  We calculate core-level spectra for pristine and doped free-standing graphene
sheets. Instructions for how to perform the calculations are given in detail.
Although pristine graphene is not metallic the core-level spectrum presents
low-energy tailing which is characteristic of metallic systems. The peak shapes
vary with doping level in a characteristic way. The spectra are compared to
experiments and show good agreement. We compare to two different pristine
samples and to one doped sample. The pristine samples are one with
quasi-free-standing epitaxial graphene on SiC obtained by hydrogen
intercalation and one with a suspended graphene sheet. The doped sample is a
gold supported graphene sheet. The gold substrate acts as an acceptor so the
graphene sheet gets p-doped.
