In-plane charge distribution in potassium-intercalated graphite

Carbon-core-electron binding energies, measured with the use of x-ray photoelectron spectroscopy, give direct information on the distribution of the transferred electronic charge in graphite intercalation compounds. Both the stage-one and stage-two compounds, K${\mathrm{C}}_8$ and K${\mathrm{C}}_{24}$, with all carbon atoms in bounding layers, should be well suited to the study of the in-plane charge distribution; however, cleaved samples of K${\mathrm{C}}_8$ proved to be extremely unstable at room temperature in ultrahigh vacuum. For the stage-two compound, the C $1s$ spectra reveal an electronic charge distribution which is very strongly localized on those carbon atoms which are nearest the intercalant ions.