Laboratory and Astronomical Detection of the Negative Molecular Ion C<sub>3</sub>N<sup>−</sup>

Thaddeus, P.; Gottlieb, C. A.; Gupta, H. M. Sen; Brünken, Sandra; McCarthy, Michael; Agúndez, M.; Guèlin, M.; Cernicharo, J.

doi:10.1086/528947

Cited by 238 publications

(200 citation statements)

References 33 publications

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“…Thus, CN − appears to be confined to the same outer envelope of IRC +10216 as are other molecular anions observed in this source (e.g. Cernicharo et al 2007;Thaddeus et al 2008;Cernicharo et al 2008). A column density of 5 × 10 12 cm −2 and a rotation temperature of 16 K were derived from a rotational diagram constructed with the velocity integrated intensities of the J = 2−1 and 3−2 lines given in Table 1, based on the assumption of a uniform source with a radius of 20 , which is typical of molecules distributed in the outer shell.…”

Section: Observations and Identification Of Cn −mentioning

confidence: 65%

“…The molecular anions detected so far in the interstellar and circumstellar gas are all fairly heavy linear carbon chains consisting of three or more carbon atoms, and with neutral counterparts with large electron affinities: C 4 H − , C 6 H − , C 8 H − , C 3 N − , and C 5 N − (McCarthy et al 2006;Cernicharo et al 2007;Brünken et al 2007a;Remijan et al 2007;Thaddeus et al 2008;Cernicharo et al 2008). The abundance of these anions relative to the neutral counterparts increases with both size and the electron affinity of the neutral molecule, as expected for formation by radiative electron attachment (Herbst & Osamura 2008).…”

Section: Introductionmentioning

confidence: 99%

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Astronomical identification of CN^-, the smallest observed molecular anion

Agúndez¹,

Cernicharo

Guèlin³

et al. 2010

A&A

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We present the first astronomical detection of a diatomic negative ion, the cyanide anion CN − , and quantum mechanical calculations of the excitation of this anion by means of collisions with para-H 2 . The anion CN − is identified by observing the J = 2−1 and J = 3−2 rotational transitions in the C-star envelope IRC +10216 with the IRAM 30-m telescope. The U-shaped line profiles indicate that CN − , like the large anion C 6 H − , is formed in the outer regions of the envelope. Chemical and excitation model calculations suggest that this species forms from the reaction of large carbon anions with N atoms, rather than from the radiative attachment of an electron to CN, as is the case for large molecular anions. The unexpectedly high abundance derived for CN − , 0.25% relative to CN, indicates that its detection in other astronomical sources is likely. A parallel search for the small anion C 2 H − remains inconclusive, despite the previous tentative identification of the J = 1−0 rotational transition. The abundance of C 2 H − in IRC +10216 is found to be vanishingly small, <0.0014% relative to C 2 H.

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Section: Observations and Identification Of Cn −mentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Astronomical identification of CN^-, the smallest observed molecular anion

Agúndez¹,

Cernicharo

Guèlin³

et al. 2010

A&A

Self Cite

227

179

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“…[12][13][14][15][16][17][18] These anions are all closed-shell with AEAs >3.5 eV, are highly conjugated, and have (valance-localized) π*-resonances. The most commonly speculated mechanism for their formation is through capture of a very low energy electron (tens of meV) into a highly diffuse dipole-bound state by virtue of a very large capture cross-section.…”

Section: Role Of Non-adiabatic Dynamics In Astrochemistrymentioning

confidence: 99%

“…For example, they form as products in combustion and anthropogenic pollution, 1 they are used in new generation semiconductors and microelectronics, 2,3 and they have been postulated to be present in astrochemical environments. 4,5 In astrochemistry, anions are recognised as important chemical species, [6][7][8][9][10][11] and have been identified as small polyynes such as C 4 H -and C 6 H -, [12][13][14][15][16][17][18] and are commonly postulated to be present as PAHs. However, the detailed formation mechanism of astrochemical anions is unclear.…”

Section: Introductionmentioning

confidence: 99%

Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

Bull

West

Verlet

2015

Phys. Chem. Chem. Phys.

