Abstract
Large polycyclic aromatic hydrocarbons (PAHs) are the most abundant complex molecules in the interstellar medium; however, their possible formation pathways from small molecular species are still elusive. In the present work, we follow and characterize the formation of PAHs in an electrical discharge, specifically the PAH naphthalene in a molecular beam of argon. The fragments, products and reaction intermediates are unambiguously structurally identified by mass-selective IR-UV spectroscopy combined with quantum chemical calculations. This experiment provides evidence of the formation of larger PAHs containing up to four cyclic rings in the gas phase originating from a non-radical PAH molecule as a precursor. In addition to PAH formation, key resonance stabilized radical intermediates and intermediates containing di-acetylenic side groups are unambiguously identified in our experiment. We thereby not only reveal competing formation pathways to larger PAHs, but also identify intermediate species to PAH formation that are candidates for detection in radio-astronomy.
| Original language | English |
|---|---|
| Article number | 269 |
| Journal | Nature Communications |
| Volume | 11 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Dec 2020 |
| Externally published | Yes |
Funding
We would like to thank the FELIX laboratory team for their experimental assistance and scientific support and we acknowledge the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) for the support of the FELIX Laboratory and SURFsara (proj. 17603) for their computational resources. Furthermore, we would like to thank Prof. Dr. Harold Linnartz and Dr. Lex van der Meer for their useful discussions. At last, we thank Dr. Amanda Steber, Dr. Sébastien Gruet, and Prof. Dr. Melanie Schnell for their cooperation on developing the discharge source.