X-ray and UV photoelectron spectroscopy study of Na–halogen–graphite intercalation compounds. Comparison between donor- and acceptor-graphite compounds

New results obtained with XPS and UPS on ternary Na–halogen–graphite intercalation compounds (GICs) complement previous ones obtained on binary alkali- and ternary alkali–oxygen–GICs yet published, to give a general overview about what can be learned from photo-electron spectroscopy. In addition to surface stoichiometry, the charge transfer, the Fermi level energy shift and the band structure are estimated thanks to the observation in UP spectra of the unoccupied Π∗ level peak.