Electronic structures of HOPG and stage-2 IBr-GIC studied by angle resolved photoemission

Angle resolved photoemission spectra (ARPES) of host HOPG and IBr-GIC have been measured at 16 K using hν=122 eV. Both HOPG and IBr-GIC show clear dispersions of upper π band and σ bands derived from C 2s and 2p electrons. The intensity plot of ARPES spectra shows the overlap of the dispersion curves along the ΓM and ΓK directions due to the in-plane mosaic structure of HOPG. Based on the Johnson–Dresselhaus band model, the dispersion curves of the π bands of HOPG and IBr-GIC are reproduced over the full Brillouin zone. We discuss the important role of the interactions between C–C atoms in the neighboring layers in the stage-2 structure.