  We have used s- and p-polarized synchrotron radiation to image the electronic
structure of epitaxial graphene near the K-point by angular resolved
photoemission spectroscopy (ARPES). Part of the experimental Fermi surface is
suppressed due to the interference of photoelectrons emitted from the two
equivalent carbon atoms per unit cell of graphene's honeycomb lattice. Here we
show that by rotating the polarization vector, we are able to illuminate this
'dark corridor' indicating that the present theoretical understanding is
oversimplified. Our measurements are supported by first-principles
photoemission calculations, which reveal that the observed effect persists in
the low photon energy regime.
