Momentum imaging of the photo double ionization of ethylene molecules: A kinematically complete experiment.

摘要

Direct photo double ionization (PDI) is a process in which two electrons are ejected from an atom or molecule as the result of a single photon absorption. The work presented here encompasses a complete study of PDI in a molecule. Ethylene (C2H4) was chosen to study pi electron correlation and molecular dynamics.Ethylene molecules were subjected to x-ray radiation (&sim40 eV) PDI led to the Coulomb explosion of the resulting molecular ion, the ethylene dication (C2H42+). By using the COLd Target Recoil Ion Momentum Spectroscopy technique, the recoil ions were measured in coincidence with the two ejected electrons. Three distinct dissociation channels were observed: a symmetric channel (CH2 + + CH2+), a deprotonation channel (H + + C2H3+) and an asymmetric channel (H2+ + C2H2 +).The ground state of the dication was not found in this experiment. Multiple electronic states of the dication were involved and there were various non-adiabatic pathways that controlled the dissociation dynamics. The angular distributions were constructed from the experimental measurements and they are presented and compared with H2 in this thesis.