Photoemission from graphite: Intrinsic and self-energy effects

We report a photoemission study on high-quality single-crystal graphite epitaxially grown on SiC. The results are interpreted using independent information on the final states obtained by very-low-energy electron diffraction. Significant intrinsic photoemission and surface effects are identified, which distort the photoemission response and narrow the observed dispersion range of the $\pi$ state. We assess its true dispersion range using a model photoemission calculation. A significant dependence of the excited-state self-energy effects on the wave-function character is found. The experimental results are compared with a $\mathrm{GW}$ calculation.