Determination of Ion Frequencies in a Quadrupole Ion Trap By Using a Fast Direct Current Pulse as Pump and a Laser Probe

  • Stephen A. Lammert
  • Curtis D. Cleven
  • R. Graham Cooks
Articles

Abstract

A new technique has been developed which allows the direct measurement of frequencies of ions trapped in a quadrupole ion trap mass spectrometer. This pump/probe method employs a fast direct current (DC) pulse (pump) to displace a kinetically cooled ion population from the center of the trap, and a laser (probe) which recognizes when ions reappear at the center of the trap by the formation of photodissociation fragments. The translationally excited ions undergo periodic motion within the confines of the ion trap, and this periodic motion can be followed by recording the intensity of the photodissociation fragment as a function of the delay time between the DC pump and the laser probe. The DC pulse has a rise time of 15 ns; data are taken 1 ms after its application to allow stable ion motion to be sampled. Sampling of the ion cloud is done at 50 ns intervals, and fast Fourier transformation of the time-based data yields the ion frequencies and their relative magnitudes. Data are reported for ions derived from acetophenone (m/z 105) and 1,4-cyclohexadiene (m/z 80) under various trapping conditions corresponding to different Mathieu qz values. The measured fundamental secular frequencies, fz and fr, are found to agree well with those predicted. The presence of higher order multipole contributions to the trapping field is evident from such ion frequencies as the drive frequency, fRF,. The ability to measure ion frequencies under operating conditions provides a new tool for comparing simulated and experimental data. Simulation data from the program ITSIM, modified to account for the effects of collisions, are shown to predict the major frequency components observed in the experimental data.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    March, R. E.; Hughes, R. J. Qundrupole Storage Mass Spectrometry; Wiley: New York, 1989.Google Scholar
  2. 2.
    Fulford, J. E.; Hoa, D.-N.; Hughes, R. J.; March, R. E.; Bonner, R. F.; Wong, G. J. J. Vac. Sci. Technol. 1980, 17, 829.CrossRefGoogle Scholar
  3. 3.
    Kaiser, R. E., Jr.; Louris, J. N.; Amy, J. W.; Cooks, R. C. Rapid Commun. Mass Spectrom. 1989, 3, 225.CrossRefGoogle Scholar
  4. 4.
    Kaiser, R. E., Jr.; Cooks, R. G.; Syka, J. E. P.; Stafford, G. C. Rapid Commun. Mass Spectrom. 1990, 4, 30.CrossRefGoogle Scholar
  5. 5.
    Major, F. G.; Dehmelt, H. G. Phys. Rev. 1968, 170, 91.CrossRefGoogle Scholar
  6. 6.
    Brincourt, G.; Catella, R.; Zerega, Y.; André, J. Chem. Phys. Lett. 1990, 174, 626.CrossRefGoogle Scholar
  7. 7.
    Vedel, F. Int. J. Mass Spectrom. Ion Processes 1991, 108, R11.CrossRefGoogle Scholar
  8. 8.
    Vedel, F. Int. J. Mass Spectrom. Ion Processes 1991, 106, 33.CrossRefGoogle Scholar
  9. 9.
    Bate, D. J.; Dholakia, K.; Thompson, R. C.; Wilson, D. C. J, Mod. Optics 1992, 39, 305.CrossRefGoogle Scholar
  10. 10.
    Imajo, H.; Urabe, S.; Hayasaka, K.; Watanabe, M. J. Mod. Optics 1992, 39, 317.CrossRefGoogle Scholar
  11. 11.
    Eades, D. M.; Johnson, J. V.; Yost, R. A. Proceedings of the 41st Annual ASMS Conference on Mass Spectrometry and Allied Topics: San Francisco, May 30-June 4, 1993; WP 163.Google Scholar
  12. 12.
    Todd, J. F. J.; Penman, A. D.; Thomer, D. A.; Smith, R. D. Rapid Commun. Mass Spectrom. 1990, 4, 108.CrossRefGoogle Scholar
  13. 13.
    Morand, K. L., Ph. D. Thesis, Purdue University, December 1992.Google Scholar
  14. 14.
    Hemberger, P. H.; Nogar, N. S.; Williams, J. D.; Cooks, R. G.; Syka, J. E. P. Chem. Phys. Lett. 1992, 191, 405.CrossRefGoogle Scholar
  15. 15.
    Williams, J. D.; Cooks, R. G.; Syka, J. E. P.; Hemberger, P. H.; Nogar, N. S. J. Am. Soc. Mass Spectrom. 1993, in press.Google Scholar
  16. 16.
    Louris, J. N.; Cooks, R. G.; Syka, J. E. P.; Kelley, P. E.; Stafford, G. C.; Todd, J. F. J. Anal. Chem. 1987, 59, 1677.CrossRefGoogle Scholar
  17. 17.
    Lammert, S. A.; Cooks, R. G. J. Am. Soc. Mass Spectrom. 1991, 2, 487.CrossRefGoogle Scholar
  18. 18.
    Stafford, G. C.; Kelley, P. E.; Syka, J. E. P.; Reynolds, W. E.; Todd, J. F. J. Int. J. Mass Spectrom. Ion Processes 1984, 60, 85.CrossRefGoogle Scholar
  19. 19. (a)
    Wang, Y.; Franzen, J. Int. J. Mass Spectrum. Ion Processes 1993, in press. (b) Compare Franzen, J., submitted, Wang, Y., Rapid Commun. Mass Spectrom., in press.(c) Franzen, J., Wang, Y., Int. J.Mass Spectrom. Ion. Processes 1991, 106, 63.Google Scholar
  20. 20.
    Louris, J, N.; Stafford, G. C., Jr.; Syka, J. E. P.; Taylor, D. Proceedings of the 40th Annual ASMS Conference on Mass Spectrometry and Allied Topics; Washington DC, May 31-June 5, 1992; p 1003.Google Scholar
  21. 21.
    Reiser, H.-P.; Julian, R. K., Jr.; Cooks, R.G. Int. J. Mass Spectrom. Ion Processes 1992, 121, 49.CrossRefGoogle Scholar
  22. 22.
    Jlian, R. K., Jr.; Cooks, R. G. J. Am. Soc. Mass Spectrom. submitted for publication.Google Scholar
  23. 23.
    Eades, D.M.; Yost, R.A. Rapid Commun. Mass Spectrom. 1992, 6, 573.CrossRefGoogle Scholar
  24. 24.
    Louris, J. N.; Cooks, R. G.; Syka, J. E. P.; Kelley, P. E.; Stafford, G. C., Jr.; Todd, J. F. J. Anal. Chem. 1987, 59, 1677.CrossRefGoogle Scholar

Copyright information

© American Society for Mass Spectrometry 1994

Authors and Affiliations

  • Stephen A. Lammert
    • 2
  • Curtis D. Cleven
    • 2
  • R. Graham Cooks
    • 2
  1. 1.Oak Ridge National LaboratoryOak Ridge
  2. 2.Department of ChemistryPurdue UniversityWest Lafayette

Personalised recommendations