Ring electrode trap

Ion traps also have been combined with beams of radicals. For studying collisions between small neutral carbon molecules C (n = 1—3) and stored ions a special experimental setup has been developed. In this instrument ions are confined in a ring electrode trap (RET) at temperatures between 80 K and 600 K. There they interact with an effusive carbon beam, which is produced via high-temperature vaporization of a carbon rod. For the... 

Fig. 8 Second-generation ion trap machine from the Asmis group [134]. The ion trap in this case is a ring-electrode trap, and fragment mass analysis is performed in a time-of-ilight mass spectrinneler. Reproduced with permission from [134]. Copyright (2009) ACS...

Figure Bl.7.14. Schematic cross-sectional diagram of a quadnipole ion trap mass spectrometer. The distance between the two endcap electrodes is 2zq, while the radius of the ring electrode is (reproduced with pennission of Professor R March, Trent University, Peterborough, ON, Canada).

Fig. 3. Schematic diagram of an ion trap where A and B represent end cap electrodes, C the ring electrode, Tq the internal radius of C, and the internal...

The quadrupole ion-trap, usually referred to simply as the ion-trap, is a three-dimensional quadrupole. This type of analyser is shown schematically in Figure 3.5. It consists of a ring electrode with further electrodes, the end-cap electrodes, above and below this. In contrast to the quadrupole, described above, ions, after introduction into the ion-trap, follow a stable (but complex) trajectory, i.e. are trapped, until an RF voltage is applied to the ring electrode. Ions of a particular m/z then become unstable and are directed toward the detector. By varying the RF voltage in a systematic way, a complete mass spectrum may be obtained. 

A three-dimensional ion trap is formed by three electrodes, two end caps and a ring electrode in the linear ion trap different electrodes form each of the four edges (Figure 2.11). 

Fig. 17.9 Sketch of a typical setup for ion trap experiments on lasing microdroplets. The oscillating field between the inner and outer ring electrodes forms the trapping potential, and gravitational forces can he opposed by static electrical fields to move the droplet to the trap center with no micromotion...

In most commercial cylindrical ion trap instalments the end-cap electrodes are held at ground potential and usually only a RF potential is applied to the ring electrode. When the RF amplitude is set to a low, so-called storage voltage, all ions above a certain m/z are trapped. This voltage is usually chosen so the lowest trapped m/z is greater than those of water, air, and solvent ions (i.e., above 100 to 150 Th), depending on the nature of the measured species. 

By applying the supplementary RF voltage during injection (without scanning the RF voltage on the ring electrode) it is possible to prevent certain ions from being trapped. 

Fig. 11.10. Diagram illustrating the inner surfaces of the primary components of a Paul (3D) quadrupole ion trap. Ions generated by an external source are injected into the trap through an aperture in one of the end caps. Scan functions for isolating ions in the trap, exciting the mass selected ions to induce unimolecular dissociation, and ejecting ions from the trap (for detection) are implemented through the application of DC and RF voltages to the ring electrode.

The ion-trap mass spectrometer uses three electrodes to trap ions in a small volume. The mass analyzer consists of a ring electrode separating two hemispherical electrodes. A mass spectrum is obtained by changing the electrode voltages to eject the ions from the trap. The advantages of the ion-trap mass spectrometer include compact size and the ability to trap and accumulate ions thus increasing the signal-to-noise ratio of a measurement [534,535,551, 553]. 

Fig. 1.20 The quadrupole ion trap. A fundamental RF potential is applied onto the ring electrode to trap ions. The gray circles represent...

The ion trap is a device that utilizes ion path stability of ions for separating them by their m/z [53]. The quadrupole ion trap and the related quadrupole mass filter tvere invented by Paul and Steinwedel [57]. A quadrupole ion trap (QITor 3D-IT) mass spectrometer operates with a three-dimensional quadrupole field. The QIT is formed by three electrodes a ring electrode with a donut shape placed symmetrically between two end cap electrodes (Fig. 1.20). 

The principles behind an ion trap mass spectrometer are similar to those of the quadrupole mass filter, except that the quadrupole field is generated within a three-dimensional cell using a ring electrode and no filtering of the ions occurs. All of the steps involved in the generation and analysis of the ions take place within the cell, and in order to detect the ions they must be destabilized from their orbits, by altering the electric fields, so... 

Figure 22-15 Ion-trap mass spectrometer, (o) Mass analyzer consists of two end caps (left and right) and a central ring electrode, (b) Schematic diagram. [Courtesy Vartan Associates. Sunnyvale. CA.j...

In reactions involving gas evolution, the RRDE can be problematic in that bubbles may become trapped at the centre of the disc electrode. To obviate this, a rotating double ring electrode was suggested [34], The collection efficiency, N0, is given by eqn. (41) if we define... 

Traditional 3D quadrupole ion traps utilize three electrodes two end caps and a ring electrode. The end caps are usually at ground potential and a RF voltage is applied to the ring electrode to generate a quadmpole field to store ions. Helium gas is present in the trap at a pressure of 1 mtorr to cool the ions and improve... 

The ion trap is a 3D analog of the linear quadrupole. Two of the rods form the end-cap electrodes, whilst the other pair of rods is bent round to form the doughnut-shaped ring electrode (Fig. 12). 

A recent effort of this laboratory has resulted in the introduction of a hyperbolic Penning trap (3 p. The cell consists of two end caps and one ring electrode similar to the design of Byrne and Farago (51.) (see Figure 8). 

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