WO2021120539A1 - 一种电子轰击电离源装置、电离轰击方法及物质分析方法 - Google Patents

一种电子轰击电离源装置、电离轰击方法及物质分析方法 Download PDF

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WO2021120539A1
WO2021120539A1 PCT/CN2020/094906 CN2020094906W WO2021120539A1 WO 2021120539 A1 WO2021120539 A1 WO 2021120539A1 CN 2020094906 W CN2020094906 W CN 2020094906W WO 2021120539 A1 WO2021120539 A1 WO 2021120539A1
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electron
ionization
electrons
filament
ionization chamber
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PCT/CN2020/094906
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English (en)
French (fr)
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黄泽建
江游
方向
戴新华
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中国计量科学研究院
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Priority to PCT/CN2020/094906 priority Critical patent/WO2021120539A1/zh
Publication of WO2021120539A1 publication Critical patent/WO2021120539A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • G01N27/64—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/10—Ion sources; Ion guns
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/10—Ion sources; Ion guns
    • H01J49/14—Ion sources; Ion guns using particle bombardment, e.g. ionisation chambers

Definitions

  • This application belongs to the field of electronic technology, and in particular relates to an electron bombardment ionization source device, an ionization bombardment method, and a substance analysis method.
  • Electron impact ionization source is a traditional ion source method for mass spectrometers. It uses thermionic emission and is accelerated by a certain intensity of electric field to make it have a certain energy, and then collides with the molecules of the analyte. Through energy exchange, the molecules ionize into product ions. More energy, and will be further fragmented into fragment ions. These molecular ions and fragment ions are used as molecular fingerprints, which can be used as the basis for judging molecular structure, and have become a standard method. The fingerprints of these molecules have been established as a standard EI source standard mass spectrum database, which is widely used, such as the NIST library and the Willey mass spectrum database.
  • the electron bombardment ionization source is the most widely used ion source for mass spectrometers.
  • the most commonly used structure is a cross-beam structure, as shown in Figure 1. It is usually composed of an ionization chamber, a filament, an electron repeller, an electron receiver, and an ion pusher. Repellent, ion focusing lens group, and magnets, etc.
  • the filament is usually made of a cathode material with a high emission current density. After enough current is passed through the lamp, the lamp generates heat and then releases thermionic electrons.
  • the electrons Under the action of the electric field formed between the electron repeller and the ionization chamber, the electrons obtain the corresponding energy, and then fly into the ionization chamber through the corresponding electron hole on the ionization chamber.
  • the interior of the ionization chamber is usually a uniform electric field. Therefore, the electrons remain Continue to fly at a constant speed, then pass through the corresponding electron hole in the ionization chamber, and then be received by the electron receiving electrode.
  • the flow of gas molecules enters the ionization chamber in a direction perpendicular to the direction of electron movement, and collides in the center of the ionization chamber. The electron transfers energy to the molecule through collision.
  • the molecule When the energy of the electron exceeds the ionization energy of the molecule, the molecule loses an electron, which becomes positively charged and becomes a molecular ion. Excessive energy will further fragment the molecular ion. , Thereby generating fragment ions.
  • the generated molecular ions and fragment ions are pushed out of the ionization chamber under the combined action of the ion repulsor and the ion focusing lens group, and then leave the ion source after being focused.
  • the electron bombardment ionization source realizes the ionization of molecules through the collision between electrons and molecules, and through energy exchange. Therefore, the collision probability of electrons and molecules, or the size of the cross-sectional area of collisions between electrons and molecules, determines the ionization efficiency of the EI source.
  • the electrons move in a straight line along the initial velocity direction under the action of an electric field, as shown in Figure 2.
  • a magnetic field whose direction is parallel to the movement axis of the electron is added to the movement of the electron axis, so that the movement of the electron changes from a straight flight to a spiral movement around the axis, as shown in Figure 3. This increases the length of the flight path of the electron, thereby increasing the cross-sectional area of collision between the electron and the molecule, thereby increasing the ionization efficiency.
