Applied Physics B

, Volume 114, Issue 1–2, pp 75–80 | Cite as

Experiments with an ion-neutral hybrid trap: cold charge-exchange collisions

  • W. W. SmithEmail author
  • D. S. Goodman
  • I. Sivarajah
  • J. E. Wells
  • S. Banerjee
  • R. Côté
  • H. H. Michels
  • J. A. MongtomeryJr.
  • F. A. Narducci


Due to their large trap depths (∼1 eV or 10,000 K), versatility, and ease of construction, Paul traps have important uses in high-resolution spectroscopy, plasma physics, and precision measurements of fundamental constants. An ion-neutral hybrid trap consisting of two separate but spatially concentric traps [a magneto-optic trap (MOT) for the neutral species and a mass-selective linear Paul trap for the ionic species] is an ideal apparatus for sympathetic cooling. However, over the past few years, hybrid traps have proven most useful in measuring elastic and charge-exchange rate constants of ion-neutral collisions over a wide temperature range from kilo-Kelvin to nano-Kelvin. We report some initially surprising results from a hybrid trap system in our laboratory where we have loaded the Paul trap with Ca+ ions in the presence of a Na MOT (localized dense gas of cold Na atoms). We find a strong loss of Ca+ ions with MOT exposure, attributed to an exothermic, non-resonant ion-neutral charge-exchange process with an activation barrier, which leads to the formation of Na+ ions. We propose a detailed mechanism for this process. We obtain an estimated measure of the rate constant for this charge exchange of ∼2 × 10−11  cm3/s, much less than the Langevin rate, which suggests that the Langevin assumption of unit efficiency in the reaction region is not correct in this case.


Charge Exchange Entrance Channel Paul Trap Effective Core Potential Trapping Time 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



W.S. acknowledges support for the experiments from the National Science Foundation (NSF) under Grant No. PHY0855570. The work of S.B. was supported in part by the U.S. Department of Energy, Office of Basic Energy Sciences, and the work of R.C. by NSF Grant No. PHY-1101254.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • W. W. Smith
    • 1
    Email author
  • D. S. Goodman
    • 1
  • I. Sivarajah
    • 1
  • J. E. Wells
    • 1
  • S. Banerjee
    • 1
    • 2
  • R. Côté
    • 1
  • H. H. Michels
    • 1
  • J. A. MongtomeryJr.
    • 1
  • F. A. Narducci
    • 3
  1. 1.Department of Physics (U-3046)University of ConnecticutStorrsUSA
  2. 2.Department of ChemistryYale UniversityNew HavenUSA
  3. 3.EO Sensors DivisionNaval Air Systems CommandPatuxent RiverUSA

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