ANGLE-RESOLVED SOFT X-RAY PHOTOEMISSION FOR THE VALENCE BAND OF GRAPHITE

Abstract

Angle-resolved photoemission in the soft X-ray region has so far been used to study crystal (surface) structure by using photoelectron diffraction phenomena. In this energy region, the observation of the band structure was considered to be difficult, because the momentum of the incident photon cannot be negligible, the emitted electron is strongly influenced by the electron diffraction effects, and the cross section of the valence band is very small. We have performed the angle-resolved photoemission from the valence bands of highly oriented pyrolytic graphite by using the soft X-ray (hν=980 eV ) and successfully observed the band structure. The appearance of the structures of the band density of state is also discussed. Since the escape depth for the electrons with high kinetic energies is longer than ARUPS, this experimental method is better than the usual ARUPS in order to study the bulk band structures in solids.