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Hickson KM, Loison JC. Kinetic Study of the Gas-Phase O( 1D) + CH 3OH and O( 1D) + CH 3CN Reactions: Low-Temperature Rate Constants and Atomic Hydrogen Product Yields. J Phys Chem A 2022; 126:3903-3913. [PMID: 35687018 DOI: 10.1021/acs.jpca.2c01946] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Atomic oxygen in its first excited singlet state, O(1D), is an important species in the photochemistry of several planetary atmospheres and has been predicted to be a potentially important reactive species on interstellar ices. Here, we report the results of a kinetic study of the reactions of O(1D) with methanol, CH3OH, and acetonitrile, CH3CN, over the 50-296 K temperature range. A continuous supersonic flow reactor is used to attain these low temperatures coupled with pulsed laser photolysis and pulsed laser-induced fluorescence to generate and monitor O(1D) atoms, respectively. Secondary experiments examining the atomic hydrogen product channels of these reactions are also performed, through laser-induced fluorescence measurements of H(2S) atom formation. On the kinetic side, the rate constants for these reactions are seen to be large (>2 × 10-10 cm3 s-1) and consistent with barrierless reactions, although they display contrasting dependences as a function of temperature. On the product formation side, both reactions are seen to yield non-negligible quantities of atomic hydrogen. For the O(1D) + CH3OH reaction, the derived yields are in good agreement with the conclusions of previous experimental and theoretical works. For the O(1D) + CH3CN reaction, whose H-atom formation channels had not previously been investigated, electronic structure calculations of several new product formation channels are performed to explain the observed H-atom yields. These calculations demonstrate the barrierless and exothermic nature of the relevant exit channels, confirming that atomic hydrogen is also an important product of the O(1D) + CH3CN reaction.
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Affiliation(s)
- Kevin M Hickson
- Université Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
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Hickson KM, Loison JC, Larregaray P, Bonnet L, Wakelam V. An Experimental and Theoretical Investigation of the Gas-Phase C( 3P) + N 2O Reaction. Low Temperature Rate Constants and Astrochemical Implications. J Phys Chem A 2022; 126:940-950. [PMID: 35113561 DOI: 10.1021/acs.jpca.1c10112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction between atomic carbon in its ground electronic state, C(3P), and nitrous oxide, N2O, has been studied below room temperature due to its potential importance for astrochemistry, with both species considered to be present at high abundance levels in a range of interstellar environments. On the experimental side, we measured rate constants for this reaction over the 50-296 K range using a continuous supersonic flow reactor. C(3P) atoms were generated by the pulsed photolysis of carbon tetrabromide at 266 nm and were detected by pulsed laser-induced fluorescence at 115.8 nm. Additional measurements allowing the major product channels to be elucidated were also performed. On the theoretical side, statistical rate theory was used to calculate low temperature rate constants. These calculations employed the results of new electronic structure calculations of the 3A″ potential energy surface of CNNO and provided a basis to extrapolate the measured rate constants to lower temperatures and pressures. The rate constant was found to increase monotonically as the temperature falls (kC(3P)+N2O (296 K) = (3.4 ± 0.3) × 10-11 cm3 s-1), reaching a value of kC(3P)+N2O (50 K) = (7.9 ± 0.8) × 10-11 cm3 s-1 at 50 K. As current astrochemical models do not include the C + N2O reaction, we tested the influence of this process on interstellar N2O and other related species using a gas-grain model of dense interstellar clouds. These simulations predict that N2O abundances decrease significantly at intermediate times (103 - 105 years) when gas-phase C(3P) abundances are high.
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Affiliation(s)
- Kevin M Hickson
- Université Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | | | - Pascal Larregaray
- Université Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | - Laurent Bonnet
- Université Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
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Hickson KM, Bhowmick S, Suleimanov YV, Brandão J, Coelho DV. Experimental and theoretical studies of the gas-phase reactions of O( 1D) with H 2O and D 2O at low temperature. Phys Chem Chem Phys 2021; 23:25797-25806. [PMID: 34761769 DOI: 10.1039/d1cp04614d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here we report the results of an experimental and theoretical study of the gas-phase reactions between O(1D) and H2O and O(1D) and D2O at room temperature and below. On the experimental side, the kinetics of these reactions have been investigated over the 50-127 K range using a continuous flow Laval nozzle apparatus, coupled with pulsed laser photolysis and pulsed laser induced fluorescence for the production and detection of O(1D) atoms respectively. Experiments were also performed at 296 K in the absence of a Laval nozzle. On the theoretical side, the existing full-dimensional ground X 1A potential energy surface for the H2O2 system involved in this process has been reinvestigated and enhanced to provide a better description of the barrierless H-atom abstraction pathway. Based on this enhanced potential energy surface, quasiclassical trajectory calculations and ring polymer molecular dynamics simulations have been performed to obtain low temperature rate constants. The measured and calculated rate constants display similar behaviour above 100 K, showing little or no variation as a function of temperature. Below 100 K, the experimental rate constants increase dramatically, in contrast to the essentially temperature independent theoretical values. The possible origins of the divergence between experiment and theory at low temperatures are discussed.
