JP2860495B2 - Resonance cell - Google Patents

Description

The present invention relates to a resonance cell used in a Fourier transform ion cyclotron resonance spectrometer (hereinafter, referred to as FT-ICR), and more particularly to a recombination reaction of ions having different charges. The present invention relates to a resonance cell suitable for use in the present invention.

<Prior Art> Ions in a uniform magnetic field make a spiral motion in the direction of the magnetic field. Projecting this motion on a plane perpendicular to the magnetic field results in a circular motion. Here, assuming that the charge of the ion is q, the mass of the ion is m, and the strength of the magnetic field is B, the rotation frequency fc is fc = qB / 2πm. As is clear from this equation, by measuring the rotation frequency fc and the magnetic field strength B, the mass-to-charge ratio of the ion is obtained.
m / q is required.

Based on this principle, FT-ICR analyzers trap ions in a vacuum using an electrostatic field and a static magnetic field, and forcibly apply ions to the trapped ions by applying an AC voltage at the cyclotron resonance frequency for a certain period of time. The mass spectrometry of the ions is performed by detecting the excited and accelerated ions and analyzing the frequency of the periodic motion.

FIG. 4 is a configuration diagram of a resonance cell conventionally used for generating and detecting ions in an FT-ICR analyzer.
The excitation electrodes 1a, 1b and the detection electrodes 3a, 3b are each formed into a rectangular arc so as to be used as an excitation electrode pair and a detection electrode pair. This constitutes a mold detection unit A.
The trap electrodes 5a and 5b are formed in a circular shape, and are arranged so as to cover both ends of a cylindrical detection unit A formed by the excitation electrodes 1a and 1b and the detection electrodes 3a and 3b. Note that these trap electrodes
Through holes 7 and 8 are provided in the center of 5a and 5b. Filament 9, grid 10 and accelerating electrode 11 are trap electrodes 5a
An electron gun B that outputs an electron beam toward the through-hole 7 is formed. The electron beam output from the electron gun B passes through the through hole 8 of the trap electrode 5b and enters the collector 12.

The ions generated and caught in the cylindrical detection section A configured as described above rotate and move at the speed of thermal energy, and the radius of rotation is small, and the phase varies for each ion and it is difficult to detect the ions as they are. is there. Therefore, an AC voltage having a cyclotron resonance frequency is applied to the excitation electrodes 1a and 1b balanced with the magnetic field to forcibly accelerate the ions. As a result, the phases of the ions are aligned, the speed increases, and the radius of rotation increases. Then, the accelerated ions are detected by the detection electrodes 3a and 3b parallel to the magnetic field.

<Problems to be Solved by the Invention> However, such a conventional resonance cell has only one ion source, and cannot measure an ion-ion reaction process.

The present invention has been made by focusing on such points.
FT that can measure the ion-ion reaction process
An object of the present invention is to provide a resonance cell for an ICR analyzer.

<Means for Solving the Problem> The configuration of the present invention for solving the above problem is to apply an AC electric field having a cyclotron resonance frequency to ions trapped in a vacuum by an electrostatic field and a static magnetic field for a certain period of time. A resonance cell of a Fourier transform ion cyclotron resonance spectrometer for performing mass analysis of ions by forcibly exciting ions, detecting accelerated ions, and performing frequency analysis of the periodic motion thereof. A plurality of the resonance cells are arranged in series so that the degree of vacuum between the resonance cells is the same, at least the trap electrodes of the opposed resonance cells are formed in a mesh shape, and the potential of each resonance cell can be changed to positive or negative. Thus, the charged particles (ions and electrons) can move between the respective resonance cells.

<Operation> By using two resonance cells to trap and resonate different ions and controlling the potential of the trap electrodes provided at both ends of the cell, generated ions can be moved to each other.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a structural explanatory view showing one embodiment of the present invention, and the same reference numerals are given to parts common to FIG. 4, and re-explanation thereof will be omitted. In the figure, A is the first cell, B is the second cell, and the trap electrodes are formed in a mesh. The cylindrical part formed by the excitation electrodes 1a to 1d and the detection electrodes 3a to 3d has a diameter of 40 mm,
It is about 50mm long. Between cells is a counter trap electrode (5b, 5c) to approximately 2mm intervals of about, these 10 ^-8 the To
It is arranged in a vacuum vessel of about rr.

