Rotational effects in broadening factors of fall-off curves of unimolecular dissociation reactions

Troe, J.; Ushakov, V. G.

doi:10.1039/b101964n

Cited by 23 publications

(27 citation statements)

References 18 publications

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“…F c is known to decrease with increasing temperature at small T, before it increases at high T [14,[45][46][47]. This temperature range apparently corresponds to the intermediate regime.…”

Section: Approximate Representation Of K(t[m])mentioning

confidence: 91%

Thermal decomposition of ethylbenzene cations (C8H10+): experiments and modeling of falloff curves

Fernandez

Viggiano

Maergoiz

et al. 2005

International Journal of Mass Spectrometry

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“…F c is known to decrease with increasing temperature at small T, before it increases at high T [14,[45][46][47]. This temperature range apparently corresponds to the intermediate regime.…”

Section: Approximate Representation Of K(t[m])mentioning

confidence: 91%

Thermal decomposition of ethylbenzene cations (C8H10+): experiments and modeling of falloff curves

Fernandez

Viggiano

Maergoiz

et al. 2005

International Journal of Mass Spectrometry

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“…In addition, the minima of ( ) moved to values of < 1. Such effects were also found to gain importance when rotational effects were taken into account [10,18] such as this is the case for unimolecular bond fission and the reverse radical recombination reactions. A variety of expressions were proposed to approximate the resulting broadening factors, such as…”

Section: Fitting Of Experimental Falloff Curvesmentioning

confidence: 94%

“…It, therefore, appeared desirable to test alternative expressions for ( ) with respect to their performance in situations when cent is smaller than about 0.4. Besides simplified methods to predict cent such as suggested in [5,18], one also needs information about the uncertainties of 0 and ∞ obtained by fitting ( ) to limited parts of experimental falloff curves. This is the issue of the present article.…”

Section: Introductionmentioning

confidence: 99%

Representation of “Broad” Falloff Curves for Dissociation and Recombination Reactions

Troe¹,

Ushakov²

2014

Zeitschrift Für Physikalische Chemie

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Expressions for representing the pressure dependence of unimolecular dissociation and the reverse recombination reactions are compared. Situations are considered where the broadening of the corresponding falloff curves is particularly pronounced, i.e. where broadening factors at the center of the falloff curves, cent , are very small and falloff curves correspondingly become very "broad". Such situations arise when unimolecular reactions of molecules with large numbers of low-frequency modes and high-temperature situations are considered. Recombination reactions of polyatomic species in atmospheric chemistry and dissociation reactions of large molecules in combustion are the fields of application of the present results. While previously proposed expressions for asymmetric broadening factors showed artifacts when cent decreased to values below about 0.4, alternative functions are described which avoid these problems for situations where cent decreases to values far below 0.1.

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“…[8][9][10][11]. Finally, we incorporate the results into general expressions for broadening factors of unimolecular reactions 12,13 and compare the results with new analytical approximations for the rate constants as proposed in Ref. 14.…”

Section: Introductionmentioning

confidence: 98%

The dissociation/recombination reaction CH4 (+M) ⇔ CH3 + H (+M): A case study for unimolecular rate theory

Troe

Ushakov

2012

The Journal of Chemical Physics

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The dissociation/recombination reaction CH(4) (+M) ⇔ CH(3) + H (+M) is modeled by statistical unimolecular rate theory completely based on dynamical information using ab initio potentials. The results are compared with experimental data. Minor discrepancies are removed by fine-tuning theoretical energy transfer data. The treatment accounts for transitional mode dynamics, adequate centrifugal barriers, anharmonicity of vibrational densities of states, weak collision and other effects, thus being "complete" from a theoretical point of view. Equilibrium constants between 300 and 5000 K are expressed as K(c) = k(rec)/k(dis) = exp(52,044 K/T) [10(-24.65) (T/300 K)(-1.76) + 10(-26.38) (T/300 K)(0.67)] cm(3) molecule(-1), high pressure recombination rate constants between 130 and 3000 K as k(rec,∞) = 3.34 × 10(-10) (T/300 K)(0.186) exp(-T/25,200 K) cm(3) molecule(-1) s(-1). Low pressure recombination rate constants for M = Ar are represented by k(rec,0) = [Ar] 10(-26.19) exp[-(T/21.22 K)(0.5)] cm(6) molecule(-2) s(-1), for M = N(2) by k(rec,0) = [N(2)] 10(-26.04) exp[-(T/21.91 K)(0.5)] cm(6) molecule(-2) s(-1) between 100 and 5000 K. Weak collision falloff curves are approximated by asymmetric broadening factors [J. Troe and V. G. Ushakov, J. Chem. Phys. 135, 054304 (2011)] with center broadening factors of F(c) ≈ 0.262 + [(T - 2950 K)/6100 K](2) for M = Ar. Expressions for other bath gases can also be obtained.

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Rotational effects in broadening factors of fall-off curves of unimolecular dissociation reactions

Cited by 23 publications

References 18 publications

Thermal decomposition of ethylbenzene cations (C8H10+): experiments and modeling of falloff curves

Thermal decomposition of ethylbenzene cations (C8H10+): experiments and modeling of falloff curves

Representation of “Broad” Falloff Curves for Dissociation and Recombination Reactions

The dissociation/recombination reaction CH4 (+M) ⇔ CH3 + H (+M): A case study for unimolecular rate theory

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