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Affiliation(s)
- Kevin M Hickson
- Université de Bordeaux, Institut des Sciences Moléculaires, F-33400 Talence, France. .,CNRS, Institut des Sciences Moléculaires, F-33400 Talence, France
| | - Somnath Bhowmick
- Computation-based Science and Technology Research Center, The Cyprus Institute, 20 Konstantinou Kavafi Street, Nicosia 2121, Cyprus.,Climate & Atmosphere Research Centre, The Cyprus Institute, 20 Konstantinou Kavafi Street, Nicosia 2121, Cyprus
| | - Yury V Suleimanov
- Computation-based Science and Technology Research Center, The Cyprus Institute, 20 Konstantinou Kavafi Street, Nicosia 2121, Cyprus
| | - João Brandão
- Departamento de Química e Farmácia - FCT, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Daniela V Coelho
- Departamento de Química e Farmácia - FCT, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
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Hickson KM, Bray C, Loison JC, Dobrijevic M. A kinetic study of the N( 2D) + C 2H 4 reaction at low temperature. Phys Chem Chem Phys 2020; 22:14026-14035. [PMID: 32558865 DOI: 10.1039/d0cp02083d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electronically excited nitrogen atoms N(2D) are important species in the photochemistry of N2 based planetary atmospheres such as Titan. Despite this, few N(2D) reactions have been studied over the appropriate low temperature range. During the present work, rate constants were measured for the N(2D) + ethene (C2H4) reaction using a supersonic flow reactor at temperatures between 50 K and 296 K. Here, a chemical reaction was used to generate N(2D) atoms, which were detected directly by laser induced fluorescence in the vacuum ultraviolet wavelength region. The measured rate constants displayed very little variation as a function of temperature, with substantially larger values than those obtained in previous work. Indeed, considering an average temperature of 170 K for the atmosphere of Titan leads to a rate constant that is almost seven times larger than the currently recommended value. In parallel, electronic structure calculations were performed to provide insight into the reactive process. While earlier theoretical work at a lower level predicted the presence of a barrier for the N(2D) + C2H4 reaction, the present calculations demonstrate that two of the five doublet potential energy surfaces correlating with reagents are likely to be attractive, presenting no barriers for the perpendicular approach of the N atom to the C[double bond, length as m-dash]C bond of ethene. The measured rate constants and new product channels taken from recent dynamical investigations of this process are included in a 1D coupled ion-neutral model of Titan's atmosphere. These simulations indicate that the modeled abundances of numerous nitrogen bearing compounds are noticeably affected by these changes.
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Affiliation(s)
- Kevin M Hickson
- Université de Bordeaux, Institut des Sciences Moléculaires, UMR 5255, F-33400 Talence, France.
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Nuñez-Reyes D, Hickson KM, Larrégaray P, Bonnet L, González-Lezana T, Bhowmick S, Suleimanov YV. Experimental and Theoretical Study of the O( 1D) + HD Reaction. J Phys Chem A 2019; 123:8089-8098. [PMID: 31464440 DOI: 10.1021/acs.jpca.9b06133] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This work addresses the kinetics and dynamics of the gas-phase reaction between O(1D) and HD molecules down to low temperature. Here, measurements were performed by using a supersonic flow (Laval nozzle) reactor coupled with pulsed laser photolysis for O(1D) production and pulsed-laser-induced fluorescence for O(1D) detection to obtain rate constants over the 50-300 K range. Additionally, temperature-dependent branching ratios (OD + H/OH + D) were obtained experimentally by comparison of the H/D atom atom yields with those of a reference reaction. In parallel, theoretical rate constants and branching ratios were calculated by using three different techniques; mean potential phase space theory (MPPST), the statistical quantum mechanical method (SQM), and ring polymer molecular dynamics (RPMD). Although the agreement between experimental and theoretical rate constants is reasonably good, with differences not exceeding 30% over the entire temperature range, the theoretical branching ratios derived by the MPPST and SQM methods are as much as 50% larger than the experimental ones. These results are presented in the context of earlier work, while the possible origins of the discrepancies between experiment and theory are discussed.
