Discovery of the acetyl cation, CH3CO+, in space and in the laboratory

Abstract

Using the Yebes 40m and IRAM 30m radiotelescopes, we detected two series of harmonically related lines in space that can be fitted to a symmetric rotor. The lines have been seen towards the cold dense cores TMC-1, L483, L1527, and L1544. High level of theory ab initio calculations indicate that the best possible candidate is the acetyl cation, CH3CO+, which is the most stable product resulting from the protonation of ketene. We have produced this species in the laboratory and observed its rotational transitions Ju = 10 up to Ju = 27. Hence, we report the discovery of CH3CO+ in space based on our observations, theoretical calculations, and laboratory experiments. The derived rotational and distortion constants allow us to predict the spectrum of CH3CO+ with high accuracy up to 500 GHz. We derive an abundance ratio N(H2CCO)/N(CH3CO+) = 44. The high abundance of the protonated form of H2CCO is due to the high proton affinity of the neutral species. The other isomer, H2CCOH+, is found to be 178.9 kJ/mol above CH3CO+. The observed intensity ratio between the K=0 and K=1 lines, 2.2, strongly suggests that the A and E symmetry states have suffered interconversion processes due to collisions with H and/or H2, or during their formation through the reaction of H3+ with H2CCO.

Accepted for publication in A&A Letters

References in corpus (15)

• The 2014 KIDA network for interstellar chemistry
• The Spatial Distribution of Complex Organic Molecules in the L1544 Pre-stellar Core
• Discovery of Interstellar Propylene (CH_2CHCH_3): Missing Links in Interstellar Gas-Phase Chemistry
• Discovery of Fulminic Acid, HCNO, in Dark Clouds
• Yebes 40 m radio telescope and the broad band NANOCOSMOS receivers at 7 mm and 3 mm for line surveys
• Discovery of HC4NC in TMC-1: A study of the isomers of HC3N, HC5N, and HC7N
• Discovery of HC3O+ in space: The chemistry of O-bearing species in TMC-1
• Space and laboratory discovery of HC3S+
• Interstellar nitrile anions: Detection of C3N- and C5N- in TMC-1
• Tentative detection of HC5NH+ in TMC-1
• Detection of Interstellar HC${}_4$NC and an Investigation of Isocyanopolyyne Chemistry under TMC-1 Conditions
• A study of C4H3N isomers in TMC-1: line by line detection of HCCCH2CN
• Detection of Interstellar HC${}_5$O in TMC-1 with the Green Bank Telescope
• Deep K-band observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, non-detection of HC11N, and a search for new organic molecules
• A sensitive 3 mm line survey of L483: a broad view of the chemical composition of a core around a Class 0 object

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