Communication: Transfer ionization in a thermal reaction of a cation and anion: Ar+ with Br− and I−

Shuman, Nicholas S.; Miller, Thomas M.; Johnsen, Rainer; Viggiano, Albert A.

doi:10.1063/1.4828455

Cited by 3 publications

(3 citation statements)

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“…The data sets upper limits on HOCO + and HCOOH + channels, with signals barely differentiable from the noise. I + arises from two sources: Ar + + CH 3 I as detailed elsewhere in this work and a transfer ionization product channel in the mutual neutralization of Ar + + I – (i.e., yielding Ar + I + + e – ) . Finally, H 2 + is not easily observable with the present quadrupole mass spectrometer, and no determination of this channel has been made.…”

Section: Results and Analysismentioning

confidence: 90%

“…The MN rate constant of Ar + with I − has been reported (2 × 10 −8 cm 3 s −1 ). 25 These data are only well fit assuming that the MN reaction of I + + I − proceeds slowly, with a rate constant on the order of 10 −9 cm 3 s −1 or lower. This is in agreement with the ∼2 × 10 −9 cm 3 s −1 value predicted using an empirically derived formula for the MN rate constants of reactions involving two monatomic species.…”

Section: ■ Results and Analysismentioning

confidence: 98%

“…This is in agreement with the ∼2 × 10 −9 cm 3 s −1 value predicted using an empirically derived formula for the MN rate constants of reactions involving two monatomic species. 25 A significant portion of the increase in the I + relative abundance is due to a transfer ionization channel (i.e., Ar + + I − → Ar + I + + e). 26 The rate constants for MN of both CH 2 + and CH 3 + with I − at 300 K were measured here using methods described elsewhere.…”

Section: ■ Results and Analysismentioning

confidence: 99%

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Kinetics and Product Branching Fractions of Reactions between a Cation and a Radical: Ar⁺ + CH₃ and O₂⁺ + CH₃

et al. 2015

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A novel technique is described for the measurement of rate constants and product branching fractions of thermal reactions between cation and radical species. The technique is a variant of the variable electron and neutral density attachment mass spectrometry (VENDAMS) method, employing a flowing afterglow-Langmuir probe apparatus. A radical species is produced in situ via dissociative electron attachment to a neutral precursor; this allows for a quantitative derivation of the radical concentration and, as a result, a quantitative determination of rate constants. The technique is applied to the reactions of Ar(+) and O2(+) with CH3 at 300 K. The Ar(+) + CH3 reaction proceeds near the collisional rate constant of 1.1 × 10(-9) cm(3) s(-1) and has three product channels: → CH3(+) + Ar (k = 5 ± 2 × 10(-10) cm(3) s(-1)), → CH2(+) + H + Ar (k = 7 ± 2 × 10(-10) cm(3) s(-1)), → CH(+) + H2 + Ar (k = 5 ± 3 × 10(-11) cm(3) s(-1)). The O2(+) + CH3 reaction is also efficient, with direct charge transfer yielding CH3(+) as the primary product channel. Several results needed to support these measurements are reported, including the kinetics of Ar(+) and O2(+) with CH3I, electron attachment to CH3I, and mutual neutralization of CH3(+) and CH2(+) with I(-).

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Section: Results and Analysismentioning

confidence: 90%

Section: ■ Results and Analysismentioning

confidence: 98%

Section: ■ Results and Analysismentioning

confidence: 99%

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Kinetics and Product Branching Fractions of Reactions between a Cation and a Radical: Ar⁺ + CH₃ and O₂⁺ + CH₃

et al. 2015

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Mutual neutralization of atomic rare-gas cations (Ne+, Ar+, Kr+, Xe+) with atomic halide anions (Cl−, Br−, I−)

