Electronic ionization type mass spectrometer preceding-stage system

Abstract

The invention belongs to the field of mass spectrometry, particularly relates to an electron ionization type mass spectrometer preceding-stage system, and aims to solve the problems of low ionization efficiency and sample dissipation of a traditional mass spectrometer in gas compound analysis in the prior art. The device comprises a four-way pipe fitting, a first cold trap, a molecular beam collimator, a second cold trap and a permanent magnet assembly, the four-way pipe fitting is provided with a plurality of fixing seats, the four-way pipe fitting is fixedly connected with a rack of a 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, and the permanent magnet assembly is arranged on the other side of the four-way pipe fitting. The first cold trap is connected with the second cold trap, and the permanent magnet assembly is fixedly connected with the four-way pipe fitting, so that the recovery efficiency of an unionized sample is remarkably improved, and the problems of low ionization efficiency, sample dissipation, vacuum degree reduction, equipment corrosion and the like of a traditional mass spectrometer in gas compound analysis are solved.

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 gas 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 gas compounds. The products formed by the reaction of some highly volatile gas 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 gas compounds increase the complexity of equipment maintenance operations and safety risks for staff, and also pose a potential threat to the environment. Summary of the Invention

[0004] To solve the problems of low ionization efficiency and sample escape faced by traditional mass spectrometers in the analysis of gas 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: 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; Wherein, the first cold trap and the second cold trap can capture un-ionized samples.

[0005] 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; The four-way pipe fitting is fixedly connected to the frame of the mass spectrometer through the four-way pipe fitting fixed base.

[0006] 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 container, a first cold trap fixed seat, and a sample recovery tank; 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 tank is provided with a liquid nitrogen filling port, and the other side of the first liquid nitrogen storage inner tank is provided with the sample recovery tank. The first liquid nitrogen storage inner tank extends to the sample recovery tank, the sample recovery tank is arranged close to the ionization chamber, and a first cold trap connection port is further arranged outside the first liquid nitrogen storage inner tank.

[0007] 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 tank, a second cold trap connection port, a second cold trap fixing seat, a sample recovery plate, and a connection port bellows; One side of the second liquid nitrogen storage inner tank is provided with a liquid nitrogen injection port, the other side of the second liquid nitrogen storage inner tank is provided with the second cold trap fixing seat, the second liquid nitrogen storage inner tank extends to the sample recovery plate, the sample recovery plate is arranged close to the sample recovery tank, a second cold trap connection port adapted to the first cold trap connection port is further arranged outside the second liquid nitrogen storage inner tank, and a connection port bellows is arranged on the second cold trap connection port.

[0008] 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; 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.

[0009] 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; The conical permanent magnet is fixedly connected to the four-way pipe fitting through the magnet fixing seat.

[0010] 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 field line between the ionization chambers.

[0011] 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.

[0012] Advantages of the present invention: The first cold trap and the second cold trap adopt a double-spherical cold trap design, which significantly improves the recovery efficiency of un-ionized samples. Cooperating with an efficient vacuum management system, it realizes faster vacuum extraction and sensitive vacuum degree feedback, ensuring the stable operation of the system.

[0013] The molecular beam collimator can ensure that gas compound molecules enter the ionization chamber evenly, improving 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 enhancing the reliability of the equipment.

[0014] 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 technology analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other features, objects, and advantages of the present application will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 It is a structural diagram of the front-stage system of an ionization type mass spectrometer according to some embodiments of the present application; Figure 2 It is a structural diagram of a four-way pipe fitting according to some embodiments of the present application; Figure 3 It is a structural diagram of a first cold trap according to some embodiments of the present application; Figure 4 It is a structural diagram of a molecular beam collimator according to some embodiments of the present application; Figure 5 It is a structural diagram of a second cold trap according to some embodiments of the present application; Figure 6 It is a structural diagram of a conical permanent magnet according to some embodiments of the present application.

[0016] In the figures: 1. Four-way pipe fitting; 101. Fixed connection base for the first cold trap; 102. Series connection port for mechanical pump and molecular pump; 103. Fixed connection base for high-power ion pump; 104. Fixed connection base for conical permanent magnet; 105. Fixed connection base for ionization system; 106. Fixed connection base for cold cathode vacuum gauge; 107. Fixed base for four-way pipe fitting; 2. First cold trap; 201. Liquid nitrogen filling port; 202. First liquid nitrogen storage inner tank; 203. Connection port for the first cold trap; 204. Fixed seat for 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 for the second cold trap; 404. Fixed seat for the second cold trap; 405. Sample recovery plate; 406. Connection port bellows; 5. Permanent magnet assembly; 501. Conical permanent magnet; 502. Magnet fixed seat. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention and are not intended to limit the invention. Additionally, it should be noted that for the sake of description, only the parts related to the relevant invention are shown in the drawings.

[0018] 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.

[0019] As Figures 1-6 shown, the present invention provides a pre-stage system for 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: A plurality of fixing 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, and the permanent magnet assembly 5 is fixedly connected to the four-way pipe fitting 1; Among them, the first cold trap 2 and the second cold trap 4 can trap the un-ionized samples.

[0020] 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 trap the un-ionized samples, which can protect the stability of the vacuum environment and extend the service 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 chamber, improving the ionization efficiency and the stability of ion generation, and reducing the sample loss.

