Runaway Mobilities of Ions in Helium

  • F. Howorka


The term “runaway mobility” of ions in a buffer gas like helium refers to a non-equilibrium condition: it is impossible for the ions to attain a defined drift velocity in an applied field, they are rather accelerated all the time. In contrast the usual mobility concept demands the condition of equilibrium where every momentum gain in the field is compensated by an average momentum loss over a long time. Microscopically the ions — even in the case of a well-established equilibrium — never have a constant speed: only on the average over many ions the whole group has a mean drift velocity and a certain velocity distribution. Mobility is defined as the ratio of the mean velocity attained in the buffer gas under a certain field strenght and the value of the field strenght. It is usually found to be a function of the reduced field strength E/N, where E is the field strength as measured in vcm-1 (or vm-1) and N is the gas number density in cm-3 (or m-3). The unit is Townsends (1 Towns-end = 10-17v m2 or 10-21V m2; its symbol is Td).


Drift Velocity Drift Tube Momentum Transfer Cross Section Apparent Mobility Runaway Effect 
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  1. 1.
    Lin, S.L., Gatland, I.R. and Mason, E.A.: Mobility and Diffusion of Protons and Deuterons in Helium — a Runaway Effect. J. Phys. B: Atom. Molec. Phys. 12, 4179–88 (1979)CrossRefADSGoogle Scholar
  2. 2.
    Kolos, W. and Peek, J.M: New ab initio Potential Curve and Quasibound States of HeH+. Chem. Phys. 12, 381–6 (1976)CrossRefADSGoogle Scholar
  3. 3.
    Viehland, L.A. and Mason, E.A.: Gaseous Ion Mobility in Electric Fields of Abitrary Strength. Ann. Phys., NY. 91, 499–533 (1975)CrossRefADSGoogle Scholar
  4. 4.
    Howorka, F., Fehsenfeld, F.C., Albritton, D.L.: H+ and D+ Ions in He: Observations of a Runaway Mobility. J. Phys. B12, 4189–4197 (1979)ADSGoogle Scholar
  5. 5.
    Moruzzi, J.L., Kondo, Y.: The Mobility of H+ Ions in Helium. Jap. J. Appl. Phys. 19, 1411–1412 (1980)CrossRefADSGoogle Scholar
  6. 6.
    Waldman, M., Mason, E.A.: to be publ. (1983)Google Scholar
  7. 7.
    Mason, E.A., Waldman, M.: Theory of Ion Transport in Gases — Runaway Ions. Electron and ion swarms, ed. by L.G. Christoporou, Pergamon press, pp. 147–156 (1981)Google Scholar
  8. 8.
    Viehland, L.A., Mason, E.A., and Lin, S.L.: Test of the Interaction Potentials of h - and Br- Ions with He Atoms and of Cl- Ions with Ar Atoms. Phys. Rev. A24, 3004–9 (1981)ADSGoogle Scholar
  9. 9.
    Mc Farland, M., Albritton, D.L., Fehsenfeld, F.C., Ferguson, E.E. and Schmeltekopf, A.L.: Flow-Drift Technique for Ion Mobility and Ion-Molecule Reaction Rate Constant Measurements. J. Chem. Phys. 59, 6610–9, 6620–8 (1973)Google Scholar
  10. 10.
    Ellis, H.W., Pai, R.Y., Mc Daniel, E.W., Mason, E.A. and Viehland, L.A.: Transport Properties of Gaseous Ions Over a Wide Energy Range, I. Atom. Data Nucl. Data Tables 17, 177–210 (1976)CrossRefADSGoogle Scholar
  11. 11.
    Adams, N.G. and Smith, D.: The Selected Ion Flow Tube (SIFT): a Technique for Studying Ion-Neutral Reactions. Int. J. Mass Spectrom. Ion Phys. 21, 349–59 (1976)CrossRefGoogle Scholar
  12. 12.
    Smith, D. and Adams, N.G.: Gas Phase Ion Chemistry, ed. M.T. Bowers (New York: Academic), pp. 1–44 (1979)Google Scholar
  13. 13.
    Ellis, H.W., Mc Daniel, E.W., Albritton, D.L., Viehland L.A., Lin, S.L. and Mason, E.A.: Transport Properties of Gaseous Ions over a Wide Energy Range, II. Atom. Data Nucl. Data Tables 22, 179–217 (1978)CrossRefGoogle Scholar
  14. 14.
    Lindinger, W and Albritton, D.L.: Mobilities of Various Mass-Identified Positive Ions in Helium and Argon. J. Chem. Phys. 62, 3517–22 (1975)CrossRefADSGoogle Scholar
  15. 15.
    Gatland, I.R.: Case Studies in Atomic Physics vol. 4, ed. E.W. Mc Daniel and M.R.C. Mc Dowell (Amsterdam: North Holland), pp. 369–437 (1974)Google Scholar
  16. 16.
    Mc Daniel, E.W. and Mason, E.A.: The Mobility and Diffusion of Ions in Gases (New York: Wiley) (1973)Google Scholar
  17. 17.
    Dobler, W., Lindinger, W., Howorka, F.: Kinetic Energy Dependences of the Branching Ratios of the Reactions He+, Ne+ and Ar+ H2O. 3rd Symp. on Atomic and Surface Physics; ed. W. Lindinger, Innsbruck, pp. 299–303 (1982)Google Scholar
  18. 18.
    Viehland, L.A.; Interaction Potentials for Li+ - Rare Gas Systems. Chem. Phys. 78, 279–294 (1983)CrossRefADSGoogle Scholar
  19. 19.
    Skullerud, H.R.: Calculation of Ion Drift and Diffusion: Basis Set Expansions with Non-Gaussian Weight Functions. Proc. 3rd Int. Swarm Seminar, W. Lindinger (ed.), Innsbruck, pp. 212–217 (1983)Google Scholar
  20. 20.
    Stefansson, T.: Diffusion of Lithium Ions in Argon. Proc. 3rd Int. Swarm Seminar. W. Lindinger (ed.), Innsbruck, pp. 227–233 (1983)Google Scholar

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© Springer-Verlag/Wien 1984

Authors and Affiliations

  • F. Howorka
    • 1
  1. 1.Institut für ExperimentalphysikUniversität InnsbruckInnsbruckAustria

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