Mechanism and Rate of the Reaction of Cyanomethyl Radicals with Oxygen Atoms in the Gas Phase

Hoyermann, K.; Seeba, Johann

doi:10.1524/zpch.1995.188.part_1_2.215

Cited by 14 publications

(15 citation statements)

References 13 publications

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“…HCNO is likely produced but is not in our model. Rate constant deduced from (Hoyermann & Seeba 1995), branching ratio estimated using exothermicities. (Mitchell et al 1986).…”

Section: + Hncmentioning

confidence: 99%

The interstellar gas-phase chemistry of HCN and HNC

Loison¹,

Wakelam²,

Hickson³

2014

Monthly Notices of the Royal Astronomical Society

107

109

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+ CH 2 reaction and two new reactions: H + CCN and C + HNC. We test the effect of the new rate constants and branching ratios on the predictions of gas-grain chemical models for dark cloud conditions. The rapid C + HNC reaction keeps the HCN/HNC ratio significantly above one as long as the carbon atom abundance remains high. However, the reaction of HCN with H 3 + followed by DR of HCNH + acts to isomerize HCN into HNC when carbon atoms and CO are depleted leading to a HCN/HNC ratio close to or slightly greater than 1. This agrees well with observations in TMC-1 and L134N taking into consideration the overestimation of HNC abundances through the use of the same rotational excitation rate constants for HNC as for HCN in many radiative transfer models.

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“…HCNO is likely produced but is not in our model. Rate constant deduced from (Hoyermann & Seeba 1995), branching ratio estimated using exothermicities. (Mitchell et al 1986).…”

Section: + Hncmentioning

confidence: 99%

The interstellar gas-phase chemistry of HCN and HNC

Loison¹,

Wakelam²,

Hickson³

2014

Monthly Notices of the Royal Astronomical Society

107

109

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“…Only transitions to neutral states with even quanta in the ν 5 mode can originate from the ground vibrational state of the anion: 5 2 0 (peak G) and 5 4 0 (peak L). Allowed transitions to neutral states with odd ν 5 quanta must originate from the anion v 5 = 1 state: 5 1 1 (peak C ) and 5 3 1 (peak J ). The hot band nature of the odd-quanta states is made clear by the 5 K spectrum shown in black in Fig.…”

Section: A Vibrational Assignments For Ch 2 Cnmentioning

confidence: 99%

“…The cyanomethyl radical, CH 2 CN, is important astrochemically as an open-shell carbon-containing species. 1,2 It is also an intermediate in hydrocarbon combustion, 3 and is involved in thermal decomposition 4 and atmospheric reactions 5,6 of acetonitrile. The CH 2 CN − anion has been a benchmark system for ion thermochemistry studies, 7,8 and the transition from its electronic ground state to its excited dipole bound state is a plausible candidate for the 803.79 nm diffuse interstellar band (DIB).…”

Section: Introductionmentioning

confidence: 99%

Rovibronic structure in slow photoelectron velocity-map imaging spectroscopy of CH2CN− and CD2CN−

Weichman

Kim

Neumark

2014

The Journal of Chemical Physics

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We report high-resolution anion photoelectron spectra of the cryogenically cooled cyanomethide anion, CH2CN(-), and its isotopologue, CD2CN(-), using slow photoelectron velocity-map imaging (SEVI) spectroscopy. Electron affinities of 12 468(2) cm(-1) for CH2CN and 12 402(2) cm(-1) for CD2CN are obtained, demonstrating greater precision than previous experiments. New vibrational structure is resolved for both neutral species, especially activity of the ν5 hydrogen umbrella modes. The ν6 out-of-plane bending mode fundamental frequency is measured for the first time in both systems and found to be 420(10) cm(-1) for CH2CN and 389(8) cm(-1) for CD2CN. Some rotational structure is resolved, allowing for accurate extraction of vibrational frequencies. Temperature-dependent SEVI spectra show marked effects ascribed to controlled population of low-lying anion vibrational levels. We directly measure the inversion splitting between the first two vibrational levels of the anion ν5 umbrella mode in both species, finding a splitting of 130(20) cm(-1) for CH2CN(-) and 81(20) cm(-1) for CD2CN(-). Franck-Condon forbidden activity is observed and attributed to mode-specific vibrational autodetachment from the CH2CN(-) and CD2CN(-) dipole bound excited states. We also refine the binding energy of the anion dipole bound states to 39 and 42 cm(-1), respectively, for CH2CN(-) and CD2CN(-).

