Kinetic Study of the Gas-Phase Reaction between Atomic Carbon and Acetone: Low-Temperature Rate Constants and Hydrogen Atom Product Yields

Hickson, Kevin M.; Loison, Jean-Christophe; Wakelam, Valentine

doi:10.1021/acsearthspacechem.3c00193

Cited by 3 publications

(1 citation statement)

References 69 publications

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“…If we extrapolate the fit down to a typical dense interstellar cloud temperature of 10 K, a value of k C+CH 3 OCH 3 (10 K) = 4.01 × 10 –10 cm 3 s –1 is obtained. While qualitatively similar temperature dependences were observed in earlier studies of the related C + CH 3 OH and C + NH 3 reactions, the reactions of atomic carbon with acetonitrile, CH 3 CN, and acetone, CH 3 COCH 3 , display contrasting behavior, being rapid over the entire temperature range between 50 and 296 K, with little or no temperature dependence. This difference appears to be due the nature of the TS separating the initial complex formed by the reagents from the more stable adducts over the respective potential energy surfaces.…”

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confidence: 79%

A Low-Temperature Kinetic Study of the C(³P) + CH₃OCH₃ Reaction: Rate Constants, H Atom Product Yields, and Astrochemical Implications

Hickson,

Loison,

Wakelam

2024

ACS Earth Space Chem.

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Atomic carbon in its ground electronic state, C( 3 P), is expected to be present at high abundances during the evolution of dense molecular clouds. Consequently, its reactions with other interstellar species could have a strong influence on the chemical composition of these regions. Here, we report the results of an investigation of the reaction between C( 3 P) and dimethyl ether, CH 3 OCH 3 , which was recently detected in dark cloud TMC-1. Experiments were performed to study the kinetics of this reaction using a continuous supersonic flow reactor employing pulsed laser photolysis and pulsed laser-induced fluorescence for atomic radical generation and detection, respectively. Rate constants for this process were measured between 50 and 296 K, while additional measurements of the product atomic hydrogen yields were also performed over the 75−296 K range. To better understand the experimental results, statistical rate theory was used to calculate rate constants over the same temperature range and to provide insight on the major product channels. These simulations, based on quantum chemical calculations of the ground triplet state of the C 3 H 6 O molecule, allowed us to obtain the most important features of the underlying potential energy surface. The measured rate constant increases as the temperature falls, reaching a value of k C+CHd 3 OCHd 3 = 7.5 × 10 −11 cm 3 s −1 at 50 K, while the low measured H atom yields support the theoretical prediction that the major reaction products are CH 3 + CH 3 + CO. The effects of this reaction on the abundances of interstellar CH 3 OCH 3 and related species were tested using a gas-grain model of dense interstellar clouds, employing an expression for the rate constant, k(T) = α(T/300) β , with α = 1.27 × 10 −11 and β = −1.01. These simulations predict that the C( 3 P) + CH 3 OCH 3 reaction decreases gas-phase CH 3 OCH 3 abundances by more than an order of magnitude at early and intermediate cloud ages.

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Section: Resultssupporting

confidence: 79%

A Low-Temperature Kinetic Study of the C(³P) + CH₃OCH₃ Reaction: Rate Constants, H Atom Product Yields, and Astrochemical Implications

Hickson,

Loison,

Wakelam

2024

ACS Earth Space Chem.

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Kinetic Study of the Reactions of Ground State Atomic Carbon and Oxygen with Nitrogen Dioxide over the 50–296 K Temperature Range

