Review of Scientific Instruments
Feedback | Help | Exit
Review of Scientific Instruments
Search:
   
 
 
 
Previous Article
Fluorescence lifetime sensor of copper ions in water
We demonstrate an optical method for the selective detection of Cu(II) ions in water using time-resolved fluorescence resonance energy transfer from the dye rhodamine 800 encapsulated in a sensor. In ...
Next Article
Crossed-beams arrangement for the investigation of charge-changing collisions between multiply charged ions
A crossed-beams experiment designed to study charge-changing collisions between singly charged ions has been modified to extend its applicability to collisions between multiply charged ions in a broad...

Apparatus for measuring electron-impact excitation cross sections using fast metastable atoms produced via charge exchange

Rev. Sci. Instrum. 67, 2738 (1996); doi:10.1063/1.1147102

Issue Date: August 1996

You are not logged in to this journal. Log in

John B. Boffard, Mark E. Lagus, L. W. Anderson, and Chun C. Lin
Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706
An apparatus for measuring absolute cross sections due to electron-impact excitation out of the metastable levels of rare-gas atoms via the optical method is described with the focus specifically on excitation out of the 2 3S metastable helium level. The metastable helium target (He*) is prepared by charge exchange between 1.6 keV He+ ions and cesium vapor. An electron beam crosses the fast metastable beam target at a right angle and the fluorescence is collected at right angles to both beams. The charge transfer reaction produces He atoms mainly in the n=2 He levels. Because the target contains a negligible ground state He fraction, we can measure excitation cross sections from excitation threshold up to an arbitrarily high energy (keV regime) which represents a major improvement over previous metastable excitation cross sections measurements. The He* target density is extremely small (~106 atoms/cm3) yielding minuscule signal rates. We describe steps taken to maximize the signal-to-noise ratio. We discuss the implications of using a fast beam target including both the finite flight time of the excited atoms across the light gathering region and the reduction of the cascade contributions to the apparent cross sections. A discussion of the identification and elimination of various systematic effects is also given. To measure absolute cross sections, we explicitly determine the spatial distributions of both the electron and metastable beams, as well as the spatially dependent response of the fluorescence gathering region. We determine the absolute flux of fast metastable atoms using a thermal detector calibrated with a He+ ion beam. As examples, we present absolute cross sections for excitation out of the 2 3S metastable level into the 3 3D and 4 3D levels. ©1996 American Institute of Physics.
History: Received 1 March 1996; accepted 26 April 1996
Permalink: http://link.aip.org/link/?RSINAK/67/2738/1
BUY THIS ARTICLE   (US$24)
Download PDF (255 kB) View Cart

KEYWORDS and PACS

Keywords
PACS
  • 39.90.+d
    Instrumentation and techniques for atomic and molecular physics Other instrumentation and techniques for atomic and molecular physics
  • 34.50.Fa
    Atomic and molecular collision processes and interactions Scattering of atoms, molecules, and ions Electronic excitation and ionization of atoms (including beamfoil excitation and ionization)
  • YEAR: 1996

RELATED DATABASES


To view database links for this article,
you need to log in.
To view database links for this article,
you need to log in.

PUBLICATION DATA

ISSN:
0034-6748 (print)   1089-7623 (online)
Publisher:
AIP is a member of CrossRef AIP

REFERENCES (27)
View in Separate Window/Tab
For access to fully linked references, you need to log in. For access to fully linked references, you need to Log in.
  1. A. R. Filippelli, C. C. Lin, L. W. Anderson, and J. W. McConkey, Adv. At. Mol. Opt. Phys. 33, 1 (1994).
  2. D. W. O. Heddle and J. W. Gallagher, Rev. Mod. Phys. 61, 221 (1989).
  3. A. J. Dixon, M. F. A. Harrison, and A. C. H. Smith, J. Phys. B 9, 2617 (1976).
  4. S. Trajmar and J. C. Nickel, Adv. At. Mol. Opt. Phys. 30, 45 (1992).
  5. C. C. Lin and L. W. Anderson, Adv. At. Mol. Opt. Phys. 29, 1 (1991).
  6. R. B. Lockwood, F. A. Sharpton, L. W. Anderson, and C. C. Lin, Phys. Lett. A 166, 357 (1992).
  7. R. B. Lockwood, L. W. Anderson, and C. C. Lin, Z. Phys. D 24, 155 (1992).
  8. D. L. A. Rall, F. A. Sharpton, M. B. Schulman, L. W. Anderson, J. E. Lawler, and C. C. Lin, Phys. Rev. Lett. 62, 2253 (1989).
  9. R. M. St. John, F. L. Miller, and C. C. Lin, Phys. Rev. 134, A888 (1964).
  10. A. S. Schlacter, D. H. Loyd, P. J. Bjorkholm, L. W. Anderson, and W. Haeberli, Phys. Rev. 174, 201 (1968).
  11. C. Reynaud, J. Pommier, Vu Ngoc Tuan, and M. Barat, Phys. Rev. Lett. 43, 579 (1979).
  12. V. Sidis, C. Kubach, and J. Pommier, Phys. Rev. A 23, 119 (1981).
  13. R. H. Neynaber and G. D. Magnuson, J. Chem. Phys. 65, 5239 (1976).
  14. Preliminary absolute results have been reported by M. E. Lagus, J. B. Boffard, L. W. Anderson, and C. C. Lin at the 48th Annual Gaseous Electronics Conference, paper DB-12, Berkeley, CA, October 10–13, 1995.
  15. J. H. Billen and H. T. Richards, Bull. Am. Phys. Soc. 25, 745 (1980).
  16. M. E. Lagus, J. B. Boffard, L. W. Anderson, and C. C. Lin, Phys. Rev. A 53, 1505 (1996).
  17. A. Viehl, M. Kanyo, A. van der Hart, and J. Schelten, Rev. Sci. Instrum. 64, 732 (1993).
  18. M. E. Lagus, Ph.D. thesis, University of Wisconsin-Madison, 1995.
  19. See, for example, J. M. Lafferty, J. Appl. Phys. 22, 299 (1951).
  20. J. O. Phelps and C. C. Lin, Phys. Rev. A 24, 1299 (1981).
  21. W. H. Kohl, Handbook of Materials and Techniques for Vacuum Devices (Reinhold, New York, 1967), p. 563.
  22. C. E. Kuyatt, in Methods of Experimental Physics, edited by B. Bederson and W. L. Fite (Academic, New York, 1968), Vol. 7-A.
  23. This method was applied byH. R. Moustafa Moussa, F. J. De Heer, and J. Schutten, Physica 40, 517 (1969), to cross sections of electron excitation out of the ground level of helium.
  24. E. A. Enemark and A. Gallagher, Phys. Rev. A 6, 192 (1972).
  25. We have extrapolated to higher energies the values ofL. A. Vainshtein et al., found in Table XXXVII ofB. L. Moiseiwitsch and S. J. Smith, Rev. Mod. Phys. 40, 238 (1968).
  26. W. L. Wiese, M. W. Smith, and B. M. Miles, Atomic Transition Probabilities, Natl. Stand. Ref. Data Ser. Natl. Bur. Stand. No. 22 (U.S. GPO, Washington, DC, 1969), Vol. II.
  27. G. A. Piech (private communication).

CITING ARTICLES
For access to citing articles, you need to log in.
For access to citing articles, you need to Log in.


Copyright © American Institute of Physics