High-resolution electron spectroscopy of a strongly correlated system: Atomic barium

Abstract

High-resolution $4d$ and $5p$ photoelectron spectra of free barium atoms were measured using narrow-band-width synchrotron radiation of 131.2 eV photon energy. These measurements were necessary to disentangle the complex structure of the electron spectra. We also performed a Hartree-Fock calculation with relativistic corrections. A very good agreement between theory and experiment was found, which allowed the assignment of all but the weakest lines, in addition to pointing out the significant contribution of configuration interaction and shake processes.