Highly resolved absolute cross-sections for dissociative electron attachment to SF5CF3

Karola Graupner, Thomas Field, C.A. Mayhew, I.I. Fabrikant, T.M. Miller, M. Braun, M.W. Ruf, H. Hotop, Lucy Graham

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Using two complementary experimental methods, we have measured partial (mass-resolved) cross-sections for dissociative electron attachment to the molecule trifluoromethyl sulfurpentafluoride (SF5CF3) at the gas temperature T-G = 300 K over a broad range of electron energies (E = 0.001-12 eV). The absolute scale for these cross-sections was obtained with reference to the thermal (T = 300 K) rate coefficient for anion formation (8.0(3) x 10(-8) cm(3) s(-1)). Below 1 eV, SF5- is the dominant product anion and formed through the lowest anion state which cuts the neutral SF5CF3 potential close to the S-C equilibrium distance. The highly resolved laser photoelectron attachment data exhibit a downward Wigner cusp at 86meV, indicating that the nu(4)(alpha(1)) vibrational mode is important for the primary attachment dynamics. Both SF5- and F- anions are formed with similar yields through the first excited resonance located near 3.6eV. Towards higher energies, the anions CF3-, SF4-, and SF3- are also produced. Summation of the partial cross-sections yields a total absolute cross-section for anion formation over the energy range 0.001-12 eV. This is used to calculate the dependence of the rate coefficient for dissociative electron attachment over a broad range of electron temperatures for the fixed gas temperature T-G = 300 K; good agreement is found between the calculated values and those obtained in a drift tube experiment. In addition to the experimental work, semiempirical R-matrix calculations have been Carried out for the energy dependence of the cross-section for SF5- formation. The experimental findings are semi-quantitatively recovered. (C) 2008 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)113-122
Number of pages10
JournalInternational Journal of Mass Spectrometry
Volume277
Issue number1-3
DOIs
Publication statusPublished - 01 Nov 2008

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Condensed Matter Physics
  • Instrumentation

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