Electronic structure of alkali-intercalated graphite studied by soft-x-ray emission spectroscopy

Carbon K soft-x-ray emission spectra of ${\mathrm{LiC}}_6$, ${\mathrm{KC}}_8$, and ${\mathrm{CsC}}_8$ are presented. An absolute value for the charge transfer from the alkali metal to the carbon π band is obtained. A model fit to the data reveals similar effects on both spectral shape and threshold energy, independent of the choice of the alkali-metal intercalant, and provides a measure of departures from the rigid-band approximation. An enhancement of the soft-x-ray emission spectrum near $E_{\mathrm{F}}$ is reported.