SIMBAD references

2021A&A...647L..10A - Astronomy and Astrophysics, volume 647, L10-10 (2021/3-1)

Discovery of the propargyl radical (CH2CCH) in TMC-1: One of the most abundant radicals ever found and a key species for cyclization to benzene in cold dark clouds.

AGUNDEZ M., CABEZAS C., TERCERO B., MARCELINO N., GALLEGO J.D., DE VICENTE P. and CERNICHARO J.

Abstract (from CDS):

We present the first identification in interstellar space of the propargyl radical (CH2CCH). This species was observed in the cold dark cloud TMC-1 using the Yebes 40 m telescope. The six strongest hyperfine components of the 20,2-10,1 rotational transition, lying at 37.46GHz, were detected with signal-to-noise ratios from 4.6σ to 12.3σ. We derived a column density of 8.7x1013cm–2 for CH2CCH, which translates to a fractional abundance relative to H2 of 8.7x10–9. This radical has a similar abundance as methyl acetylene, with an abundance ratio CH2CCH/CH3CCH close to one. The propargyl radical is thus one of the most abundant radicals detected in TMC-1, and it is probably the most abundant organic radical with a certain chemical complexity ever found in a cold dark cloud. We constructed a gas-phase chemical model and find calculated abundances that agree with, or fall two orders of magnitude below, the observed value depending on the poorly constrained low-temperature reactivity of CH2CCH with neutral atoms. According to the chemical model, the propargyl radical is essentially formed by the C + C2H4 reaction and by the dissociative recombination of C3Hn+ ions with n=4-6. The propargyl radical is believed to control the synthesis of the first aromatic ring in combustion processes, and it probably plays a key role in the synthesis of large organic molecules and cyclization processes to benzene in cold dark clouds.

Abstract Copyright: © ESO 2021

Journal keyword(s): astrochemistry - line: identification - molecular processes - ISM: molecules - radio lines: ISM

Simbad objects: 2

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2022.09.29-15:48:17

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