  • the electron energy is determined by the electric field between the electron repeller and the ionization chamber, or the cathode and anode.
  • the magnitude of electron energy has a high correlation with ionization efficiency, as shown in Figure 5. Therefore, in order to obtain sufficient ionization efficiency, the electron energy is usually about 70 eV, and the data in the standard library of the mass spectrometry EI source is all obtained using 70 eV.
  • embodiments of the present application provide an electron bombardment ionization source device, an ionization bombardment method, and a substance analysis method.
  • an electron bombardment ionization source device including an ionization chamber, a first filament, a first electron repulsion electrode, an electron receiving electrode, an ion repulsion electrode, an ion focusing lens group, and a magnet;
  • the electrons overflowing from the first filament after energization and heating move in a spiral motion under the force of the magnetic field direction. Under the action of the electric field perpendicular to the magnetic field direction, the radius of the spiral motion of the electrons increases, thereby increasing the actual electrons. Movement path, where the first filament works in a low ionization energy mode.
  • the radial acceleration electrode includes a positive electrode for radial acceleration of electrons and a negative electrode for radial acceleration of electrons that are symmetrically located up and down or front and rear of the first filament, and the first electron repeller and the electron radially
  • the accelerating negative electrode is integrated and has an L-shape.
  • the voltage value of the electron receiving electrode is the same as the voltage value of the first electron repeller, so that the electrons bounce back and forth between the electron receiving electrode and the first electron repeller, In turn, the actual movement path of the electron is increased.
  • an electron lens electrode is placed between the radial acceleration electrode and the ionization chamber, an electron transmission hole is opened in the middle of the electron lens electrode, and the center of the electron transmission hole is located on the electron flight reference axis on.
  • an electron bombardment ionization source device which includes an ionization chamber, a first filament, a first electron repeller, a second electron repeller, an ion repeller, an ion focusing lens group, and a magnet , Installing a second filament between the second electron repeller and the ionization chamber, wherein the second filament and the first filament are respectively symmetrically located on both sides of the ionization chamber;
  • the electrons overflowing from the first filament after being energized and heated move in a spiral motion under the force of the magnetic field direction.
  • the radius of the spiral motion of the electrons increases. Large, thereby increasing the actual movement path of the electrons, where the first filament works in a low ionization energy mode;
  • the first filament works in a low ionization energy mode
  • the second filament works in a normal ionization energy mode
  • the voltage value of the second electron repeller is the same as the voltage value of the first electron repeller, so that the electrons are repelled by the first electron repeller and the second electron repeller.
  • the poles bounce back and forth, thereby increasing the actual movement path of the electrons.
  • an electron lens electrode is placed between the radial acceleration electrode and the ionization chamber, an electron transmission hole is opened in the middle of the electron lens electrode, and the center of the electron transmission hole is located on the electron flight reference axis on.
  • an ionization bombardment method including:
  • the first filament emits electrons after being energized and generates heat. Under the action of the electric field formed between the first electron repeller and the ionization chamber, the electrons obtain corresponding energy, and the first filament works in a low ionization energy mode;
  • the electrons fly into the ionization chamber through the corresponding electron hole on the ionization chamber, and the electron moves in a spiral at a uniform speed under the force of the magnetic field, passes through the corresponding electron hole on the ionization chamber, and is received by the electron receiving electrode;
  • the electrons collide with the molecules of the measured substance injected during the movement of the ionization chamber; under the action of the electric field perpendicular to the direction of the magnetic field formed between the radial acceleration electrodes, the radius of the spiral of the electron movement increases, and then Increase the actual movement path of the electron.
