Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and first detection in the ISM
| Autor: | Bizzocchi, Luca, Prudenzano, Domenico, Rivilla, Victor M., Pietropolli-Charmet, Andrea, Giuliano, Barbara M., Caselli, Paola, Martín-Pintado, Jesus, Jiménez-Serra, Izaskun, Martín, Sergio, Requena-Torres, Miguel A., Rico-Villas, Fernando, Zeng, Shaoshan, Guillemin, Jean-Claude |
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| Rok vydání: | 2020 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202038083 |
| Popis: | Small imines containing up to three carbon atoms are present in the interstellar medium. As alkynyl compounds are abundant in this medium, propargylimine thus represents a promising candidate for a new interstellar detection. The goal of the present work is to perform a comprehensive laboratory investigation of the rotational spectrum of propargylimine in its ground vibrational state in order to obtain a highly precise set of rest-frequencies and to search it in space. The rotational spectra of $E$ and $Z$ geometrical isomers of propargylimine have been recorded in laboratory in the 83-500 GHz frequency interval. The measurements have been performed using a source-modulation millimetre-wave spectrometer equipped with a pyrolysis system for the production of unstable species. High-level ab initio calculations were performed to assist the analysis and to obtain reliable estimates for an extended set of spectroscopic quantities. The improved spectral data allow us to perform a successful search for this new imine in the quiescent G+0.693-0.027 molecular cloud. Eighteen lines of $Z$-propargylimine have been detected at level $>2.5 \sigma$, resulting in a column density estimate of $N = (0.24\pm 0.02)\times 10^{14}$ cm$^{-2}$. An upper limit was retrieved for the higher-energy $E$ isomer, which was not detected in the data. The fractional abundance (w.r.t. H$_2$) derived for $Z$-propargylimine is $1.8\times 10^{-10}$. We discuss the possible formation routes by comparing the derived abundance with those measured in the source for possible chemical precursors. Comment: 15 pages, 6 figures. Accepted for publication in Astronomy & Astrophysics |
| Databáze: | arXiv |
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