A dual ionization source for aerosol mass spectrometer

Abstract

This utility model relates to the field of mass spectrometry technology, and particularly to a dual ionization source specifically for aerosol mass spectrometry. It includes a stabilizing and voltage-stabilizing chamber, a sample introduction capillary, an ionization chamber, and a vacuum system. The stabilizing and voltage-stabilizing chamber is connected to the ionization chamber via the sample introduction capillary. The outlet end is sequentially connected to a lens group, a quadrupole assembly, an electron multiplier, and a Faraday cup. The vacuum gauge monitors the vacuum level in real time. This dual ionization source for aerosol mass spectrometry, through the arrangement of components such as a vacuum ultraviolet lamp ionization source, an electron impact ionization source, a heating element, and a temperature sensor, and the synergistic relationship between the vacuum ultraviolet lamp ionization source and the electron impact ionization source, allows for the selective or simultaneous use of the dual ionization sources to ionize different types of samples. This achieves the effect of highly efficient ionization of various organic compounds selected through the synergistic effect of the two ionization sources.

Description

Technical Field

[0001] This utility model relates to the field of mass spectrometry technology, and in particular to a dual ionization source specifically for aerosol mass spectrometers. Background Technology

[0002] As a key component of mass spectrometry instruments, the ion source functions to ionize sample molecules under a high vacuum environment. Ionized molecules, having absorbed excessive energy, further fragment into various smaller fragment ions and neutral particles. Subsequently, under the influence of an accelerating electric field, these ions and particles acquire the same average kinetic energy and enter the mass analyzer. Currently, most traditional mass spectrometers on the market use a single ionization source, such as electron impact ionization, chemical ionization, or electrospray ionization. While these traditional ionization methods have been used for many years, each has significant drawbacks. For example, electron impact ionization, when dealing with samples with low volatility and poor thermal stability, struggles to effectively achieve sample ionization. The vaporization and ionization of samples greatly limit the range of detectable samples. Taking thermally unstable biomolecules as an example, these samples are easily decomposed during electron bombardment, making it impossible to obtain complete and accurate mass spectrometry information. Furthermore, chemical ionization sources are cumbersome and complex to operate in practice, requiring operators to precisely control the partial pressure and temperature of the reaction gas. If there is a slight deviation in the partial pressure of the reaction gas or the temperature control is not precise enough, the reaction may not proceed as expected, thus affecting the ionization effect of the sample and greatly increasing the difficulty of mass spectrum interpretation. In severe cases, it may even lead to erroneous analytical results. Therefore, it is necessary to design a dual ionization source specifically for aerosol mass spectrometers to solve the above problems. Utility Model Content

[0003] The main objective of this invention is to provide a dual ionization source specifically for aerosol mass spectrometers, which can effectively solve the problems in the background art.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0005] A dual ionization source for aerosol mass spectrometer includes a pulse and voltage stabilization chamber, a sample inlet capillary, an ionization chamber, and a vacuum system. The pulse and voltage stabilization chamber is connected to the ionization chamber through the sample inlet capillary, and the inlet end of the sample inlet capillary is connected to the sample gas inlet.

[0006] The ionization chamber integrates two ionization sources: a vacuum ultraviolet lamp ionization source and an electron bombardment ionization source. The electron bombardment ionization source includes a repulsion electrode and a tungsten filament. The outer wall of the ionization chamber is equipped with a heating element, a temperature sensor, and a magnet. A very narrow slit on the right side connects to the electron transmission chamber. The outlet end is sequentially connected to a lens group, a quadrupole assembly, an electron multiplier, and a Faraday cup. The vacuum system consists of a molecular pump, a backing pump, and a vacuum gauge. The molecular pump is connected to the ionization chamber and evacuates the system via the backing pump. The vacuum gauge monitors the system vacuum level in real time.

[0007] Preferably, the pressure stabilizing chamber and the sample inlet capillary are connected by a flange seal, and the pressure in the pressure stabilizing chamber is dynamically balanced by adjusting the flow rate of the sample gas.

