An electron bombardment ionization source

Abstract

The present invention relates to an electron bombardment ionization source. A filament fixing seat, a magnetic element, a first electronic baffle, an electronic grid component, an ion repeller, a first ionization chamber, and a focusing lens group are sequentially arranged along the axial direction of a sampling capillary; one end of the sampling capillary is used for sampling, and the other end of the sampling capillary is placed in the first ionization chamber; the first filament component and the first ionization chamber are axially installed, the first filament component is installed on the filament fixing seat, the first electronic baffle is installed on the first filament component, the magnetic element is installed close to the first filament fixing seat, and the electronic grid is installed on the grid seat. The present invention improves the ionization efficiency of the electron bombardment ionization source through structural design, and through the control of the electron bombardment ionization source, enables a single mass spectrometer to separate the components of a complex sample, abandons gas chromatography, and realizes real-time and reliable analysis system.

Description

Technical Field

[0001] The invention relates to the field of ionization technology, in particular to an electron bombardment ionization source. Background Art

[0002] A mass spectrometer is a scientific instrument for analyzing the composition of chemical substances. It works by ionizing the molecules of the substance to be tested through certain means, and then screening and measuring the ions through an ion optical system. A mass spectrometer usually consists of an injection system, an ion source, a mass analyzer, a detector, a vacuum system, and an electronic control system.

[0003] The ion source is a key component in the mass spectrometer. Its function is to ionize the gaseous sample molecules introduced by the injection system into ions. The ionization of sample molecules is the primary step in mass spectrometry analysis. The performance of the ion source has a significant impact on many indicators of the instrument. Whether the sample molecules can be effectively ionized will directly affect important indicators such as the type of detectable substances, detection limit and sensitivity. The electron impact ionization (EI) source is a widely used ion source. Its basic principle is that the filament emits electrons, the accelerating electric field accelerates the electrons, and the high-energy electrons bombard the molecules of the analyte to ionize the molecules of the analyte.

[0004] In recent years, with the development of industry, the real-time and accuracy requirements of online gas monitoring in process industries have become increasingly higher. Limited by the application technology, the analysis of gas components in traditional process industries generally adopts the method of pre-separation by gas chromatography system and then detection by electron bombardment ionization source mass spectrometry system. Due to the influence of gas chromatography system, although it can meet some requirements of process control, it also has obvious shortcomings, such as slow analysis speed, inability to be online in real time, and poor versatility.

[0005] The electron bombardment ionization source used in commercial gas chromatography-mass spectrometry has many defects, such as electrons entering the ionization chamber through a slit or a small hole, resulting in most electrons not entering the ionization chamber; the sample molecule introduction path is orthogonal to the electron introduction path, resulting in low electron utilization. These defects lead to low ionization efficiency of the electron bombardment ionization source, resulting in low sensitivity of the instrument. Summary of the invention

[0006] In order to achieve the above-mentioned purpose and other advantages according to the present invention, the purpose of the present invention is to provide an electron bombardment ionization source, comprising: a sampling capillary, a filament fixing seat, a magnetic element, a first electronic baffle, a first filament component, an electronic grid component, an ion repeller, a first ionization chamber, and a focusing lens group, wherein one end of the sampling capillary is used for sampling, and the other end of the sampling capillary is placed in the first ionization chamber; along the axial direction of the sampling capillary, the filament fixing seat, the magnetic element, the first electronic baffle, the electronic grid component, the ion repeller, the first ionization chamber, and the focusing lens group are arranged in sequence; the first filament component and the first ionization chamber are axially installed, the first filament component is installed on the filament fixing seat, the first electronic baffle is installed on the first filament component, the magnetic element is installed close to the first filament fixing seat, and the electronic grid is installed on the grid seat.

[0007] Furthermore, it also includes a second filament component and a second electronic baffle, wherein the second filament component is mounted on the filament fixing seat, and the second electronic baffle is mounted on the second filament component.

[0008] Furthermore, the first filament component and the second filament component both include a first filament electrode, a second filament electrode, a filament electrode ceramic sleeve, and a filament; the filament is installed between the first filament electrode and the second filament electrode, the filament electrode ceramic sleeve is installed on the first filament electrode, the first filament electrode and the second filament electrode are fixed on the filament fixing seat, the first electronic baffle and the second electronic baffle are both fixed on the second filament electrode and the filament electrode ceramic sleeve, and the filament is located between the corresponding electronic baffle and the electronic grid component.

[0009] Furthermore, the first electronic baffle and the second electronic baffle are both baffles with a bending angle.

[0010] Furthermore, the electronic grid component comprises an electronic grid and a grid seat, and the electronic grid is mounted on the grid seat.

[0011] Furthermore, it also includes a second ionization chamber, the first ionization chamber is communicated with the second ionization chamber, and the second ionization chamber is located between the first ionization chamber and the focusing lens group.