  • an ionization bombardment method including:
  • the first filament When the first filament is turned on, the first filament emits electrons after being energized and heated. Under the action of the electric field formed between the first electron repeller and the ionization chamber, the electrons obtain corresponding energy;
  • the electrons fly into the ionization chamber through the corresponding electron holes on the ionization chamber, and the electrons move in a helix at a uniform speed under the force of the magnetic field, and finally hit the ionization chamber;
  • the electrons collide with the molecules of the measured substance injected during the movement of the ionization chamber; under the action of the electric field perpendicular to the direction of the magnetic field formed between the radial acceleration electrodes, the radius of the spiral of the electron movement increases;
  • the second filament When the second filament is turned on, the second filament emits electrons after being energized and heated. Under the action of the electric field formed between the second electron repeller and the ionization chamber, the electrons obtain corresponding energy;
  • the electrons fly into the ionization chamber through the corresponding electron hole on the ionization chamber, and the electrons move in a spiral at a uniform speed under the force of the magnetic field, and finally hit the ionization chamber;
  • the first filament works in a low ionization energy mode
  • the second filament works in a normal ionization energy mode
  • a material analysis method based on an electron bombardment ionization source device including:
  • the first filament emits electrons after being energized and generates heat. Under the action of the electric field formed between the first electron repeller and the ionization chamber, the electrons obtain corresponding energy, and the first filament works in soft ionization mode ;
  • the electrons fly into the ionization chamber through the corresponding electron hole on the ionization chamber, and collide with the injected molecules of the substance to be measured, and the molecular weight information of the substance to be measured can be obtained by soft ionization;
  • the second filament emits electrons after being energized and heated. Under the action of the electric field formed between the second electron repeller and the ionization chamber, the electrons obtain corresponding energy.
  • the second filament Working in hard ionization mode;
  • the electrons fly into the ionization chamber through the corresponding electron hole on the ionization chamber, and collide and ionize with the injected molecules of the measured substance, and the fragment ion information of the measured substance can be obtained by hard ionization;
  • the molecular structure of the measured substance is calculated.
  • the embodiments of the present application provide an electron bombardment ionization source device, an ionization bombardment method, and a material analysis method.
  • the molecular weight and fragment ion information of the measured substance can be obtained, and isomers can be distinguished, thereby realizing more accurate qualitative analysis.
  • Fig. 1 is a schematic structural diagram of an electron bombardment ionization source device with a cross-beam structure in the prior art
  • Fig. 2 is a schematic diagram of the electron movement route of the electron bombardment ionization source device in Fig. 1 in the absence of a magnetic field;
  • FIG. 3 is a schematic diagram of the electron bombardment ionization source device in FIG. 1 under the action of a magnetic field, the electrons making a spiral motion around an axis;
  • Figure 4 is a schematic diagram of the relationship between electron energy and ionization efficiency
  • FIG. 5 is a schematic diagram of the structure of an electron bombardment ionization source device according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of the structure of the ionization chamber in the electron bombardment ionization source device of the embodiment of the present application;
  • FIG. 7 is a schematic diagram of a partial structure of an electron bombardment ionization source device according to an embodiment of the present application.
  • FIG. 8 is a schematic diagram of a partial structure of an electron bombardment ionization source device according to an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a partial structure of an electron bombardment ionization source device according to an embodiment of the present application.
  • the embodiments of the present application provide an electron bombardment ionization source device that can improve the ionization efficiency, mainly by increasing the length of the electron movement path to increase the electrons.
  • the cross-sectional area of collision with the molecules of the object to be measured thereby improving the ionization efficiency, and further improving the sensitivity of the electron bombardment ionization source.
  • the electron bombardment ionization source working in the low energy mode it is of great significance.
  • FIG. 5 shows a schematic structural diagram of an electron bombardment ionization source device according to an embodiment of the present application.
  • the electron bombardment ionization source device provided by an embodiment of the present application includes an ionization chamber, a first filament, a first electron repeller, and an electron receiver. Pole, ion repeller, ion focusing lens group and magnet.
