Reaction of C2H with NO and O2 studied by TR-FTIR emission spectroscopy

Su, Hongmei; Yang, Jixin; Ye, Ding; Feng, Wenhui; Kong, Fanzuo

doi:10.1016/s0009-2614(00)00775-2

Cited by 23 publications

(22 citation statements)

References 30 publications

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“…Moreover our current astrochemical model leads to an O2 abundance higher than observed for dense molecular clouds (Pagani et al 2003), inducing an overestimation of HCCO production through the CCH + O2 reaction. Instead of including HCCO production from the CCH + O2 reaction in our standard model (the CCH + O2 reaction producing only H, HCO, CO and CO2 Su et al 2000), we performed a test run to see the effect of its inclusion. When the CCH + O2 → HCCO + O reaction is included, an increase of the HCCO abundance is observed in the 3-5×10 5 yr range (reaching few 10 −11 of H2) corresponding to the peak of the O2 abundance profile.…”

Section: Predicted Abundancesmentioning

confidence: 99%

A proposed chemical scheme for HCCO formation in cold dense clouds

Wakelam

Loison

Hickson

et al. 2015

Monthly Notices of the Royal Astronomical Society: Letters

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The ketenyl radical (HCCO) has recently been discovered in two cold dense clouds with a non-negligible abundance of a few 10 −11 (compared to H 2 ) (Agúndez et al. 2015). Until now, no chemical network has been able to reproduce this observation. We propose here a chemical scheme that can reproduce HCCO abundances together with HCO, H 2 CCO and CH 3 CHO in the dark clouds Lupus-1A and L486. The main formation pathway for HCCO is the OH + CCH → HCCO + H reaction as suggested by Agúndez et al. (2015) but with a much larger rate coefficient than used in current models. Since this reaction has never been studied experimentally or theoretically, this larger value is based on a comparison with other similar systems.

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Section: Predicted Abundancesmentioning

confidence: 99%

A proposed chemical scheme for HCCO formation in cold dense clouds

Wakelam

Loison

Hickson

et al. 2015

Monthly Notices of the Royal Astronomical Society: Letters

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“…The intensity of the laser beam was about 800). A nonlinear least-square spectral simulation [21] was performed for the emission of CO at 6 fls (Fig. The spectral resolution was set at 16 cm-I .…”

Section: Methodsmentioning

confidence: 99%

Reaction of CH radical with O2 by time-resolved FTIR spectroscopy

Ren

Kong

2003

Chin. Sci. Bull.

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AbstractsThe reaction of CH radical with O 2 has been experimentally investigated by time-resolved Fourier transform IR emission spectroscopy. CH radicals were generated by multi-photon UV laser photolysis of bromoform (CHBr3) in gaseous phase. Highly vibrationally excited product CO (v =1-12) with a near Boltzmann distribution was observed after the reaction. The vibrational temperature of CO is estimated as high as 14400±1400 K and the averaged vibrational energy is about 25.8 kcal·mor 1• The emission intensity of CO is not sensitive to the quenching gas, which indicates that there is no early barrier in the reaction of CH+0 2 • However, the theoretically predicted product CO 2 has not been found in the experiment.

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“…The small entrance barrier for CO 2 + CH is in good agreement with previous theoretical 78 and kinetic studies 79 that report a small activation energy for this reaction. Experimental studies 27,28 have reported relative CO 2 /CO yields in excess of 1:4, which would be unexpected given the relative barrier heights for TS3 (0.1 kcal mol −1 ) and TS4 (38.3 kcal mol −1 ). Furthermore, many experimental studies 24,25,38−40 have observed methlyidene in excited electronic states such as 2 Δ.…”

Section: We Can Estimate the Branching Ratio Of The Decomposition Rea...mentioning

confidence: 98%

“…As one of the most abundant polyatomic molecules in the universe, • C 2 H appears in interstellar clouds, − carbon-rich stars, , and low temperature planetary atmospheres such as that of Jupiter and Titan. − In combustion environments, the ethynyl radical is formed during the oxidation of various alkynes . The most notable reaction involving the ethynyl radical is the combustion of acetylene/O 2 flames, where the ethynyl radical is readily formed through an abstraction of a hydrogen atom from C 2 H 2 . , The ethynyl radical can subsequently react with oxygen to form the variety of thermodynamically favorable products − identified below: Of these potential products, HCCO, CH, CO 2 , and CO have been directly observed in the laboratory. − Kinetic studies for the reaction • C 2 H + O 2 have reported large rate constants with slight negative temperature dependences, − suggesting the formation of the initial complex of this reaction has a negligible barrier. Furthermore, experimental studies have shown that the rate constant for this reaction is pressure independent, , which implies that the initially formed complex decomposes rapidly and that redissociation into the reactants is prohibitive.…”

Section: Introductionmentioning

confidence: 99%

“…The highly exothermic nature of these reactions often leaves the products in excited electronic or vibrational states. , The most noticeable electronically excited product is CH (A 2 Δ). The electronic relaxation of CH (A 2 Δ → X 2 Π) is responsible for the emission of bright blue light (435 nm) that is produced in oxo-acetylene flames.…”

Section: Introductionmentioning

confidence: 99%

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Mechanisms of the Ethynyl Radical Reaction with Molecular Oxygen

et al. 2018

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The ethynyl radical, •C2H, is a key intermediate in the combustion of various alkynes. Once produced, the ethynyl radical will rapidly react with molecular oxygen to produce a variety of products. This research presents the first comprehensive high level theoretical study of the reaction of the •C2H (2Σ+) radical with molecular oxygen (3Σg –). Correlation methods as complete as CCSDT(Q) were used; basis sets as large as cc-pV6Z were adopted. Focal point analysis was employed to approach relative energies within the bounds of chemical accuracy (≤1 kcal mol–1). Two dominate reaction pathways from the ethynyl peroxy radical include oxygen–oxygen cleavage from the ethynyl peroxy radical that is initially formed to produce HCCO (2A″) and O (3P) and an isomerization of the ethynyl peroxy radical to eventually yield HCO (2A′) and CO (1Σ+). The branching ratio between these two competitive reaction pathways was determined to be 1:1 at 298 K. Minor reaction pathways leading to the production of CO2 (1Σg +) and CH (2Π, 4Σ–, 2Δ) were also characterized. The absence of CCO (3Σ–) and OH (2Π) was explained in terms competition with more accessible reaction pathways.

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Reaction of C2H with NO and O2 studied by TR-FTIR emission spectroscopy

Cited by 23 publications

References 30 publications

A proposed chemical scheme for HCCO formation in cold dense clouds

A proposed chemical scheme for HCCO formation in cold dense clouds

Reaction of CH radical with O2 by time-resolved FTIR spectroscopy

Mechanisms of the Ethynyl Radical Reaction with Molecular Oxygen

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