[0012] Furthermore, it also includes a heating ring, which is sleeved on the second ionization chamber.

[0013] Furthermore, the heating ring is a ceramic heating ring.

[0014] Furthermore, the focusing lens group includes an ion extraction lens, an ion focusing lens, and an ion ejection lens; along the ion emission direction, the second ionization chamber, the ion extraction lens, the ion focusing lens, and the ion ejection lens are arranged in sequence.

[0015] Furthermore, the filament fixing seat is a ceramic filament fixing seat.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention provides an electron bombardment ionization source, which improves the ionization efficiency of the electron bombardment ionization source through structural design, and controls the electron bombardment ionization source so that a single mass spectrometer can separate the components of a complex sample, discarding gas chromatography, and realizing a real-time and reliable analysis system.

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 It is a schematic diagram of the structure of an electron bombardment ionization source;

[0021] Figure 2 A cross-sectional view of the structure of an electron bombardment ionization source Figure 1 ;

[0022] Figure 3 A cross-sectional view of the structure of an electron bombardment ionization source Figure 2 ;

[0023] Figure 4 It is a schematic diagram of the filament components;

[0024] Figure 5 Schematic diagram of the electric field equipotential lines at the electron entrance;

[0025] Figure 6 Schematic diagram of the electron flow at the electron entrance Figure 1 ;

[0026] Figure 7 Schematic diagram of the electron flow at the electron entrance Figure 2 ;

[0027] Figure 8It is a schematic diagram of various mass spectrum peak overlap;

[0028] Fig. 9 Schematic diagram of spectrum signals of the same substance under different electron energies.

[0029] In the figure: 1. injection capillary; 2. filament fixing seat; 3. magnetic element; 4. first electronic baffle; 5. first filament component; 51. second filament electrode; 52. first filament electrode; 53. filament; 54. filament electrode ceramic sleeve; 6. electronic grid component; 7. ion repeller; 8. first ionization chamber; 9. second ionization chamber; 10. heating ring; 11. focusing lens group; 111. ion extraction lens; 112. ion focusing lens; 113. ion expulsion lens; 12. second filament component. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0031] In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention, and have no specific meanings. Therefore, "module", "component" or "unit" can be used in a mixed manner.

[0032] Example 1

[0033] An electron impact ionization source, such as Figure 1-Figure 3 As shown, it includes: a sampling capillary, a filament fixing seat, a magnetic element, a first electronic baffle, a first filament component, an electronic grid component, an ion repeller, a first ionization chamber, and a focusing lens group. One end of the sampling capillary is used for sampling, and the other end of the sampling capillary is placed in the first ionization chamber to introduce the substance to be tested into the ionization chamber for ionization; along the axial direction of the sampling capillary, the filament fixing seat, the magnetic element, the first electronic baffle, the electronic grid component, the ion repeller, the first ionization chamber, and the focusing lens group are arranged in sequence; the first filament component and the first ionization chamber are axially installed, and the first filament component is installed on the filament fixing seat. In this embodiment, the filament fixing seat is a ceramic filament fixing seat. The first electronic baffle is installed on the first filament component, and the first electronic baffle is used to provide an electric field to repel the electrons emitted by the filament into the ionization chamber; the magnetic element is installed close to the first filament fixing seat. In this embodiment, the magnetic element is a magnet, which is used to provide a magnetic field for the electron bombardment ionization source, so that the electrons spiral forward and increase the collision cross section between the electrons and the molecules of the substance to be tested. The electron grid is installed on the grid holder. The electron grid provides an electric field that can deflect electrons into the axis of the ionization chamber, so that the electrons are at the axis position when entering the ionization chamber, increasing the probability of collision between electrons and molecules.

[0034] In order to prevent the use of the device from being affected by damage to the first filament component, the present embodiment designs a dual filament structure so that the second filament can be started when one filament is damaged; preferably, it also includes a second filament component and a second electronic baffle, the second filament component is mounted on the filament fixing seat, and the second electronic baffle is mounted on the second filament component.

[0035] like Figure 4 As shown, the first filament component and the second filament component both include a first filament electrode, a second filament electrode, a filament electrode ceramic sleeve, and a filament. The filament is installed between the first filament electrode and the second filament electrode, the filament electrode ceramic sleeve is installed on the first filament electrode, the first filament electrode and the second filament electrode are fixed to the filament fixing seat, the first electronic baffle plate and the second electronic baffle plate are both fixed on the second filament electrode and the filament electrode ceramic sleeve, and the filament is located between the corresponding electronic baffle plate and the electronic grid component. The filament is used to emit electrons, and the two filaments are switched for use. When one of the filaments is working, the other filament is not working.

[0036] Furthermore, the first electronic baffle and the second electronic baffle are both baffles with a bending angle.

