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| molecules:ism:c3h5cn [2022/07/28 12:28] – mueller | molecules:ism:c3h5cn [2024/01/31 12:42] (current) – mueller |
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| ===== On Cyanides Derived from Propene in the ISM ===== | ===== On the Discovery of Cyanopropenes in the ISM ===== |
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| J. Cernicharo, R. Fuentetaja, C. Cabezas, M. Agúndez, N. Marcelino, B. Tercero, J. R. Pardo, and P. de Vicente\\ | J. Cernicharo, R. Fuentetaja, C. Cabezas, M. Agúndez, N. Marcelino, B. Tercero, J. R. Pardo, and P. de Vicente\\ |
| line survey]]**\\ | line survey]]**\\ |
| //Astron. Astrophys.// **663**, Art. No. L5 (2022).\\ | //Astron. Astrophys.// **663**, Art. No. L5 (2022).\\ |
| The molecular line survey is of the prototypical cold dark molecular cloud TMC-1 and was carried out with the Yebes 40 m radio telescope between 31.0 and 50.4 GHz. 2-Butenenitrile, aka 1-cyanopropene or crotononitrile, was detected in its //E// (or //trans//) and //Z// (or //cis//) stereoisomeric forms. In addition, 2-propenenitrile, aka 2-cyanopropene or methacrylonitrile was also identified as was 3-Butenenitrile, aka 3-cyanopropene or allyl cyanide, in its //syn// (or //cis//) and //gauche// conformers. | The molecular line survey is of the prototypical cold dark molecular cloud TMC-1 and was carried out with the Yebes 40 m radio telescope between 31.0 and 50.4 GHz. 2-Butenenitrile, aka 1-cyanopropene or crotononitrile, was detected in its //E// (or //trans//) and //Z// (or //cis//) stereoisomeric forms. In addition, 2-propenenitrile, aka 2-cyanopropene or methacrylonitrile was also identified as was 3-butenenitrile, aka 3-cyanopropene or allyl cyanide, in its //syn// (or //cis//) and //gauche// conformers. Please note that while the two 2-butenenitriles are counted as two molecules because conversion requires breaking of a double bond, the 3-butenenitriles are counted as one, even if the rotation around a single bond is at least somewhat hindered at the low temperatures of TMC-1. |
| Ethynylallene, aka allenylacetylene or 1,2-pentadien-4-yne, was identified through 16 unblended or slightly blended //a//-type transitions with 6 ≤ //J// ≤ 10 and //K<sub>a</sub>// ≤ 3 in the course of a molecular line survey of the prototypical cold dark molecular cloud TMC-1 carried out with the Yebes 40 m radio telescope between 32.8 and 49.2 GHz. The signal-to-noise ratio of the //K<sub>a</sub>// = 3 lines of these is on the edge, but the model supports the assignments. A value of //T//<sub>rot</sub> = 9 ± 1 K was derived through a rotation diagram, but the model is more compatible with 7 K. The column density of butenyne is about a factor of 4.5 higher than that of the isoelectronic allenyl cyanide. It is, in addition, similar to that of butenyne, a factor of 5 lower than that of the methyldiacetylene isomer (aka butadienyne), and a factor of 10 lower than that of methylacetylene (aka propyne).\\ | Several //a//-type transitions having 4 ≤ //J// ≤ 8 to 6 ≤ //J// ≤ 11 and //K<sub>a</sub>// ≤ 2 were identified. A value of //T//<sub>rot</sub> = 7 ± 1 K was derived through rotation diagrams in all instances. The column densities (in units of 10<sup>10</sup> cm<sup>−2</sup>) of the butenenitriles is about 5, 13, 10, 7, and 8 for the //E//-1-, //Z//-1-, 2-, //syn//-3-, and //gauche//-3-forms, respectively, compared to ~4 × 10<sup>13</sup> cm<sup>−2</sup> for propene. The combined cyanopropenes are much less abundant in relation to its parent hydrocarbon compared to other detected cyanide derivatives. It is also noteworthy to point out that, unsurprisingly, the abundances among the cyanopropenes do not at all reflect relative energies among these species.\\ |
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| Contributor(s): H. S. P. Müller; 07, 2022 | Contributor(s): H. S. P. Müller; 07, 2022; 01, 2024 |
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