The vibrational relaxation and pyrolysis of shock heated nitrous oxide

Dove, John E.; Nip, Wing S.; Teitelbaum, Heshel

doi:10.1016/s0082-0784(75)80357-2

Cited by 26 publications

(31 citation statements)

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“…The thermal decomposition and reactions of N 2 O have been the subject of numerous old [1,2] and recent experimental [3][4][5][6][7][8][9] and theoretical [10] studies, as seen in the reviews by Hanson and Salimian [11], Tsang and Herron [12], and more recently, Dean and Bozzelli [13] and Baulch et al [14]. These early studies established that the thermal N 2 O decomposition reaction proceeds via a spin-forbidden, nonadiabatic pathway to form O( 3 P) atoms in preference to the spin-allowed pathway to form O( 1 D) atoms: Consequently, the experimental activation energy of the decomposition reaction was found very much higher than the N 2 -O( 3 P) bond energy.…”

Section: Introductionmentioning

confidence: 99%

A study of N₂O decomposition rate constant at high temperature: Application to the reduction of nitrous oxide by hydrogen

Javoy

Mével

Paillard

2009

Int J of Chemical Kinetics

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Atomic resonance absorption spectroscopy has been used to investigate the thermal decomposition of N 2 O by monitoring the formation of O atoms behind reflected shock waves in the temperature range 1490-2490 K and at total pressures from 58 to 347 kPa, by using the mixtures of N 2 O highly diluted in Ar. For the chosen experimental conditions, the rate coefficient k 1,0 for the reaction N 2 O + Ar → N 2 + O + Ar had the greatest effect on the O atom concentration increase, so this reaction rate constant could be deduced by comparison between experiment and computed simulation. In the actual temperature range, we found k 1,0 (cm 3 mol −1 s −1 ) = 7.2 × 10 14 exp(−28878/T (K )), with an overall uncertainty evaluated to be less than 20%, by considering all the parameters, which contributed to uncertainties in the rate constant determination. The possible absorption at the O triplet emission line of N 2 O has been investigated. The absorption cross section of N 2 O at the O line has been estimated and taken into account for the determination of k 1,0 at high concentrations of N 2 O and at temperatures lower than 1850 K. The effect of the presence of impurities like H 2 O on rate constant determination has been examined and was found to be negligible. The choice of the rate coefficient for the consumption of O atoms by reaction with N 2 O and that of the high-pressure limiting rate coefficients k 1,∞ were also discussed. The rate constant reported in the present study was compared with the literature values and was found to be overall higher than those determined experimentally by other teams in the last decade. Finally, the effect of the modified constant value on reaction rate of diluted Ar-N 2 O mixtures and H 2 -N 2 O-Ar systems was investigated. In the temperature range 1500-2500 K, the use of the rate constant deduced from this study has led to a better prediction of N 2 O decomposition and N 2 O reduction by H 2 than with lower rate constants proposed in the literature.

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Section: Introductionmentioning

confidence: 99%

A study of N₂O decomposition rate constant at high temperature: Application to the reduction of nitrous oxide by hydrogen

Javoy

Mével

Paillard

2009

Int J of Chemical Kinetics

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“…[1][2][3][4][5] Our interest in the subject was prompted by studies of ozone whose formation and isotopic effects have been of much recent interest. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] In general, the formation of a molecule AB is described by A + B AB ‫ء‬ , ͑1͒…”

Section: Introductionmentioning

confidence: 99%

On collisional energy transfer in recombination and dissociation reactions: A Wiener–Hopf problem and the effect of a near elastic peak

Zhu

Marcus

2008

The Journal of Chemical Physics

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The effect of the large impact parameter near-elastic peak of collisional energy transfer for unimolecular dissociation/bimolecular recombination reactions is studied. To this end, the conventional single exponential model, a biexponential model that fits the literature classical trajectory data better, a model with a singularity at zero energy transfer, and the most realistic model, a model with a near-singularity, are fitted to the trajectory data in the literature. The typical effect of the energy transfer on the recombination rate constant is maximal at low pressures and this region is the one studied here. The distribution function for the limiting dissociation rate constant k 0 at low pressures is shown to obey a Wiener-Hopf integral equation and is solved analytically for the first two models and perturbatively for the other two. For the single exponential model, this method yields the trial solution of Troe. The results are applied to the dissociation of O 3 in the presence of argon, for which classical mechanical trajectory data are available. The k 0 's for various models are calculated and compared, the value for the near-singularity model being about ten times larger than that for the first two models. This trend reflects the contribution to the cross section from collisions with larger impact parameter. In the present study of the near-singularity model, it is found that k 0 is not sensitive to reasonable values for the lower bound. Energy transfer values ͗⌬E͘'s are also calculated and compared and can be similarly understood. However, unlike the k 0 values, they are sensitive to the lower bound, and so any comparison of a classical trajectory analysis for ͗⌬E͘'s with the kinetic experimental data needs particular care.