[0008] Preferably, the vacuum ultraviolet lamp ionization source consists of a VUV lamp and an ionizer, wherein the VUV lamp includes a discharge quartz lamp tube, a radio frequency coil, a Kr / He mixed gas distribution system, and a magnesium fluoride window.

[0009] Preferably, the tungsten filaments of the electron bombardment ionization source are symmetrically arranged on both sides of the repulsion pole, the magnet covers the outer wall of the ionization chamber to form an axial magnetic field, and the inner wall of the ionization chamber is embedded with a temperature sensor and a heating element is used to achieve constant temperature control.

[0010] Preferably, the heating element has a heating temperature range of room temperature to 300°C, and the temperature sensor has a monitoring accuracy of ±0.5°C to ensure stable temperature in the ionization chamber.

[0011] Preferably, the lens group and the ion transport electrode form a focusing electric field, which focuses the ion beam generated by ionization and transmits it to the quadrupole assembly. The ions after mass analysis are detected by an electron multiplier or a Faraday cup.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. In this utility model, by integrating a vacuum ultraviolet lamp ionization source and an electron impact ionization source, the vacuum ultraviolet lamp ionization source can be used independently when processing such samples. The vacuum ultraviolet light it generates is a soft ionization method, which can ionize sample molecules under mild conditions, minimizing sample decomposition. This solves the problem of poor ionization effect of traditional electron impact ionization sources on volatile and thermally unstable samples, ensuring the acquisition of clear molecular ion peaks and improving the detection capability for such samples.

[0014] 2. In this utility model, by setting up a stabilizing and pressure-stabilizing chamber, a heating element, a temperature sensor, a vacuum system, a pre-pump, and a vacuum gauge, the stabilizing and pressure-stabilizing chamber achieves dynamic pressure balance by adjusting the flow rate of the sample gas inlet. The heating element and the temperature sensor work together to maintain a constant temperature in the ionization chamber. The vacuum system precisely controls the vacuum level, without relying on the reaction gas. Furthermore, the dual ionization sources allow for flexible selection of ionization methods and adjustment of power, simplifying the operation process and avoiding the problem of ionization effect being affected by improper control of reaction gas parameters, thus improving the ease of operation and ionization stability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of a dual ionization source for an aerosol mass spectrometer according to the present invention.

[0016] In the diagram: 1. Stabilizing chamber; 2. Sample gas inlet; 3. Inlet capillary; 4. Repulsor; 5. Ionization chamber; 6. Heating element; 7. Magnet; 8. Lens assembly; 9. Quadrupole assembly; 10. Tungsten filament; 11. Molecular pump; 12. Backing pump; 13. Vacuum gauge; 14. Electron multiplier; 15. Faraday cup; 16. Temperature sensor; 17. Two ionization sources. Detailed Implementation

[0017] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0018] In the description of this utility model, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," and "connected," etc., should be interpreted broadly. For example, "connected" 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 an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0020] Please see Figure 1This utility model provides a technical solution:

