X core level BE in bulk LiX / Li2X / LiX3 BE in Li3X BE in Li4X indicating that the charge donated by the additional Li is largely transferred to the graphite substrate. Exceptions are the N1s and S2p levels in LixN and LixS, respectively, where the differences in BE are about 1 eV. Furthermore, the BEs calculated for these structures closely resemble those obtained in recent calculations of anions X in the respective bulk structures, indicating that the interaction with graphite has little influence on the core level BEs of these species as compared to the respective bulk environment. Only for LiF we find a significant difference. Most likely, this discrepancy is due to the failure of the GGA functional to accurately describe the position the valence band of such systems with large band gaps. For comparison with the experimental spectra, we also included the calculated BEs of the Li3X and Li4X species as colored symbols in Figure , similar to the approach for the coadsorbed species and initial reaction products discussed before. The calculated BEs generally agree quite well with the BEs of the low-BE peaks formed during post-deposition of Li and in particular during the annealing sequence. It should be noted, however, that the correlation is not unique, in the sense that for some states such as F1s or N1s also a molecular species (BMP-Li2NSO2CF3SO2 / LiCF3) shows a signal in the low BE range., while for the O1s and S2p signals only the binary compound feature signals in this BE range. Hence, in these cases we can unambiguously conclude on the presence of these adsorbed binary components once these low-BE peaks appear. Furthermore, for the LixN species we obtained a very low N1s signal with a BE of only 393.9 eV (Li4N) or 394.8 eV (N3Li), which is well below the low BE NTFSI,dec-2 peak in the spectra at 398.9 eV (Figure ). Based on this discrepancy and from the fact that adsorbed LiCN shows a calculated N1s signal at 399.0 eV (Table ), we postulate that the binary compound in the low-BE peak (NTFSI,dec-2) is related to the formation of LiCN rather than of Li3N.