High resolution study of anion formation in low-energy electron attachment to SF6 molecules in a seeded supersonic beam

  • M. Braun
  • S. Barsotti
  • S. Marienfeld
  • E. Leber
  • J. M. Weber
  • M.-W. Ruf
  • H. HotopEmail author
Fundamental Processes in the Gas Phase


Using two variants of the Laser Photoelectron Attachment (LPA) method involving a differentially-pumped, seeded supersonic beam (0.05% and 12.5% of SF6 molecules in helium carrier gas, nozzle temperatures T0= 300–600 K, stagnation pressures p0= 1–5 bar) and mass spectrometric ion detection, we have investigated the energy dependence of anion formation in low-energy electron collisions with SF6 molecules at high energy resolution. Using the standard LPA method, the yield for SF6- as well as SF5- and F- anions was studied with an energy width around 1 meV over the electron energy range 0–200 meV. In addition, a variant of the LPA method with extended energy range (denoted as EXLPA) was developed and applied to measure the yield for SF6- and SF5- formation over the energy range 0–1.5 eV with an energy width of about 20 meV. The cross-section for formation of SF6- decreases by five orders of magnitude over the range 1–500 meV and is only weakly dependent on nozzle temperature. The yield for SF5- formation shows — apart from a weak zero energy peak which grows strongly with rising temperature — a broad maximum (located around 0.6 eV for T0= 300 K and shifting to lower energies with rising T0) and a monotonical decrease towards higher energies. SF5- attachment spectra taken at elevated temperatures exhibit changes with rising stagnation pressure which directly reflect rovibrational cooling of the SF6 molecules with rising pressure. The SF5-/SF6- intensity ratio at near-zero energy and the low-energy shape of the broad peak in the SF5- spectra are used as thermometers for the internal temperature of the SF6 molecules in the seeded supersonic beam which (at p0= 1 bar) are found to be 50–100 K lower than the nozzle temperature. The energy dependence of the yield for F- formation is similar to that for SF6-, but the F- signals are three to four orders of magnitude lower than those for SF6-; in view of the rather high endothermicity of F- formation the origin of the F- signals is discussed in some detail.


