Clear Experimental Evidence for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi></mml:math>-Wave Attachment-Threshold Behavior in Electron Attachment to Chlorine Molecules

Barsotti, S.; Ruf, M.-W.; Hotop, H.

doi:10.1103/physrevlett.89.083201

Cited by 28 publications

(27 citation statements)

References 32 publications

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“…By contrast, it has also been observed experimentally, in dissociative electron attachment to Cl 2 , that from ∼1 to 50 meV the p-wave attachment cross section follows the theoretically predicted σ ∝ E 1/2 form. 42 Thus, p-wave attachment cross sections drop to zero at zero energy. Therefore, it has not been possible with the electron beam data to estimate an absolute cross section for electron attachment to C 2 F 5 , but it has been possible with the VENDAMS data to determine rate constants at different temperatures.…”

Section: Discussionmentioning

confidence: 99%

Dissociative electron attachment to C2F5 radicals

Haughey

Field

Langer

et al. 2012

The Journal of Chemical Physics

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Dissociative electron attachment to the reactive C 2 F 5 molecular radical has been investigated with two complimentary experimental methods; a single collision beam experiment and a new flowing afterglow Langmuir probe technique. The beam results show that F − is formed close to zero electron energy in dissociative electron attachment to C 2 F 5 . The afterglow measurements also show that F − is formed in collisions between electrons and C 2 F 5 molecules with rate constants of 3.7 × 10 −9 cm 3 s −1 to 4.7 × 10 −9 cm 3 s −1 at temperatures of 300-600 K. The rate constant increases slowly with increasing temperature, but the rise observed is smaller than the experimental uncertainty of 35%.

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Section: Discussionmentioning

confidence: 99%

Dissociative electron attachment to C2F5 radicals

Haughey

Field

Langer

et al. 2012

The Journal of Chemical Physics

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“…The literature on low-energy electron attachment to homonuclear diatomic halogens is extensive, if at times conflicted [1][2][3][4][5][6][7][8]. These are the simplest systems that can undergo dissociative electron attachment (DEA) at thermal energies, making them attractive targets for theoretical methods aimed at handling the complexities of electron-molecule interactions.…”

Section: Introductionmentioning

confidence: 99%

Electron attachment to the interhalogen compounds ClF, ICl, and IBr

et al. 2016

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Thermal electron attachment rate coefficients for three interhalogen compounds (ClF, ICl, IBr) have been measured from 300 to 900 K at pressures of 1-2 Torr using a flowing afterglow-Langmuir probe apparatus. ClF attaches somewhat inefficiently (k = 7.5×10 −9 cm 3 s −1 ) at 300 K, with the rate coefficient rising to 1.7×10 −8 cm 3 s −1 at 700 K. At higher temperatures the apparent rate coefficient falls steeply; however, this is interpreted as an artifact due to decomposition on the walls of the inlet line. ICl attaches with even lower efficiency (k = 9.5×10 −10 cm 3 s −1 at 300 K) and a less steep increase with temperature. Attachment to IBr is too slow to confidently measure with the present experiment, with an upper limit on the rate coefficient of 10 −10 cm 3 s −1 from 300 to 600 K. Both ClF and ICl attach dissociatively to yield Cl − , likely exclusively, though F − or I − may be produced with limits of <2% and <5%, respectively. The ClF attachment was further explored through ab initio calculation of the ClF and ClF − potential energy curves and R-matrix calculations of the resonance parameters which were used then for calculations of the dissociative attachment cross sections and rate coefficients. While the magnitude of the attachment rate coefficient for ClF is similar to those for both Cl 2 and F 2 , the calculated cross sections show qualitatively different threshold behavior due to the s-wave contribution allowed by the lack of inversion symmetry. The v = 1 and 2 vibrational modes of ClF attach about three to four times faster than v = 0 and 3 at energies lower than ∼0.2 eV. The calculated rate coefficients are in good agreement with the experiment at 300 K and increase moderately less steeply with temperature.

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“…A critical analysis of the early and more recent low resolution data (Kurepa and Belic, 1978;Tam and Wong, 1978;Feketeova et al, 2003), based on their comparison with convoluted theoretical cross-section shapes (using appropriate energy distribution functions), reveals that they are in fact not contradictory to p-wave attachment . In a recent LPA experiment (energy width near threshold 1 meV) Barsotti et al (2002b) provided conclusive experimental evidence for p-wave behaviour of the attachment cross-section for Cl 2 by demonstrating the steep rise from threshold to a maximum located around 50 meV.…”

Section: B2 Electron Attachment To Fluorine and Chlorine Moleculesmentioning

confidence: 99%

“…When the molecules of interest are seeded in light carrier gas (such as helium) the kinetic energy of the molecules is raised substantially above its thermal value which -under conditions of weak extraction fields -results in a higher detection efficiency of the product ions due to dissociative attachment (Barsotti et al, 2002b). In a mixed supersonic beam, containing the seeded minority component with molecular mass m S at a fraction x and the atomic carrier gas with mass m C (fraction 1 À x), the flow velocity u S of the seeded component can be estimated (in the absence of velocity slip) by (Miller, 1988) …”

Section: Measurement Of Cross-sections For Electron Attachmentmentioning

confidence: 99%