Hickson,

Loison

2024

J. Phys. Chem. A

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The kinetics of the reactions of nitrogen dioxide, NO 2 , with atomic oxygen and atomic carbon in their ground triplet states ( 3 P) have been studied at room temperature and below using a supersonic flow (Laval nozzle) reactor. O( 3 P) and C( 3 P) atoms (hereafter O and C respectively) were created in situ by the pulsed laser photolysis of the precursor molecules NO 2 at 355 nm and CBr 4 at 266 nm, respectively. While the progress of the O + NO 2 reaction was followed by detecting O atoms by a chemiluminescent tracer method, progress of the C + NO 2 reaction was followed by detecting C atoms directly by vacuum ultraviolet laser-induced fluorescence at 116 nm. The measured rate constants for the O + NO 2 reaction are found to be in excellent agreement with earlier work at higher temperatures and extend the available kinetic data for this process down to 50 K. The present work represents the first kinetics study of the C + NO 2 reaction. Although both reactions display rate constants that increase as the temperature falls, a more substantial rate increase is observed for the O + NO 2 reaction. The effects of these reactions on the simulated abundances of interstellar NO 2 and related compounds were tested using a gas−grain model of the dense interstellar medium, employing expressions for the rate constants of the form, k(T) = α(T/300) β , with α = 1 × 10 −11 cm 3 s −1 and β = −0.65 for the O + NO 2 reaction and α = 2 × 10 −10 cm 3 s −1 and β = −0.11 for the C + NO 2 reaction. Although these simulations predict that gas-phase NO 2 abundances are low in dense interstellar clouds, NO 2 abundances on interstellar dust grains are predicted to reach reasonably high levels, indicating the potential for detection of this species in warmer regions.

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Absolute rate coefficient measurements of the reactions of vibrationally cold HD+ and H3+ ions with neutral C atoms

Grussie,

Berger,

Grieser

et al. 2024

Phys. Rev. A

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Ion-neutral reactions are driving the formation of small molecules in the gas phase of interstellar clouds, where hydrogen molecules and their ions are by far the most important collision partners for any species in the astrochemical network. Here we present absolute rate coefficient measurements for the reactions HD++C→CH+/CD++D/H and H3++C→CH+/CH2++H2/H obtained using a recently commissioned ion-neutral collision setup at the Cryogenic Storage Ring. Our measurements with vibrationally cold ions result in significantly higher rate coefficients when compared with previous studies using internally excited ions, bringing them in better agreement with classical capture theories. Moreover, we have performed detailed quasiclassical trajectory (QCT) calculations for the HD++C reaction, using new potential energy surfaces. Our experimental results and the QCT calculations show very good agreement for the absolute cross section of the reactions, as well as for the isotope effect. These results have great potential relevance for the chemistry of the interstellar medium and the onset of organic chemistry in space. Published by the American Physical Society 2024

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Kinetic Study of the Gas-Phase Reaction between Atomic Carbon and Acetone: Low-Temperature Rate Constants and Hydrogen Atom Product Yields

Cited by 3 publications

References 69 publications

A Low-Temperature Kinetic Study of the C(³P) + CH₃OCH₃ Reaction: Rate Constants, H Atom Product Yields, and Astrochemical Implications

A Low-Temperature Kinetic Study of the C(³P) + CH₃OCH₃ Reaction: Rate Constants, H Atom Product Yields, and Astrochemical Implications

Kinetic Study of the Reactions of Ground State Atomic Carbon and Oxygen with Nitrogen Dioxide over the 50–296 K Temperature Range

Absolute rate coefficient measurements of the reactions of vibrationally cold HD+ and H3+ ions with neutral C atoms

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Kinetic Study of the Gas-Phase Reaction between Atomic Carbon and Acetone: Low-Temperature Rate Constants and Hydrogen Atom Product Yields

Cited by 3 publications

References 69 publications

A Low-Temperature Kinetic Study of the C(3P) + CH3OCH3 Reaction: Rate Constants, H Atom Product Yields, and Astrochemical Implications

A Low-Temperature Kinetic Study of the C(3P) + CH3OCH3 Reaction: Rate Constants, H Atom Product Yields, and Astrochemical Implications

Kinetic Study of the Reactions of Ground State Atomic Carbon and Oxygen with Nitrogen Dioxide over the 50–296 K Temperature Range

Absolute rate coefficient measurements of the reactions of vibrationally cold HD+ and H3+ ions with neutral C atoms

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A Low-Temperature Kinetic Study of the C(³P) + CH₃OCH₃ Reaction: Rate Constants, H Atom Product Yields, and Astrochemical Implications

A Low-Temperature Kinetic Study of the C(³P) + CH₃OCH₃ Reaction: Rate Constants, H Atom Product Yields, and Astrochemical Implications