Anion Formation Energy Width Stagnation Pressure Electron Attachment High Energy Resolution 
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  1. Electron molecule interactions and their applications, edited by L.G. Christophorou (Academic Press, New York 1984), Vol. 1 and 2 Google Scholar
  2. L.G. Christophorou, J.K. Olthoff, J. Phys. Chem. Ref. Data 29, 267 (2000) CrossRefGoogle Scholar
  3. E.P. Wigner, Phys. Rev. 73, 1002 (1948) CrossRefGoogle Scholar
  4. A. Chutjian, S.H. Alajajian, Phys. Rev. A 31, 2885 (1985) CrossRefPubMedGoogle Scholar
  5. D. Klar, M.-W. Ruf, H. Hotop, Chem. Phys. Lett. 189, 448 (1992); D. Klar, M.-W. Ruf, H. Hotop, Austr. J. Phys. 45, 263 (1992) Google Scholar
  6. F.B. Dunning, J. Phys. B 28, 1645 (1995) Google Scholar
  7. A. Schramm, J.M. Weber, J. Kreil, D. Klar, M.-W. Ruf, H. Hotop, Phys. Rev. Lett. 81, 778 (1998) Google Scholar
  8. P.-T. Howe, A. Kortyna, M. Darrach, A. Chutjian, Phys. Rev. A 64, 042706 (2001) CrossRefGoogle Scholar
  9. H. Hotop, M.-W. Ruf, M. Allan, I.I. Fabrikant, Adv. At. Mol. Opt. Phys. 49, 85 (2003) Google Scholar
  10. W.M. Hickam, R.E. Fox, J. Chem. Phys. 25, 642 (1956) Google Scholar
  11. C.E. Brion, Int. J. Mass Spectr. Ion Phys. 3, 197 (1969) CrossRefGoogle Scholar
  12. C.L. Chen, P.J. Chantry, J. Chem. Phys. 71, 3897 (1979) CrossRefGoogle Scholar
  13. L.E. Kline, D.K. Davies, C.L. Chen, P.J. Chantry, J. Appl. Phys. 50, 6789 (1979) CrossRefGoogle Scholar
  14. R.N. Compton, in Electronic and Atomic Collisions, edited by N. Oda, K. Takayanagi (North Holland Publ. Co., 1980), p. 251f Google Scholar
  15. S.R. Hunter, J.G. Carter, L.G. Christophorou, J. Chem. Phys. 90, 4879 (1989) CrossRefGoogle Scholar
  16. D. Smith, P. Span\(\check{{\rm e}}\)l, S. Matejcik, A. Stamatovic, T.D. Märk, T. Jaffke, E. Illenberger, Chem. Phys. Lett. 240, 481 (1995) CrossRefGoogle Scholar
  17. A. Rosa, F. Brüning, S.V.K. Kumar, E. Illenberger, Chem. Phys. Lett. 391, 361 (2004) Google Scholar
  18. M. Fenzlaff, R. Gerhard, E. Illenberger, J. Chem. Phys. 88, 149 (1988) CrossRefGoogle Scholar
  19. D. Edelson, J.E. Griffiths, K.B. McAfee Jr, J. Chem. Phys. 37, 917 (1962) CrossRefGoogle Scholar
  20. R.N. Compton, L.G. Christophorou, G.S. Hurst, P.W. Reinhardt, J. Chem. Phys. 45, 4634 (1966) Google Scholar
  21. J.M.S. Henis, C.A. Mabie, J. Chem. Phys. 53, 2999 (1970) Google Scholar
  22. P.W. Harland, J.C.J. Thynne, J. Phys. Chem. 75, 3517 (1971) CrossRefGoogle Scholar
  23. R.W. Odom, D.L. Smith, J.H. Futrell, J. Phys. B 8, 1349 (1975) Google Scholar
  24. M.S. Foster, J.L. Beauchamp, Chem. Phys. Lett. 31, 482 (1975) Google Scholar
  25. J.P. Astruc, R. Barbé, A. Lagrèze, J.P. Schermann, Chem. Phys. 75, 405 (1983) Google Scholar
  26. M. Vedel, J. André, G. Brincourt, Y. Zerega, G. Werth, J.P. Schermann, Appl. Phys. B 34, 229 (1984) CrossRefGoogle Scholar
  27. J.E. Delmore, A.D. Appelhans, J. Chem. Phys. 84, 6238 (1986) CrossRefGoogle Scholar
  28. A.D. Appelhans, J.E. Delmore, J. Chem. Phys. 88, 5561 (1988) CrossRefGoogle Scholar
  29. G. Brincourt, S. Rajab Pacha, R. Catella, Y. Zerega, J. André, Chem. Phys. Lett. 156, 573 (1989) CrossRefGoogle Scholar
  30. R.A. Popple, M.A. Durham, R.W. Marawar, B.G. Lindsay, K.A. Smith, F.B. Dunning, Phys. Rev. A 45, 247 (1992) CrossRefPubMedGoogle Scholar
  31. C.D. Finch, R. Parthasarathy, S.B. Hill, F.B. Dunning, J. Chem. Phys. 111, 7316 (1999) CrossRefGoogle Scholar
  32. J.-L. Le Garrec, D.A. Steinhurst, M.A. Smith, J. Chem. Phys. 114, 8831 (2001) CrossRefGoogle Scholar
  33. L. Suess, R. Parthasarathy, F.B. Dunning, J. Chem. Phys. 117, 11222 (2002); Y. Liu, L. Suess, F.B. Dunning, J. Chem. Phys. 122, 214313 (2005) CrossRefGoogle Scholar
  34. D. Klar, M.-W. Ruf, H. Hotop, Meas. Sci. Technol. 5, 1248 (1994) CrossRefGoogle Scholar
  35. A. Schramm, I.I. Fabrikant, J.M. Weber, E. Leber, M.-W. Ruf, H. Hotop, J. Phys. B 32, 2153 (1999) CrossRefGoogle Scholar
  36. J.M. Weber, E. Leber, M.-W. Ruf, H. Hotop, Eur. Phys. J. D 7, 587 (1999) Google Scholar
  37. I.D. Petrov, V.L. Sukhorukov, E. Leber, H. Hotop, Eur. Phys. J. D 10, 53 (2000) CrossRefGoogle Scholar
  38. A. Gopalan, E. Leber, J. Bömmels, S.P.H. Paul, M. Allegrini, M.-W. Ruf, H. Hotop, Eur. Phys. J. D 30, 163 (2004) CrossRefGoogle Scholar
