A pre-stage system of an electron ionization mass spectrometer

Abstract

The present invention belongs to the field of mass spectrometry analysis, and particularly relates to a pre-stage system of an electron ionization type mass spectrometer, aiming to solve the problems of low ionization efficiency and sample dissipation faced by traditional mass spectrometers in the analysis of gaseous compounds. The present invention includes a four-way pipe fitting, a first cold trap, a molecular beam collimator, a second cold trap, and a permanent magnet assembly. A plurality of fixed seats are provided on the four-way pipe fitting, and the four-way pipe fitting is fixedly connected to the frame of the mass spectrometer. The first cold trap and the molecular beam collimator are fixedly arranged on one side of the four-way pipe fitting, the second cold trap is arranged on the other side of the four-way pipe fitting, the first cold trap is connected to the second cold trap, and the permanent magnet assembly is fixedly connected to the four-way pipe fitting, significantly improving the recovery efficiency of non-ionized samples and solving the problems of low ionization efficiency, sample dissipation, vacuum degree reduction, and equipment corrosion faced by traditional mass spectrometers in the analysis of this gaseous compound.

Description

Technical Field

[0001] The present invention belongs to the field of mass spectrometry analysis, and particularly relates to a pre-stage system of an electron ionization mass spectrometer. Background Art

[0002] An electron ionization mass spectrometer is an important scientific analysis tool. Through the ionization process, a sample is converted into ions, and then through the deflection of the mass analysis system, ions with different mass-to-charge ratios are respectively incident on the corresponding Faraday cups, thereby measuring information such as the chemical bond structure and isotope abundance of compounds.

[0003] In the field of physical chemistry technology, some gaseous compounds are widely used in isotope enrichment and other affiliated industries. Mass spectrometers are often used for the analysis and detection of some highly volatile gaseous compounds. The products formed by the reaction of some highly volatile gaseous compounds with water in the air are highly corrosive and highly toxic. Moreover, the ionization efficiency of ionization mass spectrometers is generally low, and some materials to be analyzed escape in the mass spectrometry system, resulting in a decrease in vacuum degree and equipment corrosion. In addition, un-ionized molecules cannot be effectively recovered, affecting the accuracy of analysis results. In addition, the radioactivity and toxicity of gaseous compounds increase the complexity of equipment maintenance operations and safety risks for workers, and also pose a potential threat to the environment. Summary of the Invention

[0004] In order to solve the problems of low ionization efficiency and sample escape faced by traditional mass spectrometers in the analysis of gaseous compounds in the prior art, the present invention provides a pre-stage system of an electron ionization mass spectrometer, including a four-way pipe fitting, a first cold trap, a molecular beam collimator, a second cold trap, and a permanent magnet assembly:

[0005] A plurality of fixed seats are arranged on the four-way pipe fitting, the four-way pipe fitting is fixedly connected to the frame of the mass spectrometer, the first cold trap and the molecular beam collimator are fixedly arranged on one side of the four-way pipe fitting, the second cold trap is arranged on the other side of the four-way pipe fitting, the first cold trap is connected to the second cold trap, and the permanent magnet assembly is fixedly connected to the four-way pipe fitting;

[0006] Wherein, the first cold trap and the second cold trap can capture un-ionized samples.

[0007] According to a pre-stage system of an electron ionization mass spectrometer provided by some embodiments of the present application, the four-way pipe fitting includes a four-way pipe fitting fixed base;

[0008] The four-way pipe fitting is fixedly connected to the frame of the mass spectrometer through the four-way pipe fitting fixed base.

[0009] According to a pre-stage system of an electron ionization mass spectrometer provided by some embodiments of the present application, the first cold trap includes a first liquid nitrogen storage inner tank, a first cold trap fixed seat, and a sample recovery tank;

[0010] The first cold trap is fixedly connected to the four-way pipe fitting through the first cold trap fixing seat. One side of the first liquid nitrogen storage inner container is provided with a liquid nitrogen filling port, and the other side of the first liquid nitrogen storage inner container is provided with the sample recovery groove. The first liquid nitrogen storage inner container extends to the sample recovery groove, and the sample recovery groove is arranged close to the ionization chamber. A first cold trap connection port is further arranged outside the first liquid nitrogen storage inner container.

