{
  "id": "2404.03334",
  "version": "v1",
  "published": "2024-04-04T10:02:18.000Z",
  "updated": "2024-04-04T10:02:18.000Z",
  "title": "First detection in space of the high-energy isomer of cyanomethanimine: H2CNCN",
  "authors": [
    "David San Andrés",
    "Víctor M. Rivilla",
    "Laura Colzi",
    "Izaskun Jiménez-Serra",
    "Jesús Martín-Pintado",
    "Andrés Megías",
    "Álvaro López-Gallifa",
    "Antonio Martínez-Henares",
    "Sarah Massalkhi",
    "Shaoshan Zeng",
    "Miguel Sanz-Novo",
    "Belén Tercero",
    "Pablo de Vicente",
    "Sergio Martín",
    "Miguel A. Requena-Torres",
    "Germán Molpeceres",
    "Juan García de la Concepción"
  ],
  "comment": "22 pages, 8 figures, 3 tables, 2 appendix - Accepted for publication in The Astrophysical Journal",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We report the first detection in the interstellar medium of $N$-cyanomethanimine (H$_2$CNCN), the stable dimer of HCN of highest energy, and the most complex organic molecule identified in space containing the prebiotically relevant NCN backbone. We have identified a plethora of $a$-type rotational transitions with 3 $\\leq J_\\text{up} \\leq$ 11 and $K_\\text{a} \\leq$ 2 that belong to this species towards the Galactic Center G+0.693-0.027 molecular cloud, the only interstellar source showing the three cyanomethanimine isomers (including the $Z$- and $E$- isomers of $C$-cyanomethanimine, HNCHCN). We have derived a total column density for H$_2$CNCN of (2.9$\\, \\pm \\,$0.1)$\\times$10$^{12}$ cm$^{-2}$, which translates into a total molecular abundance with respect to H$_2$ of (2.1$\\, \\pm \\,$0.3)$\\times$10$^{-11}$. We have also revisited the previous detection of $E$- and $Z$-HNCHCN, and found a total $C/N$-cyanomethanimine abundance ratio of 31.8$\\, \\pm \\,$1.8 and a $Z/E$-HNCHCN ratio of 4.5$\\, \\pm \\,$0.2. While the latter can be explained on the basis of thermodynamic equilibrium, chemical kinetics are more likely responsible for the observed $C/N$-cyanomethanimine abundance ratio, where the gas-phase reaction between methanimine (CH$_2$NH) and the cyanogen radical (CN) arises as the primary formation route.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-04-04T10:02:18.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "first detection",
      "high-energy isomer",
      "cyanomethanimine abundance ratio",
      "prebiotically relevant ncn backbone",
      "primary formation route"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 22,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}