Miniaturized ion traps

Article By:

Pau, Stanley College of Optical Sciences, The University of Arizona, Tucson, Arizona.

Slusher, Richart E. Quantum Institute, Georgia Institute of Technology, Atlanta, Georgia.

Last reviewed:2009

DOI:https://doi.org/10.1036/1097-8542.YB090039

The quadrupole ion trap is an instrument designed to store and separate charged particles using a combination of radio-frequency (RF) and direct-current (dc) electric fields. The ion trap has many important applications in biology, geology, physics, and chemistry, particularly in the areas of mass spectrometry, precision atomic and molecular spectroscopy, and quantum information science. Two ion-trap geometries are commonly used: the Paul trap, which uses a three-dimensional quadrupole field, and the linear trap, which uses a two-dimensional quadrupole field (Fig. 1). Depending on the operating conditions, a charged particle can form either a stable or an unstable trajectory inside such a quadrupole potential. By varying the operating voltages, frequency, and ambient pressure, it is possible to trap ions and particles with a large range of mass-to-charge ratios in a controlled environment over a period of days. The mass-to-charge ratio is a dimensionless ratio between the mass number of an ion and its charge number, and has been demonstrated to fall in the range 10²–10⁹, using a single Paul trap with a 1-mm radius.

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