A kinematically complete measurement of the direct photo double ionization of ethylene molecules

The absorption of a single extreme ultraviolet photon by an atom or molecule leads to the emission of two correlated electrons in the direct Photo Double Ionization (PDI) process. We investigated the PDI of single ethylene molecules near its threshold (40 eV) in order to unravel fundamental intertwining of electron correlation in inter-shell and intra-shell cases and the subsequent molecular dynamics. We particularly focused on the reaction producing a symmetric breakup of the molecule.



Using XUV photons from the Advanced Light Source coupled with a COLd Target Recoil Ion Momentum Spectroscopy setup, we were able to detect the two ejected electrons and related photo-fragments, i.e., the recoiling methylene ions in coincidence and perform a kinematically complete experiment. From the recorded data we derived the angular distributions of the emitted photoelectrons with respect to the fixed in space molecular axis and the linear polarization of the incoming light to deduce the electronic correlation in a molecular system which comprises single sigma and pi covalent bonding between the two carbon atoms. Electron-ion and electron-electron energy correlation maps along with molecular frame photo electron angular distributions for different energy sharing scenarios will be presented.