C1s shakeup spectrum of C60: Global charge-transfer satellites and their relation to the x-ray threshold singularities in macroscopic systems.

Abstract

The ${\mathrm{C}}_{1\mathit{s}}$ core photoelectron shakeup spectrum of ${\mathrm{C}}_{60}$ has been studied experimentally and theoretically. It is found that the lowest shakeup satellites correspond to global charge-transfer excitations which move charge from the opposite side of the fullerene cage to the core-hole region, while more localized excitations give rise to higher-energy satellites. This finding is in accord with a generalized version of the Mahan-Nozi\`eres--de Dominicis model of core excitation, in which a local dielectric response is included with the original adiabatic contribution.