Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation.
Polycyclic aromatic hydrocarbons as well as other organic molecules appear among the most abundant observed species in interstellar space and are key molecules to understanding the prebiotic roots of life. However, their existence and abundance in space remain a puzzle. Here we present a new top-down route to form polycyclic aromatic hydrocarbons in large quantities in space. We show that aromatic species can be efficiently formed on the graphitized surface of the abundant silicon carbide stardust on exposure to atomic hydrogen under pressure and temperature conditions analogous to those of the interstellar medium. To this aim, we mimic the circumstellar environment using ultra-high vacuum chambers and investigate the SiC surface by in situ advanced characterization techniques combined with first-principles molecular dynamics calculations. These results suggest that top-down routes are crucial to astrochemistry to explain the abundance of organic species and to uncover the origin of unidentified infrared emission features from advanced observations.
Centro de Astrobiología INTA-CSIC, Carretera de Ajalvir, km.4, ES-28850 Madrid, Spain.
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Merino
Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, CZ-16200 Prague, Czech Republic.
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Švec
Instituto Ciencia de Materiales de Madrid-CSIC, c/. Sor Juana Inés de la Cruz, 3, ES-28049 Madrid, Spain.
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Martinez
Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, CZ-16200 Prague, Czech Republic.
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Jelinek
Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, S.S. 14, Km 163.5, I-34149 Trieste, Italy.
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Lacovig
Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, S.S. 14, Km 163.5, I-34149 Trieste, Italy.
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Dalmiglio
Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, S.S. 14, Km 163.5, I-34149 Trieste, Italy.
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Lizzit
1] Commissariat à l'Energie Atomique et aux Energies Alternatives, SIMA, DSM-IRAMIS-SPEC, Bât. 462, 91191 Gif sur Yvette, France [2] Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France.
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Soukiassian
Centro de Astrobiología INTA-CSIC, Carretera de Ajalvir, km.4, ES-28850 Madrid, Spain.
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Cernicharo
1] Centro de Astrobiología INTA-CSIC, Carretera de Ajalvir, km.4, ES-28850 Madrid, Spain [2] Instituto Ciencia de Materiales de Madrid-CSIC, c/. Sor Juana Inés de la Cruz, 3, ES-28049 Madrid, Spain.
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Martin-Gago