Ion trap theory

The first commercial ion trap mass spectrometers were introduced in the early 1980s. Since the introduction, ion traps have become one of the most popular types of mass analyzers due to sensitivity, MS" capabilities, relatively inexpensive price, and compact size. The details of ion trap theory are covered in a number of references (Nourse and Cooks, 1990 March, 1997, 1998, 2000b) and only the general details will be given here. 

There are detailed accounts by Dawson and Whetten [4] and by Dawson [5] of the early development of quadrupole devices a full account of ion trap theory by March et al. [6] reviews by Todd [7], Cooks et al. [8], Glish and McLuckey [9], and March [10] and three volumes entitled Practical Aspects of Ion Trap Mass Spectrometry [11] that contain accounts from 30 laboratories en gaged in ion trap research. 

Limited quadrupole ion trap theory is presented here, but a thorough coverage of the QIT can be found in March and Hughes," in a three-volume book edited by March and Todd," and in a book by March and Todd on QIT which includes a brief chapter on the LQIL" ... 

R. E. March. Quadrupole Ion Trap Mass Spectrometry Theory, Simulation, Recent Developments and Applications. Rapid Commun. Mass Spectrom., 12(1998) 1543-1554. 

The quadrupole ion trap traps ions in an electric field generally in the presence of a buffer gas (He). The theory and some of its uses have been discussed by March (26). Ion molecule reactions in ion traps have been reviewed (27). The quadrupole ion trap is a relatively new instrument commercialized <20 years ago and the new generation of instruments has only been available since 1995. Thus gas-phase inorganic chemistry using a quadrupole ion trap is as yet relatively hard to find, but on the increase. 

March, R. E. (1998). Quadrupole ion trap mass spectrometry Theory, simulation, recent development and applications. Rapid Commun. Mass Spectom. 12 1543-1554. 

Abstract. Absolute measurements of the energies of helium-like vanadium resonances on an electron beam ion trap (EBIT) axe reported. The results agree with recent theoretical calculations and the experimental precision (27-MO ppm) lies at the same level as the current uncertainty in theory (0.1 eV). The measurements represent a 5.7%-8% determination of the quantum electrodynamics (QED) contribution to the transition energies and are the most precise measurements of the helium-hke resonances in the Z = 19—31 range. These are the first precision X-ray measurements on the National Institute of Standards and Technology EBIT and strongly commend the EBIT as a new spectroscopic source for QED investigations. 

The quadrupole ion trap (QJT) is about the size of a small fist and consists of a ring electrode and two hyperbolic end electrodes (see March and Todd68 for a detailed theory of operation and history of development). Like the linear ion trap (LIT, see below), the QJT operates at relatively high pressure (10 3 torr) with a helium buffer gas that assists the ions to maintain a stable orbital frequency. The buffer gas also serves as the collision gas for collision-induced dissociation (CID) during MS/MS experiments. 

Catalytic CO Oxidation by Free Au2. The potential catal3dic activity of Au2 in the CO combustion reaction was first predicted by Hakkinen and Land-man [382]. The subsequent experimental investigation employing an rf-ion trap indeed revealed the catalytic reaction of the gold dimer and, in conjunction with theory, a detailed reaction cycle could be formulated [33]. Also for particular larger gold cluster anions evidence for catalytic CO2 formation has... 

J. Kiibler Theory of itinerant electron magnetism 105. Y. Kuramoto, Y. Kitaoka Dynamics of heavy electrons 104. D. Bardin, G. Passarino The Standard Model in the making 103. G.C. Branco, L. Lavoura, J.P. Silva CP Violation 102. T.C. Choy Effective medium theory 101. H. Araki Mathematical theory of quantum fields 100. L. M. Pismen Vortices in nonlinear fields 99. L. Mestel Stellar magnetism 98. K. H. Bennemann Nonlinear optics in metals 96. M. Brambilla Kinetic theory of plasma waves 94. S. Chikazumi Physics of ferromagnetism 91. R. A. Bertlmann Anomalies in quantum field theory 90. P. K. Gosh Ion traps... 

March, R.E. Londry, F.A. Theory of quadrupole mass spectrometry. In Practical Aspects of Ion Trap Mass Spectrometry, eds. R.E. March and J.F.J. Todd, Vol. 1, Chapter 2, pp. 25 8. CRC Press, Boca Raton, 1995. 

See also Volume 4, Ch ter 4 Rectangular Waveform Driven Digital Ion Trap (DIT) Mass Spectrometer Theory and Applications by Francesco Brancia. 

Volume rv is entitled Theory and Instrumentation and is composed of six parts Fundamentals, New Ion Trapping Techniques, Fourier Transform Mass Spectrometry, Quadrupole Rod Sets, 3D-Quadrupole Ion Trap Mass Spectrometry, and Photochemistry of Trapped Ions. 

An early account (Dawson 1976) of the bridge between the subsequent developments of the device by physicists (who refer to the device as the Paul Trap ) and chemists (who have used several names, most often simply ion trap but sometimes quadrupole ion storage trap, QUISTOR , 3D trap and, in one commercially available form, ion trap mass spectrometer ), was followed by extensive reviews written by and for chemists (e.g., Todd 1991 March 1992) and a three-volume set (March 1995) covering theory, practicalities and applications. More recently an excellent first introduction for chemists (March 1997) was updated (March 1998) and followed by a comprehensive treatise on the subject (March 2005). An interesting personal perspective by one of the leading contributors to the field (Stafford 2002) describes the additional problems faced in producing a commercial instrument. 

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