[0037] Furthermore, the electronic grid component includes an electronic grid and a grid seat, and the electronic grid is installed on the grid seat.

[0038] In order to achieve deep ionization of the molecules of the object to be detected, a second ionization chamber is further included, the first ionization chamber is connected to the second ionization chamber, and the second ionization chamber is located between the first ionization chamber and the focusing lens group. In the first ionization chamber, electrons are allowed to collide with the molecules of the object to be detected for ionization, and in the second ionization chamber, electrons are allowed to further collide with the unionized molecules of the object to be detected, so as to achieve deep ionization of the molecules of the object to be detected.

[0039] Furthermore, a heating ring is also included, and the heating ring is sleeved on the second ionization chamber. In this embodiment, the heating ring is a ceramic heating ring. The ceramic heating ring is sleeved on the outside of the second ionization chamber and is used to heat the entire ionization chamber. On the one hand, it prevents the liquefaction and deposition of the molecules of the object to be detected, ensuring the cleanliness and anti-pollution ability of the ion source, and on the other hand, it improves the activity of electrons and molecules of the object to be detected, ensuring high ionization efficiency.

[0040] like Figure 3As shown, the focusing lens group includes an ion extraction lens, an ion focusing lens, and an ion ejection lens; along the ion emission direction, the second ionization chamber, the ion extraction lens, the ion focusing lens, and the ion ejection lens are sequentially arranged. The ion extraction lens can extract the ionized ions from the ionization chamber on the one hand, and can reflect the electrons back on the other hand. The reflected electrons can collide with the unionized molecules of the object to be measured in the second ionization chamber for further ionization; the ion focusing lens is used to focus the ions extracted from the ionization chamber so that the ions can efficiently enter the subsequent ion optical system; the ion ejection lens is used to transfer the ions into the subsequent ion optical system.

[0041] The filaments of the electron bombardment ionization source of the present invention are axially mounted with the ionization chamber, but in order to make room for the sample injection capillary, the two filaments are not located on the central axis of the ionization chamber. The present invention utilizes the electric field formed by the electron baffle, the electron grid and the ion repeller. Figure 5 As shown, the electrons are deflected when entering the ionization chamber, so that the electrons enter the ionization chamber axially, as shown in FIG. Figure 6 , Figure 7 As shown. In the present invention, the electrons are introduced into the first ionization chamber axially, and the sample molecules are also introduced into the ionization chamber axially. Compared with the scheme in which the electron introduction direction and the sample molecule introduction direction are orthogonally distributed, the advantage of both being introduced axially is that the movement path of the electrons can be overlapped with the movement path of the molecules of the object to be detected, which fully ensures the collision between the electrons and the molecules of the object to be detected, so that the molecules of the object to be detected are fully ionized.

[0042] The present invention electrically connects an electronic baffle, a first filament, a second filament, an electronic grid, an ion repeller, a ceramic heating ring, an ion extraction lens, an ion focusing lens, and an ion ejection lens. The electric fields of the three components of the electronic baffle, the electronic grid, and the ion repeller guide the electrons to the central axis of the ionization chamber. Changing the voltage of the electronic baffle and the electronic grid can change the energy of the electrons entering the ionization chamber. When the pressure difference between the electronic baffle, the electronic grid, and the ion repeller becomes smaller, the energy of the electrons becomes smaller; the first ionization chamber and the second ionization chamber are grounded; the ion extraction lens, the ion focusing lens, and the ion ejection lens together form a focusing lens group to extract and focus the ions; the ion extraction lens applies a negative voltage to extract the ions and reflect the electrons, so that the electrons cannot escape from the ionization chamber, but are reflected back to the second ionization chamber to collide with the non-ionized gas molecules for deep ionization.

[0043] A method for operating an electron bombardment ionization source comprises:

[0044] At present, most electron bombardment ionization sources use 70eV electron energy to bombard sample molecules. In this case, if chromatographic separation is not performed, the spectra of multiple substances will overlap together, making it difficult to distinguish the amount of each substance. Figure 8 shown.

[0045] By adjusting the voltage of the electronic baffle and the electronic grid, the energy of the electrons entering the ionization chamber is different. Under different electron energies, the proportions of the various peaks in the spectrum formed by the same substance are different, such as Fig. 9 The present invention calculates the concentration ratio of each substance in the mixed substance through the spectrum peak ratio of single substance under different electron energies and the spectrum of the mixed substance under different energies.