  39. J. Bömmels, E. Leber, A. Gopalan, J.M. Weber, S. Barsotti, M.-W. Ruf, H. Hotop, Rev. Scient. Instrum. 72, 4098 (2001) CrossRefGoogle Scholar
  40. H. Hotop, D. Klar, J. Kreil, M.-W. Ruf, A. Schramm, J.M. Weber, in The Physics of Electronic and Atomic Collisions, edited by L.J. Dubé, J.B.A. Mitchell, J.W. McConkey, C.E. Brion, AIP Conf. Proc. No. 360 (AIP Press, Woodbury, NY, 1995), p. 267 Google Scholar
  41. D.R. Miller, in Atomic and Molecular Beam Methods, edited by G. Scoles (Oxford Univ. Press, New York, 1988), Chap. 2, p. 14ff Google Scholar
  42. U. Buck, private communication (2002) Google Scholar
  43. H.S.W. Massey, Negative Ions (Cambridge University Press, London, 1976) Google Scholar
  44. F.C. Fehsenfeld, J. Chem. Phys. 53, 2000 (1970) CrossRefGoogle Scholar
  45. T.M. Miller, A.E. Stevens, J.F. Paulson, X. Liu, J. Chem. Phys. 100, 8841 (1994) CrossRefGoogle Scholar
  46. E.C.M. Chen, L.-R. Shuie, E.D. D’sa, C.F. Batten, W.E. Wentworth, J. Chem. Phys. 88, 4711 (1988) CrossRefGoogle Scholar
  47. P. Spanel, S. Matejcik, D. Smith, J. Phys. B 28, 2941 (1995) Google Scholar
  48. A. Schramm, Dissertation, Fachbereich Physik, Univ. Kaiserslautern, Shaker Verlag (Aachen, 1998), ISBN 3-8265-3657-6 Google Scholar
  49. J.M. Weber, M.-W. Ruf, H. Hotop, Z. Phys. D 37, 351 (1996) CrossRefGoogle Scholar
  50. M. Braun, S. Marienfeld, M.-W. Ruf, H. Hotop, J. Phys. B (in preparation) Google Scholar
  51. T. Kraft, M.-W. Ruf, H. Hotop, in Electronic and Atomic Collisions, edited by W.R. MacGillivray, I.E. McCarthy, M.C. Standage (Bristol, Philadelphia, New York, 1992), p. 599 Google Scholar
  52. E.E. Ferguson, Int. J. Mass Spectr. Ion Proc. 19, 53 (1976) CrossRefGoogle Scholar
  53. Y. Wang, R.L. Champion, L.D. Doverspike, J.K. Olthoff, R.J. van Brunt, J. Chem. Phys. 91, 2254 (1989) CrossRefGoogle Scholar
  54. D. Klar, B. Mirbach, H.J. Korsch, M.-W. Ruf, H. Hotop, Z. Phys. D 31, 235 (1994) CrossRefGoogle Scholar
  55. D. Spence, G.J. Schulz, J. Chem. Phys. 58, 1800 (1973) CrossRefGoogle Scholar
  56. D. Smith, N.G. Adams, E. Alge, J. Phys. B 17, 461 (1984) CrossRefGoogle Scholar
  57. Z.L. Petrovic, R.W. Crompton, J. Phys. B 18, 2777 (1985) Google Scholar
  58. J.L. Le Garrec, O. Sidko, J.L. Queffelec, S. Hamon, J.B.A. Mitchell, B.R. Rowe, J. Chem. Phys. 107, 54 (1997) CrossRefGoogle Scholar
  59. I.I. Fabrikant, M. Allan, H. Hotop, Phys. Rev. A 71, 022712 (2005) CrossRefGoogle Scholar
  60. D. Field, N.C. Jones, J.-P. Ziesel, Phys. Rev. A 69, 052716 (2004) CrossRefGoogle Scholar
  61. J.P. Gauyacq, A. Herzenberg, J. Phys. B 17, 1155 (1984) Google Scholar
  62. F.B. Dunning, J. Phys. Chem. 91, 2244 (1987) CrossRefGoogle Scholar
  63. C.E. Klots, Chem. Phys. Lett. 38, 61 (1976) CrossRefGoogle Scholar
  64. D. Klar, Dissertation, Fachbereich, Univ. Kaiserslautern (1993), unpublished Google Scholar
  65. I.I. Fabrikant, private communication (2005) Google Scholar
  66. T. Kiang, R.N. Zare, J. Am. Chem. Soc. 102, 4024 (1980) CrossRefGoogle Scholar
  67. L.M. Babcock, G.E. Streit, J. Chem. Phys. 74, 5700 (1981) CrossRefGoogle Scholar
  68. C.L. Lugez, M.E. Jacox, R.A. King, H.F. Schaefer III, J. Chem. Phys. 108, 9639 (1998) Google Scholar
  69. B.L. Gutsev, R.J. Bartlett, Mol. Phys. 94, 121 (1998) CrossRefGoogle Scholar
  70. T. Andersen, H. Haugen, H. Hotop, J. Phys. Chem. Ref. Data 28, 1511 (1999) Google Scholar
  71. S.V.K. Kumar, Abstracts of Int. Symposium on Electron-Molecule Collisions and Swarms (EMS-03), p. 141, Pruhonice, Prague, Czech Republic (2003) Google Scholar
  72. R.K. Curran, J. Chem. Phys. 34, 1069 (1961) CrossRefGoogle Scholar
  73. W. Tsang, J.T. Herron, J. Chem. Phys. 96, 4272 (1992) CrossRefGoogle Scholar
  74. T.M. Miller, S.T. Arnold, A.A. Viggiano, Int. J. Mass Spectr. 227, 413 (2003) CrossRefGoogle Scholar

Copyright information

© EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005

Authors and Affiliations

  • M. Braun
    • 1
  • S. Barsotti
    • 1
  • S. Marienfeld
    • 1
  • E. Leber
    • 1
  • J. M. Weber
    • 1
  • M.-W. Ruf
    • 1
  • H. Hotop
    • 1
    Email author
  1. 1.Fachbereich Physik, Technische UniversitätKaiserslauternGermany

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