We have used both electron-induced soft x-ray emission and fast inelastic electron scattering to observe 1S core-level emission and absorption in graphite near threshold. Linear phonon coupling with partial relaxation is found to quantitatively explain the absorption linewidth, the emission broadening, and the unusually large difference between emission and absorption threshold energies (Stokes shift). Both emission and absorption line shapes quantitatively obey the final-state rule, which asserts that the best single-particle potential describing these many electron processes is the final-state potential.

• Received 31 August 1984

DOI:https://doi.org/10.1103/PhysRevB.31.5366