Photodouble ionization of H2

The Coulomb explosion of the hydrogen molecule, after absorption of a 76 eV photon, has been studied by momentum imaging the two electrons and the two protons. Absolute fully differential cross sections (FDCS) are compared with Time Dependent Close Coupling (TDCC) calculations and the first-order helium-like model in the coplanar geometry for equal electron energy sharing. While the helium-like model gives a consistent agreement in shape and magnitude with experimental data, the comparison with the TDCC calculations highlights the limit of this model when the molecular axis' orientation is along the polarization direction. New evidence of changes in the FDCS with internuclear separation is reported for the coplanar geometry.