the core exciton problem which includes the effect of electronic relaxation near the core hole.