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Affiliation(s)
- Dianailys Nuñez-Reyes
- Université de Bordeaux, Institut des Sciences Moléculaires , F-33400 Talence , France.,CNRS, Institut des Sciences Moléculaires , UMR 5255, F-33400 Talence , France
| | - Kevin M Hickson
- Université de Bordeaux, Institut des Sciences Moléculaires , F-33400 Talence , France.,CNRS, Institut des Sciences Moléculaires , UMR 5255, F-33400 Talence , France
| | - Pascal Larrégaray
- Université de Bordeaux, Institut des Sciences Moléculaires , F-33400 Talence , France.,CNRS, Institut des Sciences Moléculaires , UMR 5255, F-33400 Talence , France
| | - Laurent Bonnet
- Université de Bordeaux, Institut des Sciences Moléculaires , F-33400 Talence , France.,CNRS, Institut des Sciences Moléculaires , UMR 5255, F-33400 Talence , France
| | - Tomás González-Lezana
- Instituto de Física Fundamental , CSIC , IFF-CSIC Serrano 123 , 28006 Madrid , Spain
| | - Somnath Bhowmick
- Computation-based Science and Technology Research Center , The Cyprus Institute , 20 Konstantinou Kavafi Street , Nicosia 2121 , Cyprus
| | - Yury V Suleimanov
- Computation-based Science and Technology Research Center , The Cyprus Institute , 20 Konstantinou Kavafi Street , Nicosia 2121 , Cyprus.,Department of Chemical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
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Hickson KM. Low-Temperature Rate Constants and Product-Branching Ratios for the C( 1D) + H 2O Reaction. J Phys Chem A 2019; 123:5206-5213. [PMID: 31198039 DOI: 10.1021/acs.jpca.9b03037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The gas-phase reaction between atomic carbon in its first electronically excited 1D state and water has been studied over the 50-296 K temperature range using a supersonic flow apparatus. C(1D) atoms were produced by pulsed ultraviolet multiphoton dissociation of carbon tetrabromide; a process that also generates ground-state atomic carbon C(3P). The reaction was followed by detecting product H-atoms by pulsed vacuum ultraviolet laser-induced fluorescence. Two types of experiment were performed. First, temperature-dependent rate constants were derived by recording H-atom formation curves at various gas-phase water concentrations at each temperature. Secondly, temperature-dependent H-atom yields were extracted by comparing the H-atom fluorescence intensities generated by the target C(1D) + H2O reaction with those of a reference reaction. The second-order rate constants are large and increase to low temperature, whereas the measured H-atom yields are close to the theoretical maximum value of 2 above 100 K. At 50 K, neither rate constants nor H-atom yields could be derived because of H-atom formation by quantum tunneling in the activated C(3P) + H2O reaction. The present results are discussed in the context of earlier work on the C(1D)/C(3P) + H2O reactions.
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Affiliation(s)
- Kevin M Hickson
- Université de Bordeaux, Institut des Sciences Moléculaires , F-33400 Talence , France.,CNRS, Institut des Sciences Moléculaires , F-33400 Talence , France
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Nuñez-Reyes D, Loison JC, Hickson KM, Dobrijevic M. A low temperature investigation of the N(2D) + CH4, C2H6 and C3H8 reactions. Phys Chem Chem Phys 2019; 21:6574-6581. [DOI: 10.1039/c9cp00798a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Low temperature rate constants for the N(2D) + C2H6, C3H8 reactions are shown to be much smaller than previously thought.
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Affiliation(s)
- Dianailys Nuñez-Reyes
- Université de Bordeaux
- Institut des Sciences Moléculaires
- UMR 5255
- F-33400 Talence
- France
| | | | - Kevin M. Hickson
- Université de Bordeaux
- Institut des Sciences Moléculaires
- UMR 5255
- F-33400 Talence
- France
| | - Michel Dobrijevic
- Laboratoire d'Astrophysique de Bordeaux
- Université de Bordeaux
- CNRS, B18N
- allée Geoffroy Saint-Hilaire
- F-33615 Pessac
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Nuñez-Reyes D, Loison JC, Hickson KM, Dobrijevic M. Rate constants for the N(2D) + C2H2 reaction over the 50–296 K temperature range. Phys Chem Chem Phys 2019; 21:22230-22237. [DOI: 10.1039/c9cp04170b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reactions of metastable atomic nitrogen N(2D) are important processes in the gas-phase chemistry of several planetary atmospheres.
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Affiliation(s)
- Dianailys Nuñez-Reyes
- Université de Bordeaux
- Institut des Sciences Moléculaires
- UMR 5255
- F-33400 Talence
- France
| | | | - Kevin M. Hickson
- Université de Bordeaux
- Institut des Sciences Moléculaires
- UMR 5255
- F-33400 Talence
- France
| | - Michel Dobrijevic
- Laboratoire d'Astrophysique de Bordeaux
- Université de Bordeaux
- CNRS
- F-33615 Pessac
- France
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