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...
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.
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...
Using time-of-flight multiple electron and ion coincidence techniques in combination with a helium gas discharge lamp and synchrotron radiation, the double ionisation spectrum of disulfur (S$$_2$$ 2 ) and the subsequent fragmentation dynamics of its dication are investigated. The S$$_2$$ 2 sample was produced by heating mercury sulfide (HgS), whose vapour at a suitably chosen temperature consists primarily of two constituents: S$$_2$$ 2 and atomic Hg. A multi-particle-coincidence technique is thus particularly useful for retrieving spectra of S$$_2$$ 2 from ionisation of the mixed vapour. The results obtained are compared with detailed calculations of the electronic structure and potential energy curves of S$$_2^{2+}$$ 2 2 + which are also presented. These computations are carried out using configuration interaction methodology. The experimental results are interpreted with and strongly supported by the computational results.
Molecular oxygen, O 2 , is vital to life on Earth and possibly on other planets. 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 major chemical constituent of many planetary atmospheres and one which played an important part on Earth in the Great Oxidation event. The O 2 production involves dissociative double ionisation of SO 2 leading to efficient formation of the O + 2 ion which can be converted to abiotic O 2 by electron neutralisation. We suggest that this formation process may contribute significantly to the abundance of O 2 and related ions in planetary atmospheres, especially in those where CO 2 , which can lead to O 2 production by different mechanisms, is not the dominant component.
Using time-of-flight multiple electron and ion coincidence techniques in combination with a helium gas discharge lamp and synchrotron radiation, the double ionisation spectrum of disulfur (S2) and the subsequent fragmentation dynamics of its dication are investigated. The S2 sample was produced by heating mercury sulfide (HgS), whose vapour at a suitably chosen temperature consists primarily of two constituents: S2 and atomic Hg. A multi-particle-coincidence technique is thus particularly useful for retrieving spectra of S2 from ionisation of the mixed vapour. The results obtained are compared with detailed calculations of the electronic structure and potential energy curves of S2+2 which are also presented. These computations are carried out using configuration interaction methodology. The experimental results are interpreted with and strongly supported by the computational results.
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