Dissociative electron attachment to C2F5 radicals

Haughey, Sharon; Field, Thomas A.; Langer, Judith; Shuman, Nicholas S.; Miller, Thomas M.; Friedman, Jeffrey F.; Viggiano, Albert A.

doi:10.1063/1.4738759

Cited by 17 publications

(16 citation statements)

References 47 publications

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“…The technique, dubbed variable electron and neutral density attachment mass spectrometry (VENDAMS), 11 has been applied to measure rate constants and product distributions of mutual neutralization [12][13][14][15][16] and electron attachment to short-lived species such as radicals. 11,17,18 Here, a variation of the technique is used to determine thermal DR rate constants. Unlike other VENDAMS applications, the method does not involve electron attachment; however, for consistency the acronym is retained.…”

Section: Introductionmentioning

confidence: 99%

A novel technique for measurement of thermal rate constants and temperature dependences of dissociative recombination: CO2+, CF3+, N2O+, C7H8+, C7H7+, C6H6+, C6H5+, C5H6+, C4H4+, and C3H3+

Fournier

Shuman

Melko

et al. 2013

The Journal of Chemical Physics

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A novel technique using a flowing afterglow-Langmuir probe apparatus for measurement of temperature dependences of rate constants for dissociative recombination (DR) is presented. Low (~10(11) cm(-3)) concentrations of a neutral precursor are added to a noble gas∕electron afterglow plasma thermalized at 300-500 K. Charge exchange yields one or many cation species, each of which may undergo DR. Relative ion concentrations are monitored at a fixed reaction time while the initial plasma density is varied between 10(9) and 10(10) cm(-3). Modeling of the decrease in concentration of each cation relative to the non-recombining noble gas cation yields the rate constant for DR. The technique is applied to several species (O2(+), CO2(+), CF3(+), N2O(+)) with previously determined 300 K values, showing excellent agreement. The measurements of those species are extended to 500 K, with good agreement to literature values where they exist. Measurements are also made for a range of CnHm(+) (C7H7(+), C7H8(+), C5H6(+), C4H4(+), C6H5(+), C3H3(+), and C6H6(+)) derived from benzene and toluene neutral precursors. CnHm(+) DR rate constants vary from 8-12 × 10(-7) cm(3) s(-1) at 300 K with temperature dependences of approximately T(-0.7). Where prior measurements exist these results are in agreement, with the exception of C3H3(+) where the present results disagree with a previously reported flat temperature dependence.

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Section: Introductionmentioning

confidence: 99%

A novel technique for measurement of thermal rate constants and temperature dependences of dissociative recombination: CO2+, CF3+, N2O+, C7H8+, C7H7+, C6H6+, C6H5+, C5H6+, C4H4+, and C3H3+

Fournier

Shuman

Melko

et al. 2013

The Journal of Chemical Physics

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“…25 In particular, no data on thermal electron attachment to fluorocarbon radicals existed; these data are particularly important because they are needed for predictive modeling of plasma etching of semiconductor material, a vital industrial process involved in the fabrication of microelectronics. We have previously reported rate constants and product branching for most small fluorocarbon radicals (CF 2 , CF 3 , C 2 F 3 , C 2 F 5 , 1-C 3 F 7 , 2-C 3 F 7 , 3-C 3 F 5 ) from 300 to 600 K. 11,18,19 In concert, a separate beam experiment provided relative cross sections of attachment to CF 2 10 and C 2 F 5 18 as a function of electron energy up to 10 eV. Kinetic modeling was used to extrapolate these data to conditions most relevant to plasma etching, namely gas temperatures around 300 K and electron temperatures up to 10 000 K. The CF 3 system is particularly intriguing because, due to a mild endothermicity for dissociative attachment, electron attachment (1) proceeds via a competition between associative attachment (2a), dissociative attachment yielding F − (2b), and autodetachment (2c),…”

Section: Introductionmentioning

confidence: 99%

Electron attachment to CF3 and CF3Br at temperatures up to 890 K: Experimental test of the kinetic modeling approach

Shuman

Miller

Viggiano

et al. 2013

The Journal of Chemical Physics

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Thermal rate constants and product branching fractions for electron attachment to CF3Br and the CF3 radical have been measured over the temperature range 300-890 K, the upper limit being restricted by thermal decomposition of CF3Br. Both measurements were made in Flowing Afterglow Langmuir Probe apparatuses; the CF3Br measurement was made using standard techniques, and the CF3 measurement using the Variable Electron and Neutral Density Attachment Mass Spectrometry technique. Attachment to CF3Br proceeds exclusively by the dissociative channel yielding Br(-), with a rate constant increasing from 1.1 × 10(-8) cm(3) s(-1) at 300 K to 5.3 × 10(-8) cm(3) s(-1) at 890 K, somewhat lower than previous data at temperatures up to 777 K. CF3 attachment proceeds through competition between associative attachment yielding CF3 (-) and dissociative attachment yielding F(-). Prior data up to 600 K showed the rate constant monotonically increasing, with the partial rate constant of the dissociative channel following Arrhenius behavior; however, extrapolation of the data using a recently proposed kinetic modeling approach predicted the rate constant to turn over at higher temperatures, despite being only ~5% of the collision rate. The current data agree well with the previous kinetic modeling extrapolation, providing a demonstration of the predictive capabilities of the approach.

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“…Considering electron interaction with radicals in the gas phase, to our knowledge, only those with fluorocarbon radicals have been investigated to date, including measurements of absolute elastic cross sections for CF 2 CF 3 [26,27] and DEA processes for CF 2 and C 2 F 5 [28,29]. In the latter experiments, the target radical beam has been obtained by either pyrolysis or microwave discharge.…”

Section: *Correspondence To: E-mail Sylwiaptasinska1@ndedu; Tel + mentioning

confidence: 99%

Characterization of Neutral Radicals from a Dissociative Electron Attachment Process

et al. 2017

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Dissociative electron attachment to C2F5 radicals

Cited by 17 publications

References 47 publications

A novel technique for measurement of thermal rate constants and temperature dependences of dissociative recombination: CO2+, CF3+, N2O+, C7H8+, C7H7+, C6H6+, C6H5+, C5H6+, C4H4+, and C3H3+

A novel technique for measurement of thermal rate constants and temperature dependences of dissociative recombination: CO2+, CF3+, N2O+, C7H8+, C7H7+, C6H6+, C6H5+, C5H6+, C4H4+, and C3H3+

Electron attachment to CF3 and CF3Br at temperatures up to 890 K: Experimental test of the kinetic modeling approach

Characterization of Neutral Radicals from a Dissociative Electron Attachment Process

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