Measurement of thermal electron dissociative attachment rate constants for halogen gases using a flowing afterglow technique

Sides, G. D.; Tiernan, T. O.; Hanrahan, Robert J.

doi:10.1063/1.433294

Cited by 57 publications

(16 citation statements)

References 25 publications

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“…Calculated cross sections differ substantially from each other [11][12][13]. Experimental thermal rate constants vary by an order of magnitude [16,17], and beam experiments have shown, each seemingly conclusively but obviously contradictory, either s-wave [1,2] or p-wave [8] behavior. Here, we aim to reconcile a portion of these disparate literature results, moving closer to solving the question of DEA to F 2 .…”

Section: Introductionmentioning

confidence: 81%

Thermal electron attachment to F2

et al. 2013

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Rate constants have been measured from 300 to 700 K for thermal electron attachment to F 2 using two flowing afterglow-Langmuir probe apparatuses. Dissociative attachment yielding F − is observed with a rate constant of 5.0 ± 1.3 × 10 −9 cm 3 s −1 at 300 K, rising to 9.6 ± 2.4 × 10 −9 cm 3 s −1 at 700 K, well below the previously accepted values of McCorkle et al. [D. L. McCorkle, L. G. Christophorou, A. A. Christodoulides, and L. Pichiarella, J. Chem. Phys. 85, 1966 (1986)]. The absolute concentration of F 2 reaching the afterglow is verified by measuring the near-collisional rate constant (4.5 ± 1.5 × 10 −10 cm 3 s −1) for Ar + + F 2 →ArF + + F. Prior attempts to apply R-matrix calculations to the F 2 + e − system have failed to explain previously reported thermal and nonthermal attachment rate constants along with high-resolution, low-energy attachment cross sections. The present results are reproduced exceptionally well by R-matrix calculations employing previously calculated resonance widths without adjustment.

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Section: Introductionmentioning

confidence: 81%

Thermal electron attachment to F2

et al. 2013

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“…We see that the McCorkle et al measurements and the calculations fit the group reasonably well. The major deviations are the Schneider and Brau C6~) measurements in both Ar and N2, which were performed in the afterglow of an electron beam ionized discharge, and the very low energy Sides et al 42 thermal flowing afterglow measurements. We have seen with Cl2 and will see with HCI that the measurements of the Los Alamos group yield rate coefficients much higher than all other measurements, which makes their measurement technique suspect.…”

Section: Dissociative Attachment: F 2 At-e--+ F-+ Fmentioning

confidence: 99%

A critical evaluation of low-energy electron impact cross sections for plasma processing modeling. I: Cl2, F2, and HCl

Morgan

1992

Plasma Chem Plasma Process

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“…The first trihalide anion to be detected in the gas phase was I 3in 1928, 18 followed by Cl 3in 1958, 19 while the gas-phase detection of Br 3and F 3was realized only one decade ago. 20,21 These species are all stable against dissociation by either exit channels, eqs 1 and 2, with channel 1 being in all cases the thermodynamically favored one. [22][23][24]…”

Section: Introductionmentioning

confidence: 99%

Application of the Valence Bond Mixing Configuration Diagrams to Hypervalency in Trihalide Anions: A Challenge to the Rundle−Pimentel Model

Braı̈da

Hiberty

2008

J. Phys. Chem. A

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The X(3)(-) hypercoordinated anions (H, F, Cl, Br, I) are studied by means of the breathing-orbital valence bond ab initio method. The valence bond wave functions describe the different X(3)(-) complexes in terms of only six valence bond structures and yield energies relative to the two exit channels, X(2) + X(-) and X(2)(-) + X(*), in very good agreement with reference CCSD(T) calculations. Although H(3)(-) is unstable and dissociates to H(2) + H(-), all the trihalogen anions are stable intermediates, Br(3)(-) and I(3)(-) being more stable than F(3)(-) and Cl(3)(-). As a challenge to the traditional Rundle-Pimentel model, the different energies of the hypercoordinated species relative to the normal-valent dissociation products X(2) + X(-) are interpreted in terms of valence bond configuration mixing diagrams and found to correlate with a single parameter of the X(2) molecule, its singlet-triplet energy gap. Examination of the six-structure wave functions show that H(3)(-), Cl(3)(-), Br(3)(-), and I(3)(-) share the same bonding picture and can be mainly described in terms of the interplay of two Lewis structures. On the other hand, F(3)(-) is bonded in a different way and possesses a significant three-electron bonding character that is responsible for the dissociation of this complex to F(2)(-) + F(*), instead of the more stable products F(2) + F(-). This counterintuitive preference for the thermodynamically disfavored exit channel is found to be an experimental manifestation of the large charge-shift resonance energy that generally characterizes fluorine-containing bonds.

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Measurement of thermal electron dissociative attachment rate constants for halogen gases using a flowing afterglow technique

Cited by 57 publications

References 25 publications

Thermal electron attachment to F2

Thermal electron attachment to F2

A critical evaluation of low-energy electron impact cross sections for plasma processing modeling. I: Cl2, F2, and HCl

Application of the Valence Bond Mixing Configuration Diagrams to Hypervalency in Trihalide Anions: A Challenge to the Rundle−Pimentel Model

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