Synthesis of Interstellar Benzene: A Molecular Evolution
Explore the elusive formation of benzene in cold molecular clouds using crossed molecular beam experiments and novel astrochemical models. Unveiling the key role of the ethynyl radical and 1,3-butadiene in benzene synthesis under single collision conditions.
Synthesis of Interstellar Benzene: A Molecular Evolution
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Presentation Transcript
Unraveling the Formation of Interstellar Benzene. Ralf I. Kaiser, University of Hawaii at Manoa, Honolulu, HI, 96822 Polycyclic aromatic hydrocarbons (PAHs) and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block - the aromatic benzene molecule – has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C6H6) can be synthesized via the barrier-less, exoergic reaction of the ethynyl radical (C2H) and 1,3-butadiene (H2CCHCHCH2) under single collision conditions. Novel gas–grain astrochemical models imply that this low-temperature route controls the synthesis of the very first aromatic ring from acyclic precursors in cold molecular clouds such as in TMC-1. B. M. Jones, F. Zhang, R. I. Kaiser, A. M. Mebel, M. A. Cordiner, S.B. Charnley, Unraveling the Formation of Interstellar Benzene. PNAS, 108, 452-457 (2011).