Shuman

Miller

Johnsen

et al. 2014

The Journal of Chemical Physics

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We report thermal rate coefficients for 12 reactions of rare gas cations (Ne(+), Ar(+), Kr(+), Xe(+)) with halide anions (Cl(-), Br(-), I(-)), comprising both mutual neutralization (MN) and transfer ionization. No rate coefficients have been previously reported for these reactions; however, the development of the Variable Electron and Neutral Density Attachment Mass Spectrometry technique makes it possible to measure the difference of the rate coefficients for pairs of parallel reactions in a Flowing Afterglow-Langmuir Probe apparatus. Measurements of 18 such combinations of competing reaction pairs yield an over-determined data set from which a consistent set of rate coefficients of the 12 MN reactions can be deduced. Unlike rate coefficients of MN reactions involving at least one polyatomic ion, which vary by at most a factor of ∼3, those of the atom-atom reactions vary by at least a factor 60 depending on the species. It is found that the rate coefficients involving light rare-gas ions are larger than those for the heavier rare-gas ions, but the opposite trend is observed in the progression from Cl(-) to I(-). The largest rate coefficient is 6.5 × 10(-8) cm(3) s(-1) for Ne(+) with I(-). Rate coefficients for Ar(+), Kr(+), and Xe(+) reacting with Br2 (-) are also reported.

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Mutual neutralization of He+ with the anions Cl−, Br−, I−, and SF6−

Wiens

Shuman

Miller

et al. 2016

The Journal of Chemical Physics

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Mutual neutralization (MN) rate coefficients kMN for He(+) with the anions Cl(-), Br(-), I(-), and SF6 (-) are reported from 300 to 500 K. The measured rate coefficients may contain a contribution from transfer ionization, i.e., double ionization of the anion. The large rate coefficient for He(+) + SF6 (-) (2.4 × 10(-7) cm(3) s(-1) at 300 K) is consistent with earlier polyatomic MN results found to have a reduced mass dependence of μ(-1/2). Neutralization of He(+) by the atomic halides follows the trend observed earlier for Ne(+), Ar(+), Kr(+), and Xe(+) neutralized by atomic halides, kMN (Cl(-)) < kMN (Br(-)) < kMN (I(-)). Only an upper limit could be measured for the neutralization of He(+) by Cl(-). Predictions of the rate coefficients from a previously proposed simple model of atomic-atomic MN results are consistent with the present He(+)-halide rate coefficients. The temperature dependences are modestly negative for Br(-) and I(-), while that for SF6 (-) is small or negligible.

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Communication: Transfer ionization in a thermal reaction of a cation and anion: Ar+ with Br− and I−

Cited by 3 publications

References 12 publications

Kinetics and Product Branching Fractions of Reactions between a Cation and a Radical: Ar⁺ + CH₃ and O₂⁺ + CH₃

Kinetics and Product Branching Fractions of Reactions between a Cation and a Radical: Ar⁺ + CH₃ and O₂⁺ + CH₃

Mutual neutralization of atomic rare-gas cations (Ne+, Ar+, Kr+, Xe+) with atomic halide anions (Cl−, Br−, I−)

Mutual neutralization of He+ with the anions Cl−, Br−, I−, and SF6−

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Communication: Transfer ionization in a thermal reaction of a cation and anion: Ar+ with Br− and I−

Cited by 3 publications

References 12 publications

Kinetics and Product Branching Fractions of Reactions between a Cation and a Radical: Ar+ + CH3 and O2+ + CH3

Kinetics and Product Branching Fractions of Reactions between a Cation and a Radical: Ar+ + CH3 and O2+ + CH3

Mutual neutralization of atomic rare-gas cations (Ne+, Ar+, Kr+, Xe+) with atomic halide anions (Cl−, Br−, I−)

Mutual neutralization of He+ with the anions Cl−, Br−, I−, and SF6−

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Product

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Kinetics and Product Branching Fractions of Reactions between a Cation and a Radical: Ar⁺ + CH₃ and O₂⁺ + CH₃

Kinetics and Product Branching Fractions of Reactions between a Cation and a Radical: Ar⁺ + CH₃ and O₂⁺ + CH₃