[0021] In some embodiments, the four-way pipe fitting 1 includes a first cold trap fixed connection fixing seat 101, a mechanical pump and molecular pump series connection port 102, a high-power ion pump connection fixing seat 103, a conical permanent magnet connection fixing seat 104, an ionization system connection fixing seat 105, a cold cathode vacuum gauge connection fixing seat 106, and a four-way pipe fitting fixed base 107; 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 fixing seat 101 is used to fix the first cold trap 2 and the molecular beam collimator 3. The high-power ion pump connection fixing seat 103 is used to fixedly connect the ion pump. The conical permanent magnet connection fixing seat 104 is used to fixedly connect the permanent magnet assembly 5. The ionization system connection fixing seat 105 is used to install the ion optical system.

[0022] Among them, the series connection port 102 of the mechanical pump and the molecular pump constitutes a low-vacuum extraction module, which is used to restore the internal vacuum of the instrument during disassembly and maintenance of the mass spectrometer. When the vacuum degree reaches 10⁻ 4 Pa, the vacuum baffle valve at this interface is closed, and the ion pump at the ion pump connection fixing seat 103 with high power is started to further increase the vacuum degree. The cold cathode vacuum gauge connection fixing seat 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 ionization system connection fixing seat 105 is equipped with an ion optical system that 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.

[0023] In some embodiments, the first cold trap 2 includes a first liquid nitrogen storage inner tank 202, a first cold trap fixing 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 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.

[0024] During specific implementation, in a vacuum container, gas compounds exist in a solid-liquid coexistence form at low temperatures. When the ambient temperature is lower than -80 °C, the gas compounds 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 the maintenance process. 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 a plurality of nuts, further ensuring the stable connection and operation safety of the cold trap and the entire system.

[0025] 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; On one side of the second liquid nitrogen storage inner liner 402, there is a liquid nitrogen injection port 401. On the other side of the second liquid nitrogen storage inner liner 402, there is a second cold trap fixing seat 404. The second liquid nitrogen storage inner liner 402 extends to the sample recovery plate 405. The sample recovery plate 405 is arranged close to the sample recovery groove 205. Outside the second liquid nitrogen storage inner liner 402, there is also a second cold trap connection port 403 adapted to the first cold trap connection port 203. A connection port bellows 406 is arranged on the second cold trap connection port 403.

[0026] 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 liner 402. The space of the second liquid nitrogen storage inner liner 402 extends to the end sample recovery plate 405. By increasing the end area, the recovery efficiency of the non-ionized sample is significantly improved, ensuring that the sample will not escape in 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.

[0027] In some embodiments, 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 one side close to the four-way pipe fitting 1. The sample injection pipe 303 is arranged outside the fixed base 301.

[0028] 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. Using 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 direction. 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 the 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.

[0029] In some embodiments, the permanent magnet assembly 5 includes a conical permanent magnet 501 and a magnet fixing base 502; The conical permanent magnet 501 is fixedly connected to the four-way pipe fitting 1 through the magnet fixing base 502. 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.

[0030] Specifically, when implemented, the lower end of the conical permanent magnet 501 is designed to be conical, and a fixed magnet with an opposite polarity is arranged inside the four-way pipe fitting 1 below it. This configuration forms magnetic lines of force with uniform intensity and high concentration between the ionization chambers, significantly enhancing the magnetic field environment inside the ionization chambers. The application of the conical permanent magnet 501 effectively extends the movement path of the electrons generated by the tungsten wire inside the ionization chamber, increases the collision probability between the electrons and the sample molecules introduced by the molecular beam, and thus greatly improves the efficiency of electron ionization. The magnetic field configuration can also slow down the attenuation of the electron energy, ensure that the electrons maintain sufficient energy inside the ionization chamber to effectively collide with the sample molecules, further improve the ionization efficiency and the stability of ion generation, and reduce the sample loss.

[0031] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description and does 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 a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0032] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0033] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, so that a process, method, article, or device / equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent in these processes, methods, articles, or devices / equipment.

[0034] So far, the technical solution of the present invention has 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 mass spectrometer pre-stage system, characterized in that: It comprises a four-way pipe (1), a first cold trap (2), a molecular beam collimator (3), a second cold trap (4) and a permanent magnet assembly (5): The four-way pipe fitting (1) is provided with a plurality of fixing seats, the four-way pipe fitting (1) is fixedly connected to a frame of a 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); The first cold trap (2) and the second cold trap (4) are capable of capturing unionized samples.

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

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

4. The electron ionization mass spectrometer pre-stage system according to claim 3, characterized in that: The second cold trap (4) comprises a second liquid nitrogen storage liner (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); A liquid nitrogen injection port (401) is provided on one side of the second liquid nitrogen storage liner (402), and a second cold trap fixing seat (404) is provided on the other side of the second liquid nitrogen storage liner (402). The second liquid nitrogen storage liner (402) extends to the sample recovery plate (405), and 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 on the outside of the second liquid nitrogen storage liner (402), and a connection port bellows (406) is provided on the second cold trap connection port (403).

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

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

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

8. The electron ionization mass spectrometer pre-stage system according to claim 5, characterized in that: The molecular beam collimator (3) is formed by pressing multiple layers of gold foil.

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