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Virtually all Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry experiments are based on ion confinement in a Penning trap: namely, a spatially homogeneous static magnetic field B, and a three-dimensional axial (along B) quadrupolar electrostatic trapping potential. In addition, it is desirable to provide an alternating azimuthal (i.e. in a plane perpendicular to B) spatially uniform...
The motion of single ions through a perfect quadrupole is governed by linear differential equations in both static (d.c. only) and radio-frequency cases. However, motion in distorted quadrupole fields and higher multipoles (e.g. hexapoles, octapoles etc.) is determined by non-linear differential equations with coupled (x, y) terms in Cartesian coordinates. In imperfect quadrupoles with electrodes...
The use of multi-electrode structures as mass analysers is now very widespread. These devices are employed as partial pressure analysers, mass filters and ion traps. The first of these devices to utilise an electric quadrupole field for separating ions according to their mass-to-charge ratio was introduced in the 1950s. The operation of these devices is based on the nature of particle trajectories...
A thermal ionization source for mass spectrometry has been designed and tested. The ion source is based on a tungsten crucible with a deep cavity into which the sample is loaded. The crucible is heated by high energy electron bombardment from a tantalum filament surrounding the crucible. As the sample evaporates inside the crucible, gaseous analyte atoms are produced which interact with the inner...
Azimuthal quadrupolar excitation has become one of the most useful techniques for ion axialization and translational cooling for FT-ICR mass spectrometry, leading to order(s)-of-magnitude improvement in mass selectivity, resolving power, mass accuracy, remeasurement efficiency, etc. Recently, Hendrickson et al. (J. Am. Soc. Mass Spectrom. 6 (1995) 448-452) showed that axialization may be achieved...
The decay amplitude envelope of an ICR time-domain signal determines its corresponding Fourier transform mass spectral line shape. The commonly accepted FT-ICR frequency-domain unapodized Lorentzian spectral line shape originates from the Langevin ion-neutral collision model, in which an ion is treated as a point charge that induces an electric dipole moment in a neutral collision partner. The Langevin...
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