Molecular oxygen, O 2 , is vital to life on Earth and possibly also on exoplanets. Although the biogenic processes leading to its accumulation in Earth’s atmosphere are well understood, its abiotic origin is still not fully established. Here, we report combined experimental and theoretical evidence for electronic state–selective production of O 2 from SO 2 , a chemical constituent of many planetary atmospheres and one that played an important part on Earth in the Great Oxidation Event. The O 2 production involves dissociative double ionization of SO 2 leading to efficient formation of the O 2 + ion, which can be converted to abiotic O 2 by electron neutralization or by charge exchange. This formation process may contribute substantially to the abundance of O 2 and related ions in planetary atmospheres, such as the Jovian moons Io, Europa, and Ganymede. We suggest that this sort of ionic pathway for the formation of abiotic O 2 involving multiply charged molecular ion decomposition may also exist for other atmospheric and planetary molecules.

Double and triple ionization of allene are investigated using electron-electron, ion-ion, electron-electron-ion and electron-electron-ion-ion (ee, ii, eei, eeii) coincidence spectroscopies at selected photon energies. The results provide supporting evidence for...

The dissociation of OCS2+ ions formed by photoionization of the neutral molecule at 40.81 eV is examined using threefold and fourfold electron-ion coincidence spectroscopy combined with high level quantum chemical...

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Conventional electron spectroscopy is an established one-electron-at-the-time method for revealing the electronic structure and dynamics of either valence or inner shell ionized systems. By combining an electron-electron coincidence technique with the use of soft X-radiation we have measured a double ionisation spectrum of the allene molecule in which one electron is removed from a C1s core orbital and one from a valence orbital, well beyond Siegbahns Electron-Spectroscopy-for-Chemical-Analysis method. This core-valence double ionisation spectrum shows the effect of symmetry breaking in an extraordinary way, when the core electron is ejected from one of the two outer carbon atoms. To explain the spectrum we present a new theoretical approach combining the benefits of a full self-consistent field approach with those of perturbation methods and multi-configurational techniques, thus establishing a powerful tool to reveal molecular orbital symmetry breaking on such an organic molecule, going beyond Löwdins standard definition of electron correlation.