skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Electron-impact dissociative ionization of ethylene

Abstract

The ionization rates of the electron-impact ionization and dissociative ionization of ethylene for two typical cases: thermal plasmas with an electron temperature in the range between 1000 and 24 000 K; and nonthermal plasmas with the reduced electric field in the range between 10 and 200 Td are presented. Electron-impact dissociative ionization rates were calculated for 11 fragment ions of ethylene in the case of low temperature thermal plasma, and in a case of nonthermal ionized mixture of argon and ethylene. Dissociative ionization cross sections were calculated using a semiempirical binary-encounter bethe (BEB) model [Y. K. Kim and M. E. Rudd, Phys. Rev. A 50, 3954 (1994)], with each of the four most dominant fragments, C{sub 2}H{sub 4}{sup +}, C{sub 2}H{sub 3}{sup +}, C{sub 2}H{sub 2}{sup +}, and H{sup +}, being associated with a single molecular orbital. Calculated cross sections are used in this analysis due to the fact that the existing experimental data are the least accurate in the threshold region and the calculated results can improve the accuracy in that region. Also, the procedure may be extended to molecules for which experimental data are not available.

Authors:
;  [1];  [2]
  1. Department of Physics, Old Dominion University, Norfolk, Virginia 23529 (United States)
  2. Air Force Research Laboratory, Propulsion Directorate, WPAFB, Ohio 45433 (United States)
Publication Date:
OSTI Identifier:
20974582
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 73; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevA.73.022711; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ARGON; CARBON COMPOUNDS; COMPUTER CALCULATIONS; CROSS SECTIONS; DISSOCIATION; ELECTRIC FIELDS; ELECTRON TEMPERATURE; ELECTRONS; ETHYLENE; HEAVY IONS; HYDROGEN COMPOUNDS; HYDROGEN IONS 1 PLUS; IONIZATION; MIXTURES; MOLECULAR ORBITAL METHOD; MOLECULES; PLASMA; TEMPERATURE RANGE 0065-0273 K

Citation Formats

Popovic, S., Vuskovic, L., and Williams, S. Electron-impact dissociative ionization of ethylene. United States: N. p., 2006. Web. doi:10.1103/PHYSREVA.73.022711.
Popovic, S., Vuskovic, L., & Williams, S. Electron-impact dissociative ionization of ethylene. United States. doi:10.1103/PHYSREVA.73.022711.
Popovic, S., Vuskovic, L., and Williams, S. Wed . "Electron-impact dissociative ionization of ethylene". United States. doi:10.1103/PHYSREVA.73.022711.
@article{osti_20974582,
title = {Electron-impact dissociative ionization of ethylene},
author = {Popovic, S. and Vuskovic, L. and Williams, S.},
abstractNote = {The ionization rates of the electron-impact ionization and dissociative ionization of ethylene for two typical cases: thermal plasmas with an electron temperature in the range between 1000 and 24 000 K; and nonthermal plasmas with the reduced electric field in the range between 10 and 200 Td are presented. Electron-impact dissociative ionization rates were calculated for 11 fragment ions of ethylene in the case of low temperature thermal plasma, and in a case of nonthermal ionized mixture of argon and ethylene. Dissociative ionization cross sections were calculated using a semiempirical binary-encounter bethe (BEB) model [Y. K. Kim and M. E. Rudd, Phys. Rev. A 50, 3954 (1994)], with each of the four most dominant fragments, C{sub 2}H{sub 4}{sup +}, C{sub 2}H{sub 3}{sup +}, C{sub 2}H{sub 2}{sup +}, and H{sup +}, being associated with a single molecular orbital. Calculated cross sections are used in this analysis due to the fact that the existing experimental data are the least accurate in the threshold region and the calculated results can improve the accuracy in that region. Also, the procedure may be extended to molecules for which experimental data are not available.},
doi = {10.1103/PHYSREVA.73.022711},
journal = {Physical Review. A},
number = 2,
volume = 73,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}
  • Absolute cross sections and mass-spectral cracking patterns are reported for ionization of the free radicals CD/sub 3/ and CD/sub 2/. Such data for free radicals have previously been unmeasured because of their high reactivity. In this work, a beam of pure free radicals is generated by charge-transfer neutralization of a fast ion beam and is ionized by a crossed electron beam. With this approach, complete collection of mass-selected parent and fragment ions is obtained, permitting measurement of quantitative cross sections.
  • Absolute cross sections for electron-impact ionization of the SiF free radical from threshold to 200 eV are presented for formation of the parent SiF/sup +/ ion and the fragment Si/sup +/ and F/sup +/ ions. A fast beam of SiF is prepared by charge transfer neutralization of an SiF/sup +/ beam. The radicals form in the ground electronic state and predominantly in their ground vibrational state, as shown by agreement of the measured ionization threshold with the ionization potential. The absolute cross section for SiF..-->..SiF/sup +/ at 70 eV is 3.90 +- 0.32 A/sup 2/. The ratio of cross sectionsmore » for formation of Si/sup +/ to that for SiF/sup +/ at 70 eV is 0.528 +- 0.024; the ratio for formation of F/sup +/ to that of SiF/sup +/ is 0.060 +- 0.008. The observed threshold energy for Si/sup +/ formation indicates the importance of ion pair formation SiF..-->..Si/sup +/+F/sup -/. Breaks in the cross section at 14.3 and 17 eV are assigned as dissociative ionization thresholds.« less
  • The relative differential partial ionization cross sections for the production of ionic fragments of SF{sub 6} molecule under impact of 10-20 keV electrons have been measured using an ejected electron-produced ion coincidence technique in a crossed beam apparatus with a time-of-flight analysis of the ions. The detection angle of the ejected electrons of nondiscriminated energies was kept at 90 deg. with respect to the incident electron-beam direction. The 14 ionic fragments: SF{sub 5}{sup +}, SF{sub 4}{sup +}, SF{sub 3}{sup +}, SF{sub 2}{sup +}, SF{sup +}, S{sup +}, F{sup +}, SF{sub 4}{sup 2+}, SF{sub 3}{sup 2+}, SF{sub 2}{sup 2+}, S{sup 2+},more » F{sup 2+}, SF{sub 3}{sup 3+}, and S{sup 3+} resulting from the dissociative ionization of the SF{sub 6} molecule were identified and their relative production cross sections have been measured. The branching ratios of 8 ionic fragments SF{sub m}{sup n+} (m=1 to 5 and n=1 to 3) as a function of impact energy have been determined. These ratios are found to have an almost a constant value over the considered impact energy range within the experimental uncertainty of the measurements. For the investigated impact energies, no previous data or theoretical calculations exist for a direct comparison with the present results.« less