[0021] A dual ionization source for aerosol mass spectrometry includes a stabilizing and voltage-stabilizing chamber 1, a sample inlet capillary 3, an ionization chamber 5, and a vacuum system. The coordinated operation of these core structures provides the basic framework for the stable operation of the dual ionization source, ensuring the orderly execution of the entire process from sample gas inlet to ion detection. The stabilizing and voltage-stabilizing chamber 1 is connected to the ionization chamber 5 via the sample inlet capillary 3. This connection allows the sample gas to be stably transmitted along a preset path, avoiding disturbances during transmission and ensuring the stability of the sample gas entering the ionization chamber 5. The inlet end of the sample inlet capillary 3 is connected to the sample gas inlet 2, enabling the sample gas to accurately enter the system and providing a sufficient and continuous sample source for subsequent ionization analysis. The ionization chamber 5 integrates two ionization sources 17, and this integrated design significantly reduces energy consumption. This design saves space and allows two ionization sources to act more efficiently on samples in the same area, improving synergistic ionization effects. The two ionization sources 17 are a vacuum ultraviolet lamp ionization source and an electron impact ionization source, respectively. Each ionization source has its own advantages and can meet the ionization needs of different types of samples, broadening the instrument's applicability. The electron impact ionization source includes a repulsion electrode 4 and a tungsten filament 10. The repulsion electrode 4 effectively guides the direction of electron movement, while the tungsten filament 10 provides a stable source for electron generation, together ensuring efficient electron impact ionization. The outer wall of the ionization chamber 5 is equipped with a heating element 6, a temperature sensor 16, and a magnet 7. The heating element 6 can adjust the temperature inside the ionization chamber 5, the temperature sensor 16 monitors the temperature in real time, and the magnet 7 optimizes the electron trajectory. The three work together... To create a suitable environment for ionization, an extremely narrow slit is provided on the right side to connect to the electron transport chamber. This slit filters out ions that meet the requirements to enter the transport chamber, reducing interference from irrelevant ions and improving the accuracy of subsequent detection. The outlet end is sequentially connected to lens group 8, quadrupole assembly 9, electron multiplier 14, and Faraday cup 15. This connection sequence forms a complete ion transport and detection chain, ensuring that ions can be accurately analyzed and detected. The vacuum system consists of molecular pump 11, backing pump 12, and vacuum gauge 13. Molecular pump 11 provides a high vacuum environment, backing pump 12 assists in evacuation, and vacuum gauge 13 monitors the vacuum level, all working together to maintain the required vacuum conditions of the system. Molecular pump 11 is connected to ionization chamber 5 and evacuates through backing pump 12, ensuring that ionization chamber 5 is in a vacuum. The system operates under high vacuum, meeting the requirements of dual ionization sources. Vacuum gauge 13 monitors the system vacuum level in real time, providing timely feedback for easy operator adjustments and ensuring system vacuum stability. The stabilizing chamber 1 and the sample inlet capillary 3 are connected by a flange seal, ensuring strong sealing and preventing sample gas leakage, thus guaranteeing stable system pressure. Furthermore, the pressure within the stabilizing chamber 1 is dynamically balanced by adjusting the flow rate of the sample gas inlet 2. This dynamic pressure balance allows the sample gas to enter the ionization chamber 5 at a stable flow rate, ensuring consistency in the ionization process. The vacuum ultraviolet lamp ionization source consists of a VUV lamp and an ionizer. The VUV lamp provides vacuum ultraviolet light, while the ionizer provides the environment for the ionization reaction; together, they achieve vacuum ultraviolet lamp ionization.The VUV lamp comprises a discharge quartz lamp tube, an RF coil, a Kr / He mixed gas distribution system, and a magnesium fluoride window. The RF power supply operates at a frequency of 13.56 MHz and has a normal operating power of 60 W. The RF power supply excites an inert gas (5% Kr gas, with He gas as a buffer gas) through the coil to generate vacuum ultraviolet light. The pressure of the Kr gas inside the quartz lamp tube is 250 Pa. The vacuum ultraviolet light passes through the magnesium fluoride window and enters the ionizer, achieving a photon flux of 6.6 × 10¹⁴ s⁻¹·cm⁻² and photon energies of 10.0 eV (80%) and 10.6 eV (20%). The sample analyte enters the ionizer through the sample introduction system. At this point, the ion source operates at a pressure of 1300 Pa. After being irradiated by VUV light, single-photon ionization occurs, and the generated ions subsequently enter the ion transport system. These components work together... The system provides stable conditions for the generation of vacuum ultraviolet light, ensuring a stable supply of energy required for ionization. The tungsten filament 10 of the electron bombardment ionization source is symmetrically arranged on both sides of the repulsion electrode 4. This symmetrical arrangement makes electron emission more uniform, increases the probability of collisions between electrons and sample molecules, and enhances the ionization effect. The magnet 7 covers the outer wall of the ionization chamber 5 to form an axial magnetic field. The axial magnetic field can constrain the trajectory of electrons, prolong the residence time of electrons in the ionization chamber 5, and improve the ionization efficiency. The inner wall of the ionization chamber 5 is embedded with a temperature sensor 16 and is connected to the repulsion electrode 4. The superheater 6 achieves constant temperature control, and the temperature sensor 16 accurately senses temperature changes. The superheater 6 adjusts its heating power in a timely manner to ensure a constant temperature within the ionization chamber 5. The heating temperature range of the superheater 6 is from room temperature to 300℃, a wide range that meets the ionization temperature requirements of different samples, improving the instrument's adaptability. The temperature sensor 16 has a monitoring accuracy of ±0.5℃, ensuring temperature stability within the ionization chamber 5. High-precision temperature monitoring can promptly detect minute temperature changes and provide feedback for adjustment, ensuring a stable ionization environment. The lens group 8 and the ion transmission electrode form a focusing electric field, focusing the ion beam generated by ionization and transmitting it to the quadrupole assembly 9. The focusing electric field makes the ion beam more concentrated, reducing ion loss during transmission and increasing the number of ions reaching the quadrupole assembly 9. After quality analysis, the ions are detected by the electron multiplier 14 or the Faraday cup 15. The electron multiplier 14 can detect weak ion signals, while the Faraday cup 15 is suitable for strong signal detection. The two work together to meet the detection needs of ions of different intensities.