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“…Hence, we conclude that enhanced O( 3 P J ) removal is occurring via its reaction with one or more radical products of reaction (2). The radicals CH 3 , CH 2 CN, CH 2 , CH 2 OH, and CH 3 O are possible products of reaction (2) that react at near-gas-kinetic rates with O( 3 P J ); [72][73][74] none of these radicals can be generated via reaction (1).…”

Section: O(mentioning

confidence: 81%

Kinetic and Mechanistic study of the Reactions of O(¹D₂) with HCN and CH₃CN

2010

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A laser flash photolysis-resonance fluorescence (LFP-RF) technique is employed to investigate the kinetics and mechanism of the reactions of O((1)D(2)) with HCN [reaction (1)] and CH(3)CN [reaction (2)] as a function of temperature over the range 193-430 K. The experiments involve time-resolved RF detection of O((3)P(J)) or H((2)S(1/2)) following LFP of O(3)/X/He mixtures (X=HCN or CH(3)CN), some of which also contain N(2), H(2), and/or NO(2). Measured rate coefficients for total removal of O((1)D(2)) by HCN and CH(3)CN are well-described by the following Arrhenius expressions (units are 10(-10) cm(3) molecule(-1) s(-1)): k(1)(T)=1.08exp(+105/T) and k(2)(T)=2.54exp(-24/T). Temperature-dependent product yields of O((3)P(J)), k(1a)/k(1) and k(2a)/k(2) are well-described by the following Arrhenius-type expressions: k(1a)/k(1)=0.150exp(+200/T) and k(2a)/k(2)=0.0269 exp(+137/T). The H((2)S(1/2)) yield from reaction (2) is found to be 0.16±0.03 independent of temperature (200-423 K). Large 298 K yields of H((2)S(1/2)), 0.68±0.12 produced per O((1)D(2)) destroyed by HCN, are observed for reaction (1). However, observed kinetics suggest that only about half of detected H((2)S(1/2)) is generated as a primary product of the O((1)D(2))+HCN reaction, with the remainder generated via a fast secondary reaction. The implications of the reported kinetic and mechanistic results for understanding the atmospheric chemistry of HCN and CH(3)CN are discussed.

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Mechanism and Rate of the Reaction of Cyanomethyl Radicals with Oxygen Atoms in the Gas Phase

Cited by 14 publications

References 13 publications

The interstellar gas-phase chemistry of HCN and HNC

The interstellar gas-phase chemistry of HCN and HNC

Rovibronic structure in slow photoelectron velocity-map imaging spectroscopy of CH2CN− and CD2CN−

Kinetic and Mechanistic study of the Reactions of O(¹D₂) with HCN and CH₃CN

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Mechanism and Rate of the Reaction of Cyanomethyl Radicals with Oxygen Atoms in the Gas Phase

Cited by 14 publications

References 13 publications

The interstellar gas-phase chemistry of HCN and HNC

The interstellar gas-phase chemistry of HCN and HNC

Rovibronic structure in slow photoelectron velocity-map imaging spectroscopy of CH2CN− and CD2CN−

Kinetic and Mechanistic study of the Reactions of O(1D2) with HCN and CH3CN

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Kinetic and Mechanistic study of the Reactions of O(¹D₂) with HCN and CH₃CN