JPH03190049A - Rydberg atom impact type ion source - Google Patents

Abstract

PURPOSE:To produce Rydberg atoms stably and produce negative ions in a sample in a long-time stable state by forming a grid at a Rydberg atom production section of an ion source block in a needle shape. CONSTITUTION:Thermoelectrons emitted from a filament 5 are collected by a grid 6 in a needle shape which is positively charged and rare gas led from a rare gas lead entrance 1 collides with accelerated thermoelectrons in the vicinity of the grid 6 to produce Rydberg atoms. By forming the grid 6 into a needle shape in this way, a space between the grid 6 and the filament 5 is enlarged to eliminate discharge phenomenon and also the thermoelectrons emitted from the filament 5 can be smoothly moved to the grid 6 and trapped, so that the Rydberg atoms can stably produced and negative ions in a sample can produced in a long-time stable state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an ion source for a mass spectrometer that negatively ionizes a sample by colliding sample molecules with Rydpel atoms and performs mass spectrometry. More specifically, the present invention relates to an ion source that can stably generate Rydberg atoms and allow negative ions in a sample generated by collision with Rydberg atoms to exist in a stable state.

(Conventional technology) In recent years, trace amounts of bioactive substances, biological components, fragrances, and more! l! Ultra-trace amounts of chemicals with large molecular weights and coarse structures, such as super-active substances such as qi, pharmaceuticals such as vitamins, a wide range of food additives, and antioxidants for fats and oils,
There is a growing need for simple and highly sensitive analysis.

Mass spectrometry is the simplest and most economical method for analyzing these substances quickly and with high sensitivity.

Mass spectrometry requires the sample to be ionized. Therefore, a gaseous sample of a molecular compound is generally ionized by an electron beam (for example, 70V) or a proton or ion beam. In this method, cations are 10' times more likely to be produced than anions, and the energy imparted to the sample molecules by the electron beam is much greater than that required for ionization or bond cleavage. For this reason, fragmentation or fragmentation occurs after ionization, and secondary ion-molecule reactions of fragments occur, making the resulting spectrum complex and missing information about the parent molecule, which is particularly important for analyzing analytical results. It tends to be certain.

In addition, for low energy and soft ionization,
Various methods have been developed, such as field desorption ionization and high-speed atom impact ionization. However, even with these methods, as the molecular weight of the sample increases, sample decomposition and secondary ionization processes become more likely to occur, requiring complex analysis of decomposed ions.

On the other hand, in order to solve these problems, a method has also been developed in which gaseous sample molecules collide with Rydberg atoms, the sample is ionized, and the ions are analyzed by pawn shops. However, in the conventional method of mass spectrometry of ions generated by colliding gaseous sample molecules with Rydberg atoms, as shown in Figure 3, the distance between the filament and the mesh grid is short, so the atoms sputtered from the filament ( The problem is that tungsten atoms (for example, tungsten atoms) are deposited on the mesh grid and discharged. When the discharge phenomenon occurs repeatedly, the production of negative noons in the sample by Rydberg atoms is interrupted each time, and sometimes the filament is broken. Also,
Thermionic electrons generated in the filament are accelerated and collided with a rare gas (e.g. xenon) to generate Rydberg atoms, but because the concentration of thermionic electrons that gather around the wire mesh grid is low, the concentration of the Rydberg atoms generated is also low, and the spread is reduced. In this case, not only the efficiency of generating negative ions of the parent molecule of the sample by the Ryudoperi atoms decreases, but also it becomes impossible to stably collect data.

(Problems to be Solved by the Invention) The present invention solves the above problems, stably generates Rydberg atoms, and allows negative ions in a sample generated by the collisions of Rydberg atoms to exist in a stabilized state. The purpose of this study is to provide a Rydberg atom bombardment ion source that enables

(Means for solving the fll! problem) In other words, the present invention provides an ion source for a mass spectrometer that collides gaseous sample molecules with Rydberg atoms to ionize the sample and perform mass analysis. The present invention relates to an ion source characterized in that the atom generating section has a grid needle bar shape.

