Momentum-resolved non-resonant inelastic x-ray scattering study of C60.

For large molecular systems such as C60, accurate ab initio calculations remain challenging, making experimental methods a more reliable alternative. In this work, we employed the non-resonant inelastic x-ray scattering technique to study the electronic excitation dynamics of C60. The measurements spanned a momentum transfer range of 0.63-5.10 a.u. at a photon energy of ∼10 keV with an energy resolution around 1.0 eV. The dynamic structure factors in the excitation energy range of 5-500 eV and the generalized oscillator strengths for the core excitations of π*←1s were determined on absolute scales. A new feature at ∼24 eV was identified. In addition, the optical oscillator strengths were obtained by extrapolating the generalized oscillator strengths to zero momentum transfer, which show good agreement with the earlier x-ray absorption results. These findings demonstrate that the non-resonant inelastic x-ray scattering is a powerful technique for probing the electronic excitation process and extracting the corresponding dynamic parameters in complex molecular systems.