High-resolution electron-momentum spectroscopy of the valence orbitals of the benzene molecule

The binding-energy spectrum and electron-momentum spectra of valence orbitals of benzene were measured via a high-resolution electron-momentum spectrometer at incident energies of 600 and 1200 eV plus the binding energy. The experimental momentum profiles were compared with the results from a plane-wave impulse approximation (PWIA) calculation using Dyson orbitals obtained from symmetry-adapted-cluster configuration-interaction calculations. For the ${1e}_{1\mathrm{g}}, {3e}_{2\mathrm{g}}, {3e}_{1\mathrm{u}}$, and ${2b}_{1\mathrm{u}}$ orbitals, the discrepancy between the experimental distributions and the PWIA calculations was tentatively assigned to the distorted wave effects. The current high-resolution electron-momentum spectroscopy results provide the experimental benchmark for rigorous distorted-wave calculations about benzene in the future.