Charge transfer and the nature of empty states in potassium-intercalated graphite

Abstract

The near-edge photoabsorption spectra of graphite intercalation compounds of potassium have been measured at the energy corresponding to the K edge of potassium. Polarization of a synchrotron beam has been used to probe the local symmetry of empty states at the potassium site. As a result, peaks in the spectra for ${\mathrm{KC}}_{8}$ have been identified with the transitions to final states provided by our energy-band-structure calculation. These results along with the calculated wave functions demonstrate the hybridization between carbon and potassium orbitals in the empty bands of ${\mathrm{KC}}_{8}$. The charge transfer between potassium and graphite layers is estimated from the measurements and supported by the calculations.