Trapping electrode

Figure Bl.7.1. Schematic diagram of an electron ionization ion source source block (1) filament (2) trap electrode (3) repeller electrode (4) acceleration region (5) focusing lens (6).

Caravatti, R Allemann, M. The Infinity Cell a New Trapped-Ion Cell With Radiofrequency Covered Trapping Electrodes for FT-ICR-MS. Org. Mass Spectrom. 1991,26,514-518. 

Figure 5.6. Schematic of a hybrid LTQ-Orbitrap mass spectrometer (a) transfer octapole (b) curved rf-only quadmpole (C-trap) (c) gate electrode (d) trap electrode (e) ion optics (f) inner orbitrap electrode (g) outer orbitrap electrodes (Makarov et at., 2006a).

By expanding the circled region in Fig. 13, the ion-trap stability diagram (Fig. 14) plotted in terms of the parameters az and qz is obtained. These parameters are directly related to the RF (qz) and DC (az) voltages applied to the ion-trap electrodes. The areas of stability have boundaries where the (lu parameters (u — z or r) have values 0 and 1. fju is a complex function of au and qu and is directly related to the fundamental secular frequency of the ion (mu) and the main RF frequency (Q) by the equation... 

Figure 4. Exploded modified cubic trap with formed excitation/detection plates. Trap electrodes are segmented by electrically isolating a disk shaped region.

Mass analysis is based on mass selective instability. DC and RF voltages applied to the trap electrodes are such that ions over the entire m/e range of interest can be trapped within the field imposed by the electrodes. After this storage period, the parameters U and V0 are changed so that the trapped ions of consecutive values of m/e become... 

A substantial improvement was obtained when we separated spatially the detection of the spin direction from the place where spin Hips are induced. This was achieved by a transfer of the ion from the analysis trap to the precision trap. The potential minimum in which the ion was kept is moved by adiabatic change of the storage voltages at the trap electrodes. While in the analysis trap... 

Antiproton-matter annihilation at rest produces on average 3 charged pions with momenta around 300 MeV/c. These particles must first traverse the trap electrodes, the wall of the surrounding vacuum vessel, the walls of the inner dewar, and finally the walls of the enclosure of the detectors. Multiple scattering in these layers leads to an uncertainty of the annihilation vertex position of about 0.5 mm and the accuracy of the hit measurement in each of the two layers of the silicon strip detector should be matched to this extrapolation accuracy. 

Ion traps (March and Todd, 2005) have in themselves the possibility of performing all three stages of MS/MS experiment (precursor ion selection, its collision with a target gas, analysis of the product ions) in the same physical space limited by the three-ion trap electrodes (intermediate ring and two end caps). This will operate as a MS/MS in time device. This result is achieved by varying, in a sequential way, the potential applied on the electrodes. 

The linear ion trap analyser is a variation of the ion trap analyser introduced to combat some of the problems that had been encountered with the ion trap in relation to the space-charge effects. The Unear ion trap utilises two trapping electrode rings on the end of a quadrupole. This allows the instrument to be used in a normal scanning quadrupole mode it also allows for the end electrodes to be switched on to retain only specific ions in the trap for collision with the damping gas. 

FIGURE 9.9 (a) Cross-section of the quadrupole ion trap electrodes, (b) A picture of the... 

The ion trap used in the experiments and shown in Figure 10.2b has the following dimensions Tq = 3.50 mm, Zq = 2.70 mm, Zendcap = 20.00 mm, andR = 4.00 mm these values have been chosen in order to achieve a nearly perfect radial quadrupole RF field [19] and a near-harmonic DC-axial potential over a few millimeters. Numerical simulations show that these choices of ion-trap dimensions result in ti = 0.248. The applied RF field is coupled resonantly to the ion-trap electrodes at a radial frequency... 

Theoretically, in a pure quadrupole ion trap, the RF electric field increases linearly in radial and axial directions. The axial and radial direction motions of ions are decoupled in such a pure quadrupole ion trap. In reality, it is impossible to create a pure quadrupole ion trap due to the finite sizes of the trap electrodes and orifices in the electrodes. 

The Finnigan ITD-800, that was introduced subsequently, had a separate high temperature vacuum enclosure that contained the ion trap electrodes. The reduction of water and air contamination in the vacuum chamber reduced the Cl content of the mass spectra to a negligible level. However, the use of early XT personal... 

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