[0046] For example: a mixture contains n substances with concentrations of x1, x2, ... n , the spectrum formed has five peaks a, b, c, d, and e. At 70 eV, the peak ratios of the spectrum formed by the mixed substances are a1, b1, c1, d1, and e1. According to the spectrum library, the peak ratio of the spectrum formed by the first substance at 70 eV is a 11 、b 11 、c 11 d 11 、e 11 , the spectrum peak ratio of the second substance at 70eV is a 12 、b 12 、c 12 d 12 、e 12 , and so on, the spectrum peak ratio formed by the nth substance at 70eV is a 1n 、b 1n 、c 1n d 1n 、e 1n . Through the above data, we can get the matrix equation:

[0047]

[0048] Among them, x1, x2, ... x n is the amount to be obtained; a 11 、b 11 、c 11 d 11 、e 11 、a 12 、b 12 、c 12 d 12 、e 12 ……a 1n 、b 1n 、c 1n d 1n 、e 1n The values ​​are those of the 70 eV standard spectrum library, which are known quantities; a1, b1, c1, d1, and e1 are the values ​​of the mixture measured at 70 eV, which are known quantities.

[0049] At the second electron energy, for example 60 eV, the peak ratios of the spectrum formed by the mixed substance are a2, b2, c2, d2, and e2. According to the spectrum library, the peak ratio of the spectrum formed by the first substance at 60 eV is a 21 、b 21 、c 21 d 21 、e 21 , the spectrum peak ratio of the second substance at 70eV is a 22 、b 22 、c 22 d 22 、e 22 , and so on, the spectrum peak ratio formed by the nth substance at 70eV is a 2n 、b 2n 、c 2n d 2n 、e 2n . Through the above data, we can get the matrix equation:

[0050]

[0051] By analogy, at the nth energy, we can get the matrix equation:

[0052]

[0053] Through the above n matrix equations, we can solve x1, x2...x n The value of can be used to calculate the ratio of the amount of each substance in the mixed substance. By adding automatic energy adjustment and automatic calculation to this method, the amount of each substance in the mixed substance can be quickly calculated.

[0054] The above are only embodiments of this specification and are not intended to limit one or more embodiments of this specification. For those skilled in the art, one or more embodiments of this specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of one or more embodiments of this specification shall be included in the scope of the claims of one or more embodiments of this specification. One or more embodiments of this specification One or more embodiments of this specification One or more embodiments of this specification One or more embodiments of this specification.

Claims

1. An electron bombardment ionization source, characterized in that: include: A sampling capillary, a filament fixing seat, a magnetic element, a first electronic baffle, a first filament component, an electronic grid component, an ion repeller, a first ionization chamber, and a focusing lens group, wherein one end of the sampling capillary is used for sampling, and the other end of the sampling capillary is placed in the first ionization chamber; along the axial direction of the sampling capillary, the filament fixing seat, the magnetic element, the first electronic baffle, the electronic grid component, the ion repeller, the first ionization chamber, and the focusing lens group are sequentially arranged; the first filament component and the first ionization chamber are axially mounted, the first filament component is mounted on the filament fixing seat, the first electronic baffle is mounted on the first filament component, the magnetic element is mounted close to the first filament fixing seat, and the electronic grid is mounted on the grid seat; It also includes a second filament component and a second electronic baffle, wherein the second filament component is mounted on the filament fixing seat, and the second electronic baffle is mounted on the second filament component; The electronic grid component comprises an electronic grid and a grid seat, and the electronic grid is installed on the grid seat.

2. An electron bombardment ionization source according to claim 1, characterized in that: The first filament component and the second filament component both include a first filament electrode, a second filament electrode, a filament electrode ceramic sleeve, and a filament. The filament is installed between the first filament electrode and the second filament electrode, the filament electrode ceramic sleeve is installed on the first filament electrode, the first filament electrode and the second filament electrode are fixed to the filament fixing seat, the first electronic baffle and the second electronic baffle are both fixed to the second filament electrode and the filament electrode ceramic sleeve, and the filament is located between the corresponding electronic baffle and the electronic grid component.

3. An electron bombardment ionization source according to claim 1, characterized in that: The first electronic baffle and the second electronic baffle are both baffles with a bending angle.

4. An electron bombardment ionization source according to claim 1, characterized in that: The invention also includes a second ionization chamber, wherein the first ionization chamber is communicated with the second ionization chamber, and the second ionization chamber is located between the first ionization chamber and the focusing lens group.

5. An electron bombardment ionization source according to claim 4, characterized in that: It also includes a heating ring, which is sleeved on the second ionization chamber.

6. An electron bombardment ionization source according to claim 5, characterized in that: The heating ring is a ceramic heating ring.

7. An electron bombardment ionization source according to claim 4, characterized in that: The focusing lens group includes an ion extraction lens, an ion focusing lens, and an ion ejection lens; along the ion emission direction, the second ionization chamber, the ion extraction lens, the ion focusing lens, and the ion ejection lens are arranged in sequence.

8. An electron bombardment ionization source according to claim 1, characterized in that: The filament fixing seat is a ceramic filament fixing seat.

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