[0011] According to a pre-stage system of an electron ionization type mass spectrometer provided by some embodiments of the present application, the second cold trap includes a second liquid nitrogen storage inner container, a second cold trap connection port, a second cold trap fixing seat, a sample recovery plate, and a connection port corrugated pipe;

[0012] One side of the second liquid nitrogen storage inner container is provided with a liquid nitrogen injection port, and the other side of the second liquid nitrogen storage inner container is provided with the second cold trap fixing seat. The second liquid nitrogen storage inner container extends to the sample recovery plate, and the sample recovery plate is arranged close to the sample recovery groove. A second cold trap connection port adapted to the first cold trap connection port is further arranged outside the second liquid nitrogen storage inner container, and a connection port corrugated pipe is arranged on the second cold trap connection port.

[0013] According to a pre-stage system of an electron ionization type mass spectrometer provided by some embodiments of the present application, the molecular beam collimator includes a fixed base, a molecular beam outlet, and a sample injection pipe;

[0014] The molecular beam collimator is fixedly connected to the four-way pipe fitting through the fixed base. The molecular beam outlet is arranged on one side close to the four-way pipe fitting, and the sample injection pipe is arranged outside the fixed base.

[0015] According to a pre-stage system of an electron ionization type mass spectrometer provided by some embodiments of the present application, the permanent magnet assembly includes a conical permanent magnet and a magnet fixing seat;

[0016] The conical permanent magnet is fixedly connected to the four-way pipe fitting through the magnet fixing seat.

[0017] According to a pre-stage system of an electron ionization type mass spectrometer provided by some embodiments of the present application, a magnet with a magnetic pole opposite to that of the conical section of the conical permanent magnet is arranged in the four-way pipe fitting to form a magnetic line of force between the ionization chambers.

[0018] According to a pre-stage system of an electron ionization type mass spectrometer provided by some embodiments of the present application, the molecular beam collimator is formed by pressing multiple layers of gold foil.

[0019] Advantages of the present invention:

[0020] The first cold trap and the second cold trap adopt a double-spherical cold trap design, significantly improving the recovery efficiency of non-ionized samples. In conjunction with an efficient vacuum management system, it enables faster vacuum pumping and agile vacuum feedback, ensuring the stable operation of the system.

[0021] The molecular beam collimator can ensure that gas compound molecules enter the ionization chamber uniformly, enhancing the ionization efficiency and data accuracy. These core components are reasonably arranged through four-way pipe fittings, achieving compact integration, reducing vacuum leakage, simplifying installation and maintenance, and further improving the reliability of the equipment.

[0022] It not only effectively reduces environmental pollution and the health risks of operators but also provides higher precision, safety, and operability in physical and chemical technical analysis. Description of the Drawings

[0023] Other features, objectives, and advantages of this application will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0024] Figure 1 It is a structural diagram of the front-stage system of an ionization type mass spectrometer according to some embodiments of this application;

[0025] Figure 2 It is a structural diagram of a four-way pipe fitting according to some embodiments of this application;

[0026] Figure 3 It is a structural diagram of the first cold trap according to some embodiments of this application;

[0027] Figure 4 It is a structural diagram of the molecular beam collimator according to some embodiments of this application;

[0028] Figure 5 It is a structural diagram of the second cold trap according to some embodiments of this application;

[0029] Figure 6 It is a structural diagram of a conical permanent magnet according to some embodiments of this application.

[0030] In the figure: 1. Four-way pipe fitting; 101. Fixed connection base of the first cold trap; 102. Series connection port of mechanical pump and molecular pump; 103. Fixed connection base of high-power ion pump; 104. Fixed connection base of conical permanent magnet; 105. Fixed connection base of ionization system; 106. Fixed connection base of cold cathode vacuum gauge; 107. Fixed base of four-way pipe fitting; 2. First cold trap; 201. Liquid nitrogen filling port; 202. First liquid nitrogen storage inner tank; 203. Connection port of the first cold trap; 204. Fixed base of the first cold trap; 205. Sample recovery tank; 3. Molecular beam collimator; 301. Fixed base; 302. Molecular beam outlet; 303. Sample injection pipe; 4. Second cold trap; 401. Liquid nitrogen injection port; 402. Second liquid nitrogen storage inner tank; 403. Connection port of the second cold trap; 404. Fixed base of the second cold trap; 405. Sample recovery plate; 406. Connection port bellows; 5. Permanent magnet assembly; 501. Conical permanent magnet; 502. Magnet fixed base. Detailed implementation mode

[0031] The present application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, rather than limiting the invention. Additionally, it should be noted that for the convenience of description, only the parts related to the invention are shown in the drawings.

[0032] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and embodiments.