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Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuumJames N. Bull a , Christopher W. West a and Jan R. R. Verlet a † Photoelectron velocity-map imaging and electronic structure calculations have been used to study the temporary anion (resonance) dynamics of the closed-shell site-specific deprotonated tetracene anion (C18H11 -) in the hv = 3.26 eV (380 nm) to 4.13 eV (300 nm) range. In accord with a recent frequency-, angle-, and time-resolved photoelectron imaging study on a related but open-shell polyaromatic radical anion (Chem. Sci., 2015, 6, 1578-1589, population of π*-resonances situated in the detachment continuum efficiently recover the ground electronic state of the anion through ultrafast non-adiabatic dynamics, followed by characteristic statistical electron loss (thermionic emission). The combined electron yield of direct photodetachment and autodetachment from the optically-accessed resonances in C18H11 -is several orders of magnitude smaller than thermionic emission from the ground electronic electronic state in the photon energy range studied. This result implies a resiliance to prompt photoejection from UV radiation, and the ability of neutral PAH-like species to capture a free electron and form a long-lived molecular anion that ultimately decays by thermionic emission on a millisecond timescale. The attachment mechanism applies to polyaromatic species that cannot support dipole-bound states, and may provide an additional route to forming anions in astrochemical environments. IntroductionPolyaromatic hydrocarbon (PAH) molecules are found across a diverse range of chemical environments. For example, they form as products in combustion and anthropogenic pollution, 1 they are used in new generation semiconductors and microelectronics, 2,3 and they have been postulated to be present in astrochemical environments. 4,5 In astrochemistry, anions are recognised as important chemical species, [6][7][8][9][10][11] and have been identified as small polyynes such as C 4 H -and C 6 H -, [12][13][14][15][16][17][18] and are commonly postulated to be present as PAHs. However, the detailed formation mechanism of astrochemical anions is unclear. It is commonly postulated that stable anions may be formed via electric dipole-bound doorway states; 19,20 however, most neutral PAH molecules do not have a sufficient dipole moment to support such a mechanism.Most molecules,...

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“…Then in December 2006, McCarthy and co-workers reported the Laboratory and Astronomical Identification of the Negative Molecular Ion C 6 H − (McCarthy et al 2006). A total of six anions have now been detected including three hydrogenated carbon chain anions, C 4 H − , C 6 H − , C 8 H − , and three cyano anions, CN − , C 3 N − , C 5 N − (McCarthy et al 2006;Brünken et al 2007;Cernicharo et al 2007Cernicharo et al , 2008Remijan et al 2007;Thaddeus et al 2007;Agúndez et al 2010). These negative ions represent a large fraction of recently detected chemical species, and certainly many more are awaiting discovery.…”

Section: Introductionmentioning

confidence: 99%

Anions in Space and in the Laboratory

Bierbaum¹

2011

Proc. IAU

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Abstract. The astronomical detection of molecular anions has prompted our study of their chemical reactions with atomic species that are abundant in the interstellar medium. We have recently explored the chemistry of a variety of Cx Ny − anions with hydrogen atoms and determined their reaction rate constants and products using the flowing afterglow-selected ion flow tube technique. Computational studies allow characterization of the structures of reactants and products, as well as the energetics along the reaction pathway. For anions containing one or two nitrogen atoms, reactions with hydrogen atoms are facile, and proceed primarily by associative detachment. In contrast, anions containing three nitrogen atoms are unreactive with hydrogen atoms due to reaction barriers and unfavorable thermodynamics.

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Laboratory and Astronomical Detection of the Negative Molecular Ion C₃N⁻

Cited by 238 publications

References 33 publications

Astronomical identification of CN^-, the smallest observed molecular anion

Astronomical identification of CN^-, the smallest observed molecular anion

Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

Anions in Space and in the Laboratory

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Laboratory and Astronomical Detection of the Negative Molecular Ion C3N−

Cited by 238 publications

References 33 publications

Astronomical identification of CN-, the smallest observed molecular anion

Astronomical identification of CN-, the smallest observed molecular anion

Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

Anions in Space and in the Laboratory

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Laboratory and Astronomical Detection of the Negative Molecular Ion C₃N⁻

Astronomical identification of CN^-, the smallest observed molecular anion

Astronomical identification of CN^-, the smallest observed molecular anion