Contribution of Autoionization Process on the Double Ionization Fragmentation Channel of Carbon Dioxide Molecule

We have studied the auto-ionization process happened in CO$_{2}$ molecule using photon energy below and above the double ionization threshold and a COLTRIMS setup. By populating an excited state of CO$_{2}$$^{+}$, transition may occur at the crossing point with CO$_{2}$$^{2+}$ leading to dissociation into CO$^{+}$ + O$^{+}$. By measuring in coincidence the kinetic energy release of the two ionic fragments and the energy of the two electrons detected, we are able to determine the internuclear distance at which the transition point between the intermediate state CO$_{2}$$^{+*}$ and the final state CO$_{2}$$^{2+}$ occurs. Preliminary results show very large internuclear distance at the transition point and that this latter auto-ionization may occurs at one order of magnitude larger than the (CO-O) equilibrium distance.