[0022] Example 1: When detecting volatile organic small molecule samples, the sample gas enters the stabilizing chamber 1 from the sample gas inlet 2. The pressure inside the stabilizing chamber 1 is dynamically balanced by adjusting the flow rate. The gas then enters the ionization chamber 5 through the sample capillary 3. At this time, the vacuum ultraviolet lamp ionization source is turned on. The discharge quartz tube of the VUV lamp excites the Kr / He mixed gas under the action of the radio frequency coil to generate vacuum ultraviolet light, which enters the ionizer through the magnesium fluoride window. Simultaneously, the heating element 6 controls the temperature of the ionization chamber 5 at 50°C. The temperature sensor 16... Real-time monitoring ensures the temperature remains stable within ±0.5℃. The axial magnetic field formed by magnet 7 confines the movement of electrons. In the vacuum system, molecular pump 11 and backing pump 12 evacuate the ionization chamber 5 to a vacuum level of 10⁻³ Pa. Vacuum gauge 13 monitors in real time. Sample molecules are ionized under vacuum ultraviolet light. The generated ions are assisted by repulsion electrode 4 and enter the electron transfer chamber through an extremely narrow slit. After being focused by lens group 8, they are transferred to quadrupole assembly 9 for mass analysis. Finally, the electron multiplier 14 detects a clear molecular ion peak.

[0023] Example 2: When analyzing high-boiling-point organic macromolecular samples, the sample gas enters the ionization chamber 5 through the sample gas inlet 2, the stabilizing and pressure-stabilizing chamber 1, and the sample capillary 3. The heating element 6 heats the ionization chamber 5 to 250°C, and the temperature sensor 16 ensures temperature stability. At the same time, the electron bombardment ionization source is turned on, and the tungsten filament 10 emits electrons, which are accelerated to bombard the sample molecules under the action of the repulsion electrode 4. The vacuum system maintains a vacuum of 10⁻⁴ Pa in the ionization chamber 5, and the magnet 7 enhances the collision probability between electrons and sample molecules. The ions generated by ionization are focused by the lens group 8 and enter the quadrupole assembly 9. The ions after mass analysis are detected by the Faraday cup 15. Combined with the auxiliary ionization of the vacuum ultraviolet lamp ionization source, the ionization efficiency and detection sensitivity of macromolecular samples are significantly improved.

