A combined experimental and theoretical study on the formation of interstellar C3H isomers

• Published in: Science (American Association for the Advancement of Science) Vol. 274; no. 5292; pp. 1508 - 1511
• Main Authors: KAISER, R. I, OCHSENFELD, C, HEAD-GORDON, M, LEE, Y. T, SUITS, A. G
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 29.11.1996
• Subjects: Acetylene - chemistry; Astronomical Phenomena; Astronomy; Atomic, molecular, chemical, and grain processes; Carbon - chemistry; Composition; Cosmic Dust; Cosmochemistry; Earth, ocean, space; Exact sciences and technology; Fundamental aspects of astrophysics; Fundamental astronomy and astrophysics. Instrumentation, techniques, and astronomical observations; Hydrocarbons - chemistry; Hydrogen - chemistry; Interstellar matter; Interstellar medium; Interstellar medium (ism) and nebulae in milky way; Isomerism; Molecular and chemical processes and interactions; Space life sciences; Stellar systems. Galactic and extragalactic objects and systems. The universe; Molecular process; Ground states; Linear molecule; Interstellar molecules; Chemical reactions; Experimental study; Carbon; Isomers; Acetylene; Dark clouds; Atom molecule reaction; Cyclic compound; Circumstellar shells; Ab initio calculations; Interstellar clouds
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.274.5292.1508

The reaction of ground-state carbon atoms with acetylene was studied under single-collision conditions in crossed beam experiments to investigate the chemical dynamics of forming cyclic and linear C3H isomers (c-C3H and l-C3H, respectively) in interstellar environments via an atom-neutral reaction. Combined state-of-the-art ab initio calculations and experimental identification of the carbon-hydrogen exchange channel to both isomers classify this reaction as an important alternative to ion-molecule encounters to synthesize C3H radicals in the interstellar medium. These findings strongly correlate with astronomical observations and explain a higher [c-C3H]/[l-C3H] ratio in the dark cloud TMC-1 than in the carbon star IRC+10216.