Laboratory and Astronomical Identification of the Negative Molecular Ion C
                    <sub>6</sub>
                    H
                    <sup>-</sup>

McCarthy, Michael; Gottlieb, C. A.; Gupta, H. M. Sen; Thaddeus, P.

doi:10.1086/510238

Cited by 441 publications

(363 citation statements)

References 30 publications

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“…C 6 H − and C 8 H − have also been detected in the cold, dense interstellar cloud TMC-1 (McCarthy et al 2006, Brüenken et al 2007, and C 4 H − and C 6 H − in the protostellar source L1527 (Sakai et al 2007, Agúndez et al 2008. Fractional abundance ratios of the anions relative to their neutral parents of up to 0.1 indicate that anions may play a more significant role in interstellar physics and chemistry than previously believed.…”

Section: Introductionmentioning

confidence: 86%

Organic molecular anions in interstellar and circumstellar environments

et al. 2008

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Abstract. The synthesis of organic molecular anions in TMC-1 and IRC+10216 is investigated. Modelled C2 H − , CN − , C3 N − , C5 N − and C7 N − column densities are sufficiently great that these species might be observable in IRC+10216. Density-enhanced shells in the outer envelope of IRC+10216 are found to enhance the C2 H − and CN − column densities by shielding these anions from destruction by UV radiation. From a newly-derived upper column density limit of 6.6×10 10 cm −2 for C2 H − in IRC+10216 we deduce the primary production mechanism for this anion to be C2 H2 + H − −→ C2 H − + H2 . In TMC-1, due to the low radiative electron attachment rates calculated for C2 H − , CN − and CH2 CN − , these species have modelled column densities below the detection threshold. They could, however, be produced in reactions we have not yet considered.

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Section: Introductionmentioning

confidence: 86%

Organic molecular anions in interstellar and circumstellar environments

et al. 2008

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“…The recent detection of C 6 H − in IRC+10216 by McCarthy et al (2006), was predicted implicitly by the calculations of Millar et al (2000) who predicted anion/neutral ratios of between 0.01 and 0.4 based on efficient formation through radiative electron attachment, which occurs when the neutral has six or more atoms, and destruction mainly through photodissociation. Detailed calculations by Millar et al (2007) show that anions as small as C 4 H − should be detectable in IRC+10216.…”

Section: The Photochemical Regionmentioning

confidence: 99%

Chemistry in the circumstellar medium

Millar

2007

Astrophys Space Sci

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The growth of dust grains in the inner regions of late-type stars is shrouded in mystery due to the difficulty of understanding the growth of heterogeneous particles from simple atoms and molecules and the lack of observational data. This article reviews the molecular processes important in circumstellar envelopes and discusses how ALMA might be used to probe the dust formation zone either directly or indirectly.

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“…Additionally, the electron-ion recombination of species such as acetic acid associated with NH 4 ϩ may also yield a product of interest if during this process rearrangement can occur. In addition C 4 H Ϫ has recently been© detected© [30]© and© ion-ion© recombination© could© also contribute to the neutral products (note that this produces less fragmentation than electron-ion recombination). Little is known about the structure and bonding of these associated products beyond what has been investigated here, and further study in both theory and experiment is needed.…”

Section: Discussionmentioning

confidence: 99%

Ion-molecule reactions of several ions with ethylene oxide and propenal in a selected ion flow tube

Jackson

Adams

Babcock

2007

J. Am. Soc. Mass Spectrom.

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The selected ion flow tube (SIFT) technique has been used to investigate the ion-molecule reactions of several ions with the neutral molecules ethylene oxide, CH 2 OCH 2 -c, and propenal, CH 2 CHCHO. Both molecules have been identified in hot-core star forming regions [1, 2]© and have significance to astrochemical models of the interstellar (ISM) and circumstellar medium (CSM). Moreover, the molecules contain functional groups, such as the epoxide group (ethylene oxide) and an aldehyde group, which are part of a conjugated -electron system (propenal) whose reactivities have not been studied in detail in gas-phase ion-molecule reactions. The larger recombination energy ions, Ar ϩ and N 2 ϩ , were reacted with the neutrals to give insight into general fragmentation tendencies. These reactions proceeded via dissociative charge-transfer yielding major fragmentation products of CH 3 ϩ and HCO ϩ for ethylene oxide and CH 2 CH ϩ and HCO ϩ for propenal. The amino acids glycine and alanine are of particular interest to astrobiology, especially if they can be synthesized in the gas phase. In an attempt to synthesize amino acid precursors, ethylene oxide and propenal were reacted with NH n ϩ (n ϭ 1-4) and HCNH ϩ . As might be expected from the proton detachment energies, NH ϩ , NH 2 ϩ , and HCNH ϩ reacted via proton transfer. NH 3 ϩ reacted with each molecule via H-atom abstraction to produce NH 4 ϩ , and NH 4 ϩ reacted via a ternary association. All binary reactions proceeded near the gas kinetic rate. Several associated molecule switching reactions were performed and implications of these reactions to the structures of the association products are discussed Ikeda et al. and Hollis et al. (J Am Soc Mass Spectrom 2007, 18, 445-452)

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Laboratory and Astronomical Identification of the Negative Molecular Ion C ₆ H ^-

Cited by 441 publications

References 30 publications

Organic molecular anions in interstellar and circumstellar environments

Organic molecular anions in interstellar and circumstellar environments

Chemistry in the circumstellar medium

Ion-molecule reactions of several ions with ethylene oxide and propenal in a selected ion flow tube

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Laboratory and Astronomical Identification of the Negative Molecular Ion C 6 H -

Cited by 441 publications

References 30 publications

Organic molecular anions in interstellar and circumstellar environments

Organic molecular anions in interstellar and circumstellar environments

Chemistry in the circumstellar medium

Ion-molecule reactions of several ions with ethylene oxide and propenal in a selected ion flow tube

Contact Info

Product

Resources

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Laboratory and Astronomical Identification of the Negative Molecular Ion C ₆ H ^-