Enhanced reactivity of oxygen-functionalised PAHs with atomic hydrogen – A route to the formation of small oxygen-carrying molecules
Open Access
- 26 July 2022
- journal article
- research article
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 663, A136
- https://doi.org/10.1051/0004-6361/202243312
Abstract
Aims. We investigate the interaction of a linear, catacondensed polycyclic aromatic hydrocarbon (PAH), pentacene (C22H14), and its oxygen-functionalised form 6, 13 pentacenequinone (C22H12O2) with atomic hydrogen (H) under interstellar conditions. We compare their reaction cross-sections and reaction products to elucidate the possible role played by oxygen-functionalised PAHs in the formation of small oxygen-carrying molecules in the interstellar medium.Methods. We present temperature-programmed desorption measurements in combination with mass spectrometry. The evolution of the mass distribution of the desorbed species with increasing H-atom fluence and their peak desorption temperatures give insight into the reaction products.Results. The experiments reveal reaction cross-sections that are significantly larger for the oxygen-functionalised species compared to pentacene. For both pentacene and 6, 13 pentacenequinone, hydrogenated species with an even number of excess H-atoms dominate over hydrogenated species with an odd number of H-atoms. The end product, after exposure to large H-atom fluences, for both pentacene and PQ is fully superhydrogenated pentacene (C22H36), with little evidence for any remaining oxygen-containing species. This suggests the release of small molecules such as OH and/or H2O by the abstraction of oxygen atoms during hydrogenation, indicating that oxygen-functionalised PAHs can enable the formation of small oxygen-bearing molecules under interstellar conditions.Keywords
Funding Information
- EU Horizon2020 Marie Skłodowska-Curie ITN (722346)
- Danish National Research Foundation (DNRF150)
- Danish Council for Independent Research (5137-00049B)
- European Research Council (648551)
This publication has 51 references indexed in Scilit:
- Formation of buckminsterfullerene (C 60 ) in interstellar spaceProceedings of the National Academy of Sciences of the United States of America, 2011
- PAHS AND ASTROBIOLOGYEAS Publications Series, 2011
- Photochemistry of polycyclic aromatic hydrocarbons in cosmic water iceAstronomy & Astrophysics, 2010
- MOLECULAR HYDROGEN FORMATION CATALYZED BY POLYCYCLIC AROMATIC HYDROCARBONS IN THE INTERSTELLAR MEDIUMThe Astrophysical Journal, 2009
- Design and characterization of a thermal hydrogen atom sourceJournal of Applied Physics, 2008
- PAHs in Astronomy - A ReviewProceedings of the International Astronomical Union, 2008
- Effect of impurities on the mobility of single crystal pentaceneApplied Physics Letters, 2004
- Pentacene thin film transistors on inorganic dielectrics: Morphology, structural properties, and electronic transportJournal of Applied Physics, 2003
- Intensity of a source of atomic hydrogen based on a hot capillaryJournal of Applied Physics, 2000
- Formation of an atomic hydrogen beam by a hot capillaryJournal of Applied Physics, 1998