  • radial acceleration electrodes 612 are placed, and an electric field perpendicular to the direction of the magnetic field is formed between the radial acceleration electrodes 612;
  • the electrons overflowing from a filament move in a spiral under the force of the magnetic field. Under the action of the electric field perpendicular to the magnetic field, the radius of the spiral of electron movement increases, thereby increasing the actual movement path of the electrons.
  • the first filament works in a low ionization energy mode.
  • the electrons under the action of the magnetic field, the electrons not only move along the original axial and radial direction due to the angular force, but also rotate around the axis, which forms the electron spiral along the axis. movement.
  • the velocity of the electron along the axial direction is V ⁇
  • the velocity perpendicular to the direction of the magnetic field B is V ⁇ .
  • V ⁇ and V ⁇ determines the radius of the spiral, and V ⁇ determines the pitch of the spiral.
  • V ⁇ is determined by the electric field distribution between the electron repeller and the ionization chamber, and usually one end of the filament is directly connected to the electron repeller, thereby floating the voltage of the filament to the same as the electron repeller
  • the initial energy of an electron is determined by the electric field between the electron repeller and the ionization chamber, and it is usually tens of electron volts, such as 70 eV.
  • This energy determines the velocity V ⁇ of the electron parallel to the direction of the magnetic field B, and the velocity perpendicular to the direction of the magnetic field is determined by the initial energy when the electrons overflow the surface of the filament, usually only 0.1eV.
  • a certain amount of energy is applied to the electron in the direction of the vertical magnetic field to increase the speed of the electron in the direction of the vertical magnetic field, so that when the electron moves in a spiral in the magnetic field, the radius of the spiral is increased. , Thereby increasing the length of the total movement path of the electron, thereby increasing the cross-sectional area of collision between the electron and the molecule, thereby improving the ionization efficiency.
  • the specific electron bombardment ionization source device can be seen in Figure 5.
  • the two magnets 610 are symmetrically distributed on the outer side of the first electron repulsor 603 and the electron receiving electrode 607 in the order of opposite polarities along the center axis of the ionization chamber 611 to form a magnetic field direction. It is a stable magnetic field of N to S and an intensity of B, and the direction of the magnetic field is parallel to the electron flight reference axis 604.
  • the first filament 602 is located inside the first electron repeller 603 and outside the ionization chamber 601.
  • the first filament 602 is usually a small section made of cathode materials with a relatively high emission current density, such as pure tungsten cathodes, thorium tungsten cathodes, and other oxide cathodes.
  • the shape of the first filament 602 may be filament or ribbon.
  • a voltage with a certain pressure difference is applied to both ends of the first filament 602, so that ampere-level current flows through the first filament 602.
  • the first filament 602 generates heat and reaches a temperature of thousands of degrees Celsius. The hot electrons will exceed Its work function leaves the surface of the first filament 602, thereby emitting electrons.
  • a certain electric field is applied between the first electron repeller 603 and the ionization chamber 601, so that the overflowing electrons can move in the direction of the ionization chamber along the direction of the electric field.
  • the first filament 602 and the first electron repeller 603 are short-circuited at the potential, so that the potential difference between the first electron repeller 603 and the ionization chamber 601 is almost equal to the emission energy of the electrons.
  • the energy is very small, usually only 0.1 eV. For example, if the ionization chamber 601 is set to zero potential and the first electron repellent 603 is applied with a voltage of -70V, the electron emission energy is 70eV.
  • the ionization chamber 601 is provided with an electron entrance hole 701, an electron exit hole 702, a sample molecule injection hole 703, and an ion ejection port 704.
  • the electron entrance hole 701 and the electron exit hole 702 have the same shape, which can be a round hole or a rectangular hole, and the long side of the rectangular hole corresponds to the shape of the first filament 602 filament.
  • the central axis formed by the center points of the electron entrance hole 701 and the electron exit hole 702 is coaxial with the electron flight reference axis 604.
  • the center point of the sample molecule injection hole 703 is orthogonal to the electron flight reference axis 604 and the center axis 611 of the ionization chamber.