In this configuration, the filament and the grid on the second cell B side are removed, and the collector 12 is arranged on the Z axis so as to face the trap electrode of the second cell.

The operation of the resonance cell having the above configuration will be described with reference to FIG. FIG. 2 shows an ICR time domain signal when SF ₆ (sulfur hexafluoride) is used as a sample. The potentials of the trap electrodes 5a and 5b of the first cell A are both set to a negative voltage of about -10 V, and the potentials of the trap electrodes 5c and 5d of the second cell B are both set to a positive voltage of about +10 V. Simultaneously ionize by impact, excite and accelerate generated ions,
FIG. 9 is an output waveform diagram of an oscilloscope showing a result detected at a sampling rate of 2 MHz.

As is clear from the figure, the output from the second cell B has a uniform amplitude, whereas the amplitude of the first cell A is not uniform, and there are two frequency components. This means that the first cell A
And indicates that the generated SF ₅ ⁺ in the second cell B ^- and SF ₅ ^- SF ₆ in.

FIG. 3 is a diagram showing a state of movement of ions when the trap potential is displaced, and FIG. 3 (A) is a simplified cross-sectional view in the XZ plane of the resonance cell. (B) shows a state of trapping the ions produced in each cell, by the first cell to the negative of about -10V together trap electrodes example B ^- ions, the second cell trapping electrode A ⁺ ions are trapped, for example, by making both positive about + 10V.

Next, as shown in (c), the potentials of the cells 5b and 5c are set to the ground level while the potentials of the cells outside each cell are maintained.
As a result, the ions B ⁻ and A ⁺ move and react to the adjacent cells along the potential curve.

Next, as shown in (d), the potentials of all the trap electrodes are set to + 10V. Thereby, A ⁺ ions are trapped in each cell. In this state, the amount of A ⁺ ions in the first and second cells is measured by exciting and detecting ions in the same manner as in the conventional resonance cell, and the amount of attenuation from the state of (b) is evaluated. By doing so, it is possible to measure the recombination coefficient and the like. Such a series of sequences can be easily realized by a programmable pulse sequence or the like.

Although FIG. 3 shows an example of a positive ion-negative ion reaction process, the present invention can also be applied to a positive ion-electron reaction process. -Applicable to the reaction process of negative ions.

Further, in the present embodiment, the number of cells is shown as two, but the number of cells is not limited to this embodiment and can be increased as needed.

<Effects of the Invention> As described above in detail with the embodiments, according to the present invention, it is possible to realize a resonance cell for a Fourier transform ion cyclotron resonance analyzer capable of performing an experiment of an ion-ion reaction process. Can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an output waveform from each cell by an oscilloscope, and FIG. 3 is a diagram showing a movement state of ions due to a change in trap potential in FIG. FIG. 4 is a configuration diagram of a conventional resonance cell. 1a to 1d: Excitation electrode, 3a, 3d: Detection electrode, 5a to 5d: Trap electrode, 9: Filament, 10: Grid, 11 ...
Acceleration electrode, 12 ... Collector.

Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01J 49/00-49/48

Claims (1)

(57) [Claims] An ion is forcibly excited by trapping ions in a vacuum by an electrostatic field and a static magnetic field, and applying an AC electric field having a cyclotron resonance frequency to the trapped ions for a predetermined time to detect accelerated ions. A Fourier transform ion cyclotron resonance spectrometer for performing mass analysis of ions by performing a frequency analysis of the periodic motion, wherein a plurality of the resonance cells are arranged in series and a vacuum between the resonance cells is provided. The degree of charge is the same, at least the trap electrodes facing each other between the resonance cells are formed in a mesh shape, and the polarity of the potential of each trap electrode in each resonance cell can be changed, so that the charged particles can move between the resonance cells. A resonance cell which is movable with respect to each other.