Formation of complex organic molecules in molecular clouds
| Autor: | C. Scirè, G. A. Baratta, Th. Henning, K.-J. Chuang, Cornelia Jäger, Maria Elisabetta Palumbo, Harold Linnartz, Gleb Fedoseev |
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| Přispěvatelé: | ITA, DEU, NLD, RUS |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
010504 meteorology & atmospheric sciences
STAR-FORMING REGION Ketene Astrophysics Radiation chemistry Photochemistry 7. Clean energy 01 natural sciences ISOTOPE LABELING EXPERIMENTS Laboratory chemistry.chemical_compound MOLECULES Methods Solar and Stellar Astrophysics 010303 astronomy & astrophysics FREE RADICALS RADIOLYSIS Astrochemistry Molecular Processes Physics ASTROCHEMISTRY Astrophysics of Galaxies ETHYLENE Cosmic Rays 3. Good health Astrophysics - Solar and Stellar Astrophysics LABORATORY: SOLID STATE [METHODS] Infrared PRODUCT COMPOSITION ISM [INFRARED] Vinyl alcohol RADIATION CHEMISTRY LABORATORY MEASUREMENTS SATURATED HYDROCARBONS Infrared spectroscopy PETROLEUM TAR FOS: Physical sciences SIMULTANEOUS DETECTION Physics - Chemical Physics 0103 physical sciences CHEMICAL DETECTION ETHANOL ACETALDEHYDE Solar and Stellar Astrophysics (astro-ph.SR) ISM 0105 earth and related environmental sciences Chemical Physics (physics.chem-ph) Ethanol Chemical Physics COSMIC RAY MEASUREMENT FOURIER TRANSFORM INFRARED SPECTROSCOPY REACTION CROSS-SECTION COMPLEX ORGANIC MOLECULES ICE Acetaldehyde Astronomy and Astrophysics COSMIC RAYS Molecules Astrophysics - Astrophysics of Galaxies chemistry Solid State 13. Climate action Space and Planetary Science MOLECULES [ISM] COSMOLOGY Astrophysics of Galaxies (astro-ph.GA) Radiolysis MOLECULAR PROCESSES |
| Zdroj: | Astronomy & Astrophysics, 650 Astron. Astrophys. Astronomy and Astrophysics |
| Popis: | The simultaneous detection of organic molecules of the form C$_2$H$_{\text{n}}$O, such as ketene (CH$_2$CO), acetaldehyde (CH$_3$CHO), and ethanol (CH$_3$CH$_2$OH), toward early star-forming regions offers hints of shared chemical history. Several reaction routes have been proposed and experimentally verified under various interstellar conditions to explain the formation pathways involved. Most noticeably, the non-energetic processing of C$_2$H$_2$ ice with OH-radicals and H-atoms was shown to provide formation routes to ketene, acetaldehyde, ethanol, and vinyl alcohol (CH$_2$CHOH) along the H$_2$O formation sequence on grain surfaces. In this work, the non-energetic formation scheme is extended with laboratory measurements focusing on the energetic counterpart, induced by cosmic rays penetrating the H$_2$O-rich ice mantle. The focus here is on the H$^+$ radiolysis of interstellar C$_2$H$_2$:H$_2$O ice analogs at 17 K. Ultra-high vacuum experiments were performed to investigate the 200 keV H$^+$ radiolysis chemistry of predeposited C$_2$H$_2$:H$_2$O ices, both as mixed and layered geometries. Fourier-transform infrared spectroscopy was used to monitor in situ newly formed species as a function of the accumulated energy dose (or H$^+$ fluence). The infrared (IR) spectral assignments are further confirmed in isotope labeling experiments using H$_2$$^{18}$O. The energetic processing of C$_2$H$_2$:H$_2$O ice not only results in the formation of (semi-) saturated hydrocarbons (C$_2$H$_4$ and C$_2$H$_6$) and polyynes as well as cumulenes (C$_4$H$_2$ and C$_4$H$_4$), but it also efficiently forms O-bearing COMs, including vinyl alcohol, ketene, acetaldehyde, and ethanol, for which the reaction cross-section and product composition are derived. A clear composition transition of the product, from H-poor to H-rich species, is observed as a function of the accumulated energy dose. Comment: 14 pages, 7 figures, 2 tables |
| Databáze: | OpenAIRE |
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