Molecular hydrogen formation on interstellar PAHs through Eley–Rideal abstraction reactions. Issue 1 (11th June 2018)

• Record Type: Journal Article
• Authors: Foley, Nolan; Cazaux, S; Egorov, D; Boschman, L M P V; Hoekstra, R; Schlathölter, T
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 479:Issue 1(2018)
• Page Start: 649
• Page End: 656
• Publication Date: 2018-06-11
• Subjects: astrochemistry -- molecular processes -- ISM: molecules; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty1528
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present experimental data on H2 formation processes on gas-phase polycyclic aromatic hydrocarbon (PAH) cations. This process was studied by exposing coronene radical cations, confined in a radio-frequency ion trap, to gas-phase H atoms. Sequential attachment of up to 23 hydrogen atoms has been observed. Exposure to atomic D instead of H allows one to distinguish attachment from competing abstraction reactions, as the latter now leave a unique fingerprint in the measured mass spectra. Modelling of the experimental results using realistic cross-sections and barriers for attachment and abstraction yield a 1:2 ratio of abstraction to attachment cross-sections. The strong contribution of abstraction indicates that H2 formation on interstellar PAH cations is an order of magnitude more relevant than previously thought.