According to the present invention, the grid of the Rydberg atom bombardment ion source block is a needle-bar type grid, thereby eliminating the discharge caused by the deposition of atoms sputtered from the filament, and further reducing the concentration of thermionic electrons around the grid. Therefore, the concentration of Rydberg atoms produced can be increased, and the negative ionization efficiency of the sample is improved.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the Rydberg impact type ion source block according to the present invention. The ion source block is made up of two chambers, with two grids (7) and (8) installed in the middle. Thermionic electrons emitted from the filament (5) are collected by a needle bar-shaped grid (8) to which a positive voltage is applied. grid (7)
and (8) are both applied negatively to prevent thermionic electrons from flowing into the sample ionization chamber (4).The rare gas (e.g. xenon) introduced from the 3° rare gas inlet (1) is (6) Collisions with nearby accelerated thermoelectrons to generate Ryudoperi atoms. The rheudoperi atoms collide with the gaseous sample introduced from the sample inlet (2) in the sample ionization chamber (4) to negatively ionize the sample molecules.

FIG. 3 is a sectional view showing the configuration of a conventional ion source block. In the conventional method, the grid (5') is shaped like a wire mesh, so when atoms emitted from the filament are deposited on the wire mesh, a discharge occurs between the filament (5') and the grid (0).In contrast, in the present invention, By making the grid (6) into a needle bar shape, the grid (8) and filament (5)
The space of fll is expanded, the discharge phenomenon is eliminated, and furthermore, it becomes possible to smoothly move the thermoelectrons emitted from the filament to the grid (6) and trap them.

Suitable materials for the needle bar-shaped grid of the present invention include stainless steel, tantalum, molybdenum, tungsten, or nickel, or alloys containing 2211 or more of these elements.

The diameter of the needle bar can be set appropriately, but it is usually 0.1 to 10s+
, preferably 6.2 to 5 Sui.

(Effects of the Invention) According to the present invention, it is possible to suppress the discharge phenomenon that was a drawback of the conventional method, and also to stably generate Rydberg atoms, which in turn allows negative ions in the sample to be generated in a stable state for a long time. I can do it.

Further, the ion source can be miniaturized and can be attached to a normal commercially available mass spectrometer, so it has high versatility.

(Example) A total ion chromatogram of benzotriazole was measured using a mass spectrometer equipped with the Rydberg atom bombardment ion source of the present invention shown in FIG. The analysis conditions are as follows.

Gu! J9 F (Gi) = 100V Grid (G2): -100V Grid (G): -300V Filament current near, 5A Chamber: 1oov Further, the needle bar was made of stainless steel and had a diameter of 2 m.

The results are shown in Figure 4. On the other hand, similar measurements were performed under the same conditions using a conventional mass spectrometer equipped with the ion source shown in FIG. The results are shown in FIG. As is clear from Figure 4, the amount of negative ions generated by the present invention is at a high level and is very stable, whereas the total ion chromatogram of Figure 5 by the conventional method shows that the generation of negative ions is unstable. This clearly shows that the amount of negative ions decreases by m each time due to repeated and frequent discharges.

[Brief explanation of drawings]

FIG. 1 is a sectional view of one embodiment of the structure of the Rydberg atomic bombardment ion source block of the present invention, and FIG. 2 is a front view of this ion source block. FIG. 3 is a sectional view showing the configuration of a conventional ion source block. Figures 4 and 5 show total ion chromatograms of benzotriazole. 1.1'...Rare gas inlet 2.2'...Sample inlet 3.3'...Rydberg atom generation chamber 4.4'
...Sample ionization chamber 5.5'...Filament 6.6'...Grid 7.7 with positive applied voltage
′...Grid 8′ applied to the negative...
−・Glyph 9′ applied to the minus chamber

Claims (1)

[Claims] In an ion source for a mass spectrometer that collides gaseous sample molecules with Rydberg atoms to ionize the sample and perform mass spectrometry, Rydberg atomic bombardment is characterized in that the grid of the Rydberg atom generator of the ion source block is shaped like a needle bar. type ion source.