Electron-hole correlation effects in core-level spectroscopy probed by the resonant inelastic soft x-ray scattering map of C₆₀

We have employed a unique spectroscopic approach, a resonant inelastic soft x-ray scattering (RIXS) map, to identify and separate electron-hole correlation effects in core-level spectroscopy. With this approach, we are able to derive a comprehensive picture of the electronic structure, separating ground state properties (such as the HOMO-LUMO separation) from excited state properties (such as the C 1s core-exciton binding energy of C₆₀). In particular, our approach allows us to determine the difference between core- and valence exciton binding energies in C₆₀ [0.5 (±0.2) eV]. Furthermore, the RIXS map gives detailed insight into the symmetries of the intermediate and final states of the RIXS process.