{
  "abstract": "Acetylene (C$_2$H$_2$) is commonly observed in star-forming regions, young stellar objects, and the Solar System. Laboratory and theoretical studies have linked this simplest alkyne to volatile hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) through UV- or cosmic-ray-driven chemistry, but it remains unclear whether refractory material can efficiently form through solid-state reactions of C$_2$H$_2$ on dust grains. We experimentally investigate the chemical complexity induced by UV irradiation of pure C$_2$H$_2$ ice and characterize both volatile and nonvolatile photoproducts. Experiments were performed with MATRI$^2$CES under ultra-high-vacuum conditions at 15 K using 7.2--10.2 eV photons. UV-processed ices were monitored in situ by laser desorption post-ionization reflection time-of-flight mass spectrometry (LDPI ReTOF-MS) combined with pulsed ion deflection (PID). Volatile and refractory products were measured in situ at 15 and 300 K, respectively. After a fluence of $3 \\times 10^{17}$ photons cm$^{-2}$, corresponding to about $10^6$ years in dense clouds, large saturated and unsaturated hydrocarbons containing up to 13 carbon atoms are formed. After sublimation of the volatile products, the 300 K residue shows a rich and distinct mass spectrum consistent with refractory material containing conjugated triple (-C$\\equiv$C-) and double (-C=C-) bonds. These results demonstrate that UV processing of pure C$_2$H$_2$ ice can produce substantial molecular complexity and refractory hydrocarbons under astronomically relevant conditions, with possible implications for unidentified infrared emission bands.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Astronomy & Astrophysics, 705, A229 (2026)",
  "arxiv": "2609.17867",
  "author_total": 8,
  "authors": [
    {
      "name": "P. Samarth"
    },
    {
      "name": "G. Fedoseev"
    },
    {
      "name": "M. Bulak"
    },
    {
      "name": "S. Ioppolo"
    },
    {
      "name": "L. Hornekær"
    },
    {
      "name": "E. F. van Dishoeck"
    },
    {
      "name": "H. Linnartz"
    },
    {
      "name": "K. -J. Chuang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/a2zpqcw3ethk1.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.17867",
  "fulltext_url": null,
  "id": "a2zpqcw3ethk1",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.17867",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.17867",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-15",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/a2zpqcw3ethk1.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:01Z",
      "native_id": "2609.17867",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.17867"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "In situ characterization of volatile and refractory hydrocarbons produced by UV photolysis of interstellar C$_2$H$_2$ ice",
  "title_text": "In situ characterization of volatile and refractory hydrocarbons produced by UV photolysis of interstellar C_2H_2 ice",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:01Z",
  "url": "https://research.draconitic.com/paper/a2zpqcw3ethk1",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1051/0004-6361/202556672",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}