Paul traps development

Another approach to mass analysis is based on stable ion trajectories in quadnipole fields. The two most prominent members of this family of mass spectrometers are the quadnipole mass filter and the quadnipole ion trap. Quadnipole mass filters are one of the most connnon mass spectrometers, being extensively used as detectors in analytical instnunents, especially gas clnomatographs. The quadnipole ion trap (which also goes by the name quadnipole ion store, QUISTOR , Paul trap, or just ion trap) is fairly new to the physical chemistry laboratory. Its early development was due to its use as an inexpensive alternative to tandem magnetic sector and quadnipole filter instnunents for analytical analysis. It has, however, staned to be used more in die chemical physics and physical chemistry domains, and so it will be described in some detail in this section. 

H. G. Dehmelt (University of Washington, Seattle) and W. Paul (Bonn) development of the ion trap technique. 

Principle. The cylindrical quadrupole ion trap is based on the same principle as the quadrupole mass filter, but the geometry is different (Fig. 2.16). The cylindrical QIT, or Paul trap, was developed almost simultaneously with the quadrupole mass filter [232, 233]. Recently, a variant of the theme has emerged, the linear quadrupole ion trap [236], which is a device built like a quadrupole mass filter with extra trapping end electrodes for the axial direction. Under stable conditions, ions moving around inside such traps will ideally continue to do that forever. 

The most direct approach to the geometric structures of molecules and also of clusters in the gas phase are diffraction methods, in particular the diffraction of an electron beam. Since an adequate cluster flux for such electron diffraction experiments has been so far only possible, if the full source output beam was sampled, the uncertainties in cluster size (no mass-selection) and internal energy prevent an unambiguous interpretation of electron diffraction patterns [138-145]. In a new development, a technique has been recently reported that relies upon an rf-Paul trap [146] to take advantage of the current... 

The Paul trap, popularly known as a quadrupole ion trap (QIT), was introduced in 1958 by Paul and colleagues [33]. This contribution was recognized by the award of the 1989 Nobel Prize for Physics to Wolfgang Paul. Because it is a three-dimensional analog of a quadrupole mass filter, it is also called a three-dimensional ion trap to distinguish it from the two-dimensional ion trap described in Section 3.7. The QIT became popular as a mass spectrometer after development of the mass-selective instability mode of mass analysis by Stafford and co-workers [34]. For further reading, several review articles [35-41] and books are cited at the end of the chapter. 

In 1989 the Nobel Prize in physics was shared by Wolfgang Paul (for development of the three-dimensional quadrupole ion trap as an extension of the linear quadrupole mass filter) and Hans Dehmelt (for spectroscopic studies of ions suspended in ion traps of various kinds, including the Paul trap) the Nobel award lectures (Paul 1990 Dehmelt 1990) incidentally also provide accounts of their work that are interesting historically and also lucid and accessible to nonexperts. Other early work on development of the same general principles for ion trapping (Good 1953 Wuerker 1959) should also be... 

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. 

Wolfgang Paul 1989, Physics Development of quadruplole and quadrupole ion trap... 

By Earnshaw s theorem, it is impossible to make a trap for ions static electric fields, but Penning in 1936 developed a stable ion trap that was a combination of a static uniform magnetic field and inhomogeneous electrostatic fields. In 1958 Paul and his associates made a successful electric quadrupole ion trap without a magnetic field by having the electric field oscillate sinusoidally at radio frequencies. 

The ICP/MS is an elemental and isotopic analysis method that was first developed in the early 1980s. The ICP had been used only as a source for emission spectroscopy until it was adapted for producing ions for a mass analyzer (Douglas and French, 1981 Houk et al., 1980 Houk et al., 1981 Houk and Thompson, 1982). Since 1983, several manufacturers have sold ICP/MS instruments that incorporate various mass analyzer systems, such as quadrupole mass filter, magnetic sector field, time-of-flight, Paul ion trap, and ion detection systems such as the electron... 

Mass spectrometry has earned a number of Nobel Prizes, starting with Joseph J. Thompson, who received the physics prize in 1906 for the development of positive rays. Next, the chanistry award went to Francis W. Aston, in 1922, for his research elucidating the existence of isotopes. Moving to the modem era, Wolfgang Paul and Hans G. Demelt were cited in 1989 for developing ways to trap ions (physics), while John B. Fenn and Koichi Tanaka received the chemistry prize, in 2002, for the development and application of ESI and MALDI, respectively, to the analysis of proteins. 

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