C 1s photoemission and shake-up features of (C59N)2

We report on a study of the C 1s shake-up spectrum for bulk films of (C₅₉N)₂ and find a previously unobserved peak at 1.05 eV from the main line. This new peak can be attributed to the C 1s binding energy of sp²-like carbon atoms bound directly to nitrogen. We further analyse the spectrum by comparing it to a convolution of valence band and x-ray absorption spectra, which closely mimics the transitions possible in the presence of a core hole. The shake-up spectrum represents on-site excitons, and their onset is consistent with the optical gap of 1.4 eV.