[0033] As Figures 1-6 shown, the present invention provides a pre-stage system of an electron ionization type mass spectrometer, including a four-way pipe fitting 1, a first cold trap 2, a molecular beam collimator 3, a second cold trap 4, and a permanent magnet assembly 5:

[0034] A plurality of fixed bases are provided on the four-way pipe fitting 1. The four-way pipe fitting 1 is fixedly connected to the frame of the mass spectrometer. The first cold trap 2 and the molecular beam collimator 3 are fixedly arranged on one side of the four-way pipe fitting 1. The second cold trap 4 is arranged on the other side of the four-way pipe fitting 1. The first cold trap 2 is connected to the second cold trap 4, and the permanent magnet assembly 5 is fixedly connected to the four-way pipe fitting 1;

[0035] Among them, the first cold trap 2 and the second cold trap 4 can capture the un-ionized samples.

[0036] In specific implementation, the four-way pipe fitting 1 can serve as the installation foundation for other devices. The body of the four-way pipe fitting 1 can be installed on the frame of the mass spectrometer, and then each functional component is sequentially installed to the corresponding connection interface. The first cold trap 2 is the left cold trap, and the second cold trap 4 is the right cold trap. The two cold traps are integrated together to capture the un-ionized samples, which can protect the stability of the vacuum environment and extend the operation life of the equipment. By setting the permanent magnet assembly 5, this configuration forms magnetic field lines with uniform intensity and high concentration between the ionization chambers, significantly enhancing the magnetic field environment inside the ionization chambers, improving the ionization efficiency and the stability of ion generation, and reducing the sample loss.

[0037] In some embodiments, the four-way pipe fitting 1 includes a first cold trap fixed connection base 101, a mechanical pump and molecular pump series connection port 102, a high-power ion pump connection fixed base 103, a conical permanent magnet connection fixed base 104, an ionization system connection fixed base 105, a cold cathode vacuum gauge connection fixed base 106, and a four-way pipe fitting fixed base 107;

[0038] In specific implementation, the four-way pipe fitting 1 is fixedly connected to the frame of the mass spectrometer through the four-way pipe fitting fixed base 107. The first cold trap fixed connection base 101 is used to fix the first cold trap 2 and the molecular beam collimator 3. The high-power ion pump connection fixed base 103 is used to fixedly connect the ion pump. The conical permanent magnet connection fixed base 104 is used to fixedly connect the permanent magnet assembly 5. The ionization system connection fixed base 105 is used to install the ion optical system.

[0039] Among them, the mechanical pump and molecular pump series connection port 102 constitutes a low-vacuum extraction module, which is used to restore the internal vacuum of the instrument when the mass spectrometer is disassembled for maintenance. When the vacuum degree reaches 10⁻ 4 Pa, the vacuum baffle valve of this interface is closed, and the ion pump at the high-power ion pump connection fixed base 103 is started to further improve the vacuum degree. The cold cathode vacuum gauge connection fixed base 106 is used to connect the cold cathode vacuum gauge. This device accurately measures the vacuum degree in the medium and high vacuum range through the discharge phenomenon generated by electrons in a strong electric field and magnetic field. The ion optical system installed on the ionization system connection fixed base 105 can accelerate and focus the ionized sample ions, further improving the quality of the ion beam, thereby enhancing the accuracy and efficiency of mass spectrometry analysis.

[0040] In some embodiments, the first cold trap 2 includes a first liquid nitrogen storage inner tank 202, a first cold trap fixed base 204, and a sample recovery tank 205;

[0041] The first cold trap 2 is fixedly connected to the four-way pipe fitting 1 through the first cold trap fixing seat 204. One side of the first liquid nitrogen storage inner tank 202 is provided with a liquid nitrogen filling port 201, and the other side of the first liquid nitrogen storage inner tank 202 is provided with a sample recovery tank 205. The first liquid nitrogen storage inner tank 202 extends to the sample recovery tank 205. The sample recovery tank 205 is arranged close to the ionization chamber. A first cold trap connection port 203 is also provided outside the first liquid nitrogen storage inner tank 202.

[0042] During specific implementation, in a vacuum container, the gaseous compound exists in a solid-liquid coexistence form at low temperature. When the ambient temperature is lower than -80 °C, the gaseous compound will transform into a solid state through sublimation. To achieve this process, liquid nitrogen is injected through the liquid nitrogen filling port 201 and stored in the first liquid nitrogen storage inner tank 202. This inner tank adopts a Dewar flask design to ensure the long-term stability of the liquid nitrogen temperature. Once filled, the liquid nitrogen can maintain a low-temperature environment for about 24 hours. The first liquid nitrogen storage inner tank 202 extends to the sample recovery tank 205, which is located below the ionization chamber. The un-ionized samples can be effectively trapped through the groove at its end, preventing these samples from adhering to the inner wall of the cavity, and thus avoiding potential hazards to the operators during maintenance. In addition, the effective recovery of the samples also significantly reduces the load on the ion pump and extends its service life. The first cold trap 2 is firmly fixed to the four-way pipe fitting 1 together with the molecular beam collimator 3 through multiple nuts, further ensuring the stable connection and operation safety of the cold trap and the entire system.