  • the above is the same structure as the current conventional electron bombardment ionization source device.
  • the difference is that the first electron repeller 603 is close to the inside of the ionization chamber 601, and the electrons are placed above and below or before and after the first filament 602 to accelerate radially.
  • the positive electrode 605 and the electron radial acceleration negative electrode 606, that is, the radial acceleration electrode 612, the electron radial acceleration positive electrode 605 and the electron radial acceleration negative electrode 606 make the electrons overflowing from the first filament 602 subject to the radial direction perpendicular to the magnetic field.
  • the effect of the electric field causes V ⁇ to increase, so that the radius R of the helix of the electron moving around the axis increases, while the pitch remains unchanged, which makes the actual movement path of the electron increase, so that the cross-sectional area of the collision between the electron and the molecule is corresponding Increase, so that the ionization efficiency is improved.
  • the voltage value of the electron receiving electrode is the same as the voltage value of the first electron repeller, so that the electrons bounce back and forth between the electron receiving electrode and the first electron repeller, thereby increasing the actual value of the electrons. Movement path.
  • the voltage of the electron receiving electrode 607 and the voltage of the first electron repeller 603 are set to the same value, so that the electron receiving electrode 607 will change from the receiving function to the electron rebound function, and the electrons will bounce back to the ionization chamber. 601.
  • the electrons will bounce back and forth between the electron receiving electrode 607 and the first electron repeller 603, until finally hitting the ionization chamber 601 and disappearing.
  • the rebound of electrons doubles the path of movement of electrons, so that the cross-sectional area of collision between electrons and molecules is correspondingly increased, thereby increasing the ionization efficiency.
  • the same ionization efficiency can be obtained with a lower emission current, which will double the life of the filament and greatly increase the reliability of the system.
  • the ions ionized by electrons (the analyte molecules are ionized into ions after colliding with the electrons) are expelled from the ion source under the combined action of the ion repeller 608 and the ion focusing lens group 609. It is sent to the ion transmission component or mass analyzer for subsequent transmission and analysis.
  • the first electron repeller 603 and the electron radial acceleration negative electrode are integrated 606 and are L-shaped.
  • the first electron repeller 603 and the electron radial acceleration negative electrode 606 are L-shaped, which can be understood as the first electron repeller 603 and the electron radial acceleration negative electrode in FIG.
  • the electrodes 606 are fixed as a whole, one part of which functions as the electron repeller 602, and the other part functions as the negative electrode 606 for radial acceleration of electrons.
  • a radial acceleration electric field is formed between the electron radial acceleration positive electrode 605 and the electron radial negative electrode 606, so that the electrons overflowing from the first filament 602 are subjected to an electric field perpendicular to the radial direction of the magnetic field, so that V ⁇ increases.
  • the spiral radius R of the electrons moving around the axis is increased, while the pitch remains unchanged, which increases the actual movement path of the electrons, so that the collision cross-sectional area of the electrons and molecules is correspondingly increased, thereby improving the ionization efficiency.
  • an electron lens electrode 901 is placed between the radial acceleration electrode and the ionization chamber.
  • An electron transmission hole 902 is opened in the middle of the electron lens electrode 901, and the center of the electron transmission hole 902 is located on the electronic flight reference axis.
  • the electron lens electrode 901 can play a role in focusing electrons.
  • the electron lens electrode 901 is located between the radial acceleration electrode and the ionization chamber 601, and an electron transmission hole 902 is opened in the middle of the electron lens electrode 901.
  • the center of the electron transmission hole 902 is located in the electron flight.
  • an electron lens electrode 901 is added between the radial acceleration electrode 612 formed by the electron radial acceleration negative electrode 606 and the electron radial acceleration positive electrode 605 and between the ionization chamber 601, and the electron
  • the potential difference between the lens electrode 901 and the electron radial acceleration negative electrode 606 is greater than the potential difference between