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“…KKS state that their NB study is the first unambiguous observation of vibrational relaxation and incubation in a molecule larger than a triatomic and only one triatomic has shown unambiguous incubation. 2 Earlier schlieren shock-tube experiments using cyclohexene 3 gave some indication of an incubation time. 4 Usually, only unimolecular fall-off rate coefficients are available, so the additional information provided by this new shock-tube study of NB provides an excellent opportunity to investigate the interplay between vibrational energy transfer and unimolecular reaction over a very wide temperature range.…”

Section: Introductionmentioning

confidence: 99%

Vibrational energy transfer in shock-heated norbornene

Barker

King

1995

The Journal of Chemical Physics

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Recently, Kiefer et al. ͓J. H. Kiefer, S. S. Kumaran, and S. Sundaram, J. Chem. Phys. 99, 3531 ͑1993͔͒ studied shock-heated norbornene ͑NB͒ in krypton bath gas using the laser-schlieren technique and observed vibrational relaxation, unimolecular dissociation ͑to 1,3-cyclopentadiene and ethylene͒, and dissociation incubation times. Other workers have obtained an extensive body of high-pressure limit unimolecular reaction rate data at lower temperatures using conventional static and flow reactors. In the present work, we have developed a vibrational energy transfer-unimolecular reaction model based on steady-state RRKM calculations and time-dependent master equation calculations to satisfactorily describe all of the NB data ͑incubation times, vibrational relaxation times, and unimolecular rate coefficients͒. The results cover the temperature range from ϳ300 to 1500 K and the excitation energy range from ϳ1 000 to 18 000 cm Ϫ1 . Three different models ͑based on the exponential step-size distribution͒ for the average downward energy transferred per collision, ͗⌬E͘ down were investigated. The experimental data are too limited to enable the identification of a preferred model and it was not possible to determine whether the average ͗⌬E͘ down is temperature dependent. However, all three ͗⌬E͘ down models depend linearly on vibrational energy and it is concluded that standard unimolecular reaction rate codes must be revised to include energy-dependent microcanonical energy transfer parameters. The choice of energy transfer model affects the deduced reaction critical energy by more than 2 kcal mol Ϫ1 , however, which shows the importance of energy transfer in determining thermochemistry from unimolecular reaction fall-off data. It is shown that a single set of Arrhenius parameters gives a good fit of all the low temperature data and the shock-tube data extrapolated to the high pressure limit, obviating the need to invoke a change in reaction mechanism from concerted to diradical for high temperature conditions. Some possible future experiments are suggested.

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The vibrational relaxation and pyrolysis of shock heated nitrous oxide

Cited by 26 publications

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A study of N₂O decomposition rate constant at high temperature: Application to the reduction of nitrous oxide by hydrogen

A study of N₂O decomposition rate constant at high temperature: Application to the reduction of nitrous oxide by hydrogen

On collisional energy transfer in recombination and dissociation reactions: A Wiener–Hopf problem and the effect of a near elastic peak

Vibrational energy transfer in shock-heated norbornene

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The vibrational relaxation and pyrolysis of shock heated nitrous oxide

Cited by 26 publications

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A study of N2O decomposition rate constant at high temperature: Application to the reduction of nitrous oxide by hydrogen

A study of N2O decomposition rate constant at high temperature: Application to the reduction of nitrous oxide by hydrogen

On collisional energy transfer in recombination and dissociation reactions: A Wiener–Hopf problem and the effect of a near elastic peak

Vibrational energy transfer in shock-heated norbornene

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A study of N₂O decomposition rate constant at high temperature: Application to the reduction of nitrous oxide by hydrogen

A study of N₂O decomposition rate constant at high temperature: Application to the reduction of nitrous oxide by hydrogen