[0024] It should be noted that this utility model is a dual ionization source specifically for an aerosol mass spectrometer. The sample gas enters the stabilizing chamber 1 from the sample gas inlet 2. The stabilizing chamber 1 achieves dynamic pressure balance by adjusting the flow rate of the sample gas inlet 2. Subsequently, the sample gas is transported to the ionization chamber 5 via the sample inlet capillary 3 and the stabilizing chamber 1 through a flange seal. In the vacuum system, the molecular pump 11 evacuates the ionization chamber 5 through the back pump 12. The vacuum gauge 13 monitors the system vacuum level in real time to maintain a pressure environment of 10⁻⁵ Pa to 1000 Pa inside the ionization chamber 5. The heating element 6 on the outer wall of the ionization chamber 5 controls the temperature between room temperature and 300°C, and the temperature sensor 16 on the inner wall monitors the temperature with an accuracy of ±0.5°C to ensure constant temperature. At the same time, the magnet 7 covers... An axial magnetic field is formed on the outer wall of the ionization chamber 5. At this time, the two ionization sources 17 integrated in the ionization chamber 5 start to work. The VUV lamp of the vacuum ultraviolet lamp ionization source generates vacuum ultraviolet light to ionize the sample gas through the discharge quartz lamp tube, radio frequency coil, Kr / He mixed gas distribution system and magnesium fluoride window. The tungsten filament 10 of the electron bombardment ionization source is symmetrically arranged on both sides of the repulsion electrode 4. The electrons emitted by the tungsten filament 10 ionize the sample gas under the action of the repulsion electrode 4. The ion generated by ionization enters the electron transmission chamber through the extremely narrow slit on the right side of the ionization chamber 5. After being focused by the focusing electric field formed by the lens group 8 and the ion transmission electrode, it is transmitted to the quadrupole assembly 9. The ions after mass analysis by the quadrupole assembly 9 are finally detected by the electron multiplier 14 or the Faraday cup 15.

[0025] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A dual ionization source for an aerosol mass spectrometer, comprising a voltage and charge stabilization chamber (1), a sample inlet capillary (3), an ionization chamber (5), and a vacuum system, characterized in that: The stabilizing and stabilizing chamber (1) is connected to the ionization chamber (5) through the sample inlet capillary (3), and the inlet end of the sample inlet capillary (3) is connected to the sample gas inlet (2). The ionization chamber (5) integrates two ionization sources (17), which are a vacuum ultraviolet lamp ionization source and an electron bombardment ionization source, respectively. The electron bombardment ionization source includes a repulsion electrode (4) and a tungsten filament (10). The outer wall of the ionization chamber (5) is provided with a heating plate (6), a temperature sensor (16) and a magnet (7). A very narrow slit is provided on the right side to connect to the electron transmission chamber. The outlet end is connected in sequence to a lens group (8), a quadrupole assembly (9), an electron multiplier (14) and a Faraday cup (15). The vacuum system consists of a molecular pump (11), a back pump (12) and a vacuum gauge (13). The molecular pump (11) is connected to the ionization chamber (5) and evacuates through the back pump (12). The vacuum gauge (13) monitors the vacuum level of the system in real time.

2. The dual ionization source according to claim 1, characterized in that: The pressure stabilizing chamber (1) and the sample inlet capillary (3) are connected by a flange seal, and the pressure inside the pressure stabilizing chamber (1) is dynamically balanced by adjusting the flow rate of the sample gas inlet (2).

3. The dual ionization source according to claim 1, characterized in that: The vacuum ultraviolet lamp ionization source consists of a VUV lamp and an ionizer, wherein the VUV lamp includes a discharge quartz lamp tube, a radio frequency coil, a Kr / He mixed gas distribution system, and a magnesium fluoride window.

4. The dual ionization source according to claim 1, characterized in that: The tungsten filament (10) of the electron bombardment ionization source is symmetrically arranged on both sides of the repulsion electrode (4). The magnet (7) covers the outer wall of the ionization chamber (5) to form an axial magnetic field. The inner wall of the ionization chamber (5) is embedded with a temperature sensor (16) and constant temperature control is achieved through a heating element (6).

5. The dual ionization source according to claim 1, characterized in that: The heating element (6) has a heating temperature range of room temperature to 300°C, and the temperature sensor (16) has a monitoring accuracy of ±0.5°C, ensuring that the temperature inside the ionization chamber (5) is stable.

6. The dual ionization source for aerosol mass spectrometer according to claim 1, characterized in that: The lens group (8) forms a focusing electric field with the ion transport electrode, which focuses the ion beam generated by ionization and transmits it to the quadrupole assembly (9). The ions after mass analysis are detected by the electron multiplier (14) or the Faraday cup (15).

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