Recombination and Disproportionation of NH2 Radicals

Salzman, John D.; Bair, Edward J.

doi:10.1063/1.1725789

Cited by 27 publications

(23 citation statements)

References 4 publications

(1 reference statement)

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“…-I at a pressure of a few Torr argon, which is the same order of magnitude as the other determinations [15,68].…”

Section: IVsupporting

confidence: 74%

“…This value looks fairly high for such a radical reaction, even though it should be lowered by about 20~ according to a revised value of G (NH2) [69]. It is, however, in fairly good agreement The intercept obtained at zero pressure shows the existence of a bimolecular low pressure limit in agreement withHanes and Bair [48] and Salzman and Bair [68]. Ghering et al [51] and Duncanson et al [25] also detected such a bimolecular low pressure limit.…”

Section: IVsupporting

confidence: 74%

“…-I s -1)[15] which confirms the observation of Salzman and Bair (k8(0) = 0.76 x 10 -12 cm 3 molec. -I s -1)[68], is still unclear. Such a pressure independent rate constant can be attributed to Reactions (8b), (8c) or (8d).…”

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confidence: 99%

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Reactivity and kinetic properties of the NH2 radical in the gas phase

Lesclaux

1984

Reviews of Chemical Intermediates

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“…-I at a pressure of a few Torr argon, which is the same order of magnitude as the other determinations [15,68].…”

Section: IVsupporting

confidence: 74%

Section: IVsupporting

confidence: 74%

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Reactivity and kinetic properties of the NH2 radical in the gas phase

Lesclaux

1984

Reviews of Chemical Intermediates

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“…Rate constants at low temperatures for the NH 2 + NH 2 reaction (R3) have been reported by several groups. ,,,− ,− The early work, much of which was reviewed by Lesclaux, involved relative measurements of the amino radical and suffered from uncertainty in the determination of the starting concentration of NH 2 , and the data are scattered. Bair and co-workers , studied R3 at very low pressures, where it is difficult to distinguish between recombination and disproportionation.…”

Section: Kinetics and Theorymentioning

confidence: 99%

On the Rate Constant for NH₂+HO₂ and Third-Body Collision Efficiencies for NH₂+H(+M) and NH₂+NH₂(+M)

et al. 2021

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In low temperature ash photolysis of NH 3 /O 2 /N 2 mixtures, the NH 2 consumption rate and the product distribution is controlled by the reactions NH 2 + HO 2 → products (R1), NH 2 + H (+M) → NH 3 (+M) (R2), and NH 2 + NH 2 (+M) → N 2 H 4 (+M) (R3). In the present work, published ash photolysis experiments by, among others, Cheskis and coworkers, are re-interpreted, using recent direct measurements of NH 2 + H (+N 2 ) and NH 2 + NH 2 (+N 2 ) from Altinay and Macdonald. To facilitate analysis of the FP data, relative third body collision eciencies compared to N 2 for R2 and R3 were calculated for O 2 and NH 3 , as well as for other selected molecules. Results were in good agreement with the limited experimental data. Based on reported NH 2 decay rates in ash photolysis of NH 3 /O 2 /N 2 , a rate constant for NH 2 + HO 2 → NH 3 + O 2 (R1a) of k 1a = 1.5(±0.5)•10 14 cm 3 mol −1 s −1 at 295 K was derived. This value is higher than earlier determinations based on the FP results, but in good agreement with recent theoretical work. Kinetic modeling of reported 1 N 2 O yields indicates that NH 2 + HO 2 → H 2 NO + O (R1c) is competing with R1a, but perturbation experiments with addition of CH 4 indicate that it is not a dominating channel.Measured HNO proles indicate that this component is formed directly by NH 2 + HO 2 → HNO + H 2 O (R1b), but theoretical work indicates that R1b is only a minor channel. Based on this analysis, we estimate k 1c = 2.5•10 13 cm 3 mol −1 s −1 and k 1b = 2.5•10 12 cm 3 mol −1 s −1 at 295 K, with signicant uncertainty margins.

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“…V. PHELPS AND R. E. VOSHALL production of 0at electron energies of less than 0.5 e V using electron-beam techniques has recently been shown by Chantry16 to be strongly dependent on the gas temperature so that the 0production observed 5 at electron energies below 0.21 eV can be attributed to thermally excited N 2 0 molecules as proposed by Kaufman. 7 Since the electron-energy distribution for thermal electrons is known, we can use the results to set upper limits to the attachment cross section. 2, we conclude that for thermal electrons (E/N~2X10-18 V·cm 2 ) the effective two-body rate coefficient is less than 3 X 10-15 cm 3 /sec.…”

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confidence: 99%

Reactions of Nitrogen–Hydrogen Radicals. III. Formation and Disappearance of NH Radicals in the Photolysis of Ammonia

Mantei

Bair

1968

The Journal of Chemical Physics

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The rates of formation and disappearance of the NH biradical in the ground and first-excited vibrational states were measured by kinetic spectroscopy following flash photolysis of mixtures of ammonia and inert gases. The delay in the appareance of NH following a 25-!,sec photolysis flash shows that it is formed by secondary reactions of the primary photolysis products, either NH2+ NH2 or NH2+ H. A large proportion of the observed NH is initially formed in the v" = 1 vibrational state, which disappears an order of magnitude faster than NH(v"=O). The disappearance of NH (v" = 0) is pressure dependent and in the falloff region at 1 torr, 300 o K. The rate of disappearance is rapid and is consistent with NH + NHa insertion. At the highpressure lin1it the rate constant for this reaction is k,=1.0±0.3XlO IO Iiter/mole·sec. The reaction has a small negative energy of activation. The high rate of NH disappearance accounts for the small range of conditions under which it can be observed. Implications of the results to the mechanism of biradical insertion reactions are discussed.

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Recombination and Disproportionation of NH2 Radicals

Cited by 27 publications

References 4 publications

Reactivity and kinetic properties of the NH2 radical in the gas phase

Reactivity and kinetic properties of the NH2 radical in the gas phase

On the Rate Constant for NH₂+HO₂ and Third-Body Collision Efficiencies for NH₂+H(+M) and NH₂+NH₂(+M)

Reactions of Nitrogen–Hydrogen Radicals. III. Formation and Disappearance of NH Radicals in the Photolysis of Ammonia

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Recombination and Disproportionation of NH2 Radicals

Cited by 27 publications

References 4 publications

Reactivity and kinetic properties of the NH2 radical in the gas phase

Reactivity and kinetic properties of the NH2 radical in the gas phase

On the Rate Constant for NH2+HO2 and Third-Body Collision Efficiencies for NH2+H(+M) and NH2+NH2(+M)

Reactions of Nitrogen–Hydrogen Radicals. III. Formation and Disappearance of NH Radicals in the Photolysis of Ammonia

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On the Rate Constant for NH₂+HO₂ and Third-Body Collision Efficiencies for NH₂+H(+M) and NH₂+NH₂(+M)