Carbon 1s electron momentum spectroscopy of CF₄

We report an electron momentum spectroscopy study on the carbon 1s ionization of the CF₄ molecule. The experiment was performed in the symmetric noncoplanar geometry with an incident electron energy of 2.3 keV being employed. The measured (e, 2e) cross sections are presented as a function of the ion recoil momentum. They are also employed to make a comparison with distorted wave calculations using a Hartree-Fock wavefunction for the carbon 1s atomic orbital as well as the plane wave impulse approximation (PWIA) theory. It is found that the distorted wave calculations are inferior to PWIA in reproducing the experimental results, indicating the need for extensive studies on the core orbital ionization of molecules at large momentum transfer both experimentally and theoretically.