[0043] In some embodiments, the second cold trap 4 includes a second liquid nitrogen storage inner tank 402, a second cold trap connection port 403, a second cold trap fixing seat 404, a sample recovery plate 405, and a connection port bellows 406;

[0044] One side of the second liquid nitrogen storage inner tank 402 is provided with a liquid nitrogen injection port 401, the other side of the second liquid nitrogen storage inner tank 402 is provided with a second cold trap fixing seat 404. The second liquid nitrogen storage inner tank 402 extends to the sample recovery plate 405. The sample recovery plate 405 is arranged close to the sample recovery tank 205. A second cold trap connection port 403 adapted to the first cold trap connection port 203 is also provided outside the second liquid nitrogen storage inner tank 402. A connection port bellows 406 is provided on the second cold trap connection port 403.

[0045] During specific implementation, the second cold trap 4 and the first cold trap 2 adopt the same liquid nitrogen injection and storage mechanism. Liquid nitrogen is injected through the liquid nitrogen injection port 401 and stored in the second liquid nitrogen storage inner tank 402. The space of the second liquid nitrogen storage inner tank 402 extends to the end sample recovery plate 405. By increasing the end area, the recovery efficiency of non-ionized samples is significantly improved, ensuring that the samples will not escape within the system, thereby protecting the stability of the vacuum environment and the service life of the equipment. The second cold trap connection port 403 is firmly connected to the first cold trap connection port 203 through a metal clamp, realizing the seamless integration of the two cold trap systems. This not only improves the vacuum extraction efficiency of the system but also ensures the long-term stable operation of the cold trap in a high-vacuum environment. The connection port adopts a bellows structure, further enhancing the convenience of installation and adjustment, improving the flexibility of the second cold trap connection port 403, making the installation of the metal clamp more simple and reliable, and at the same time reducing the risk of seal failure caused by assembly stress.

[0046] In some embodiments, the molecular beam collimator 3 includes a fixed base 301, a molecular beam outlet 302, and a sample injection pipe 303;

[0047] The molecular beam collimator 3 is fixedly connected to the four-way pipe fitting 1 through the fixed base 301. The molecular beam outlet 302 is arranged on one side close to the four-way pipe fitting 1, and the sample injection pipe 303 is arranged outside the fixed base 301.

[0048] During specific implementation, the sample to be analyzed is injected into the molecular beam collimator 3 through the sample injection pipe 303 under the control of the electromagnetic pneumatic combined valve at the inlet system end. The molecular beam collimator 3 is made by pressing multiple layers of gold foil. Utilizing the precise separation and collimation ability of the gold foil, the gas molecules are homogenized to generate a highly stable, pure, and molecular beam with a clear directionality. It can effectively reduce the scattering effect in the molecular beam, ensure that the molecules maintain a consistent path and momentum distribution when passing through the ionization region, thereby significantly improving the efficiency of the ion source and the accuracy of the ionization process. In addition, the molecular beam collimator 3 made of gold foil pressing can also reduce the background noise and the collision probability between molecules, reduce the energy loss, improve the focusing effect and transmission efficiency of the molecular beam. This significantly enhances the resolution and data reliability of mass spectrometry analysis and provides more ideal initial conditions for the mass analysis and detection links, thereby improving the analysis performance of the overall system.

[0049] In some embodiments, the permanent magnet assembly 5 includes a conical permanent magnet 501 and a magnet fixing seat 502;

[0050] The conical permanent magnet 501 is fixedly connected to the four-way pipe fitting 1 through the magnet fixing seat 502. A magnet with a magnetic pole opposite to the conical section of the conical permanent magnet 501 is arranged inside the four-way pipe fitting 1 to form magnetic lines of force between the ionization chambers.

[0051] In specific implementation, the lower end of the conical permanent magnet 501 is designed to be conical, and a fixed magnet of opposite polarity is provided inside the four-way pipe 1 below it. This configuration forms uniform and highly concentrated magnetic lines of force between the ionization chambers, significantly enhancing the magnetic field environment inside the ionization chamber. The application of the conical permanent magnet 501 effectively extends the movement path of the electrons generated by the tungsten filament in the ionization chamber, increases the collision probability between the electrons and the sample molecules drawn by the molecular beam, and thus greatly improves the efficiency of electron ionization. The magnetic field configuration can also slow down the attenuation of electron energy, ensuring that the electrons maintain sufficient energy in the ionization chamber to effectively collide with the sample molecules, further improving the ionization efficiency and the stability of ion generation, and reducing sample loss.

[0052] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0053] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus / device.

[0055] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. An electron ionization type mass spectrometer front-stage system, characterized in that, It includes a four-way pipe fitting (1), a first cold trap (2), a molecular beam collimator (3), a second cold trap (4), and a permanent magnet assembly (5): A plurality of fixed seats are provided on the four-way pipe fitting (1). The four-way pipe fitting (1) is fixedly connected to the frame of the mass spectrometer. The first cold trap (2) and the molecular beam collimator (3) are fixedly arranged on one side of the four-way pipe fitting (1). The second cold trap (4) is arranged on the other side of the four-way pipe fitting (1). The first cold trap (2) is connected to the second cold trap (4). The permanent magnet assembly (5) is fixedly connected to the four-way pipe fitting (1); Wherein, the first cold trap (2) and the second cold trap (4) can trap the un-ionized samples.

2. The pre-stage system of an electron ionization type mass spectrometer according to claim 1, characterized in that The four-way pipe fitting (1) includes a four-way pipe fitting fixed base (107); The four-way pipe fitting (1) is fixedly connected to the frame of the mass spectrometer through the four-way pipe fitting fixed base (107).

3. The pre-stage system of an electron ionization type mass spectrometer according to claim 1, characterized in that, The first cold trap (2) includes a first liquid nitrogen storage inner tank (202), a first cold trap fixed seat (204), and a sample recovery tank (205); The first cold trap (2) is fixedly connected to the four-way pipe fitting (1) through the first cold trap fixed seat (204). A liquid nitrogen filling port (201) is arranged on one side of the first liquid nitrogen storage inner tank (202). The sample recovery tank (205) is arranged on the other side of the first liquid nitrogen storage inner tank (202). The first liquid nitrogen storage inner tank (202) extends to the sample recovery tank (205). The sample recovery tank (205) is arranged close to the ionization chamber. A first cold trap connection port (203) is also arranged outside the first liquid nitrogen storage inner tank (202).

4. The pre-stage system of an electron ionization type mass spectrometer according to claim 3, characterized in that, The second cold trap (4) includes a second liquid nitrogen storage inner tank (402), a second cold trap connection port (403), a second cold trap fixed seat (404), a sample recovery plate (405), and a connection port bellows (406); A liquid nitrogen injection port (401) is arranged on one side of the second liquid nitrogen storage inner tank (402). The second cold trap fixed seat (404) is arranged on the other side of the second liquid nitrogen storage inner tank (402). The second liquid nitrogen storage inner tank (402) extends to the sample recovery plate (405). The sample recovery plate (405) is arranged close to the sample recovery tank (205). A second cold trap connection port (403) adapted to the first cold trap connection port (203) is also arranged outside the second liquid nitrogen storage inner tank (402). A connection port bellows (406) is arranged on the second cold trap connection port (403).

5. An ionization type mass spectrometer front stage system according to claim 1, characterized in that The molecular beam collimator (3) includes a fixed base (301), a molecular beam outlet (302), and a sample injection pipe (303); The molecular beam collimator (3) is fixedly connected to the four-way pipe fitting (1) through the fixed base (301). The molecular beam outlet (302) is arranged on the side close to the four-way pipe fitting (1). The sample injection pipe (303) is arranged outside the fixed base (301).

6. The pre-stage system of an electron ionization type mass spectrometer according to claim 1, characterized in that, The permanent magnet assembly (5) includes a conical permanent magnet (501) and a magnet fixed seat (502); The conical permanent magnet (501) is fixedly connected to the four-way pipe fitting (1) through the magnet fixing seat (502).

7. The pre-stage system of an electron ionization type mass spectrometer according to claim 6, characterized in that, A magnet with a magnetic pole opposite to that of the conical section of the conical permanent magnet (501) is arranged inside the four-way pipe fitting (1), and magnetic lines of force are formed between the ionization chambers.

8. An ion source system for an electron ionization mass spectrometer according to claim 5, wherein, The molecular beam collimator (3) is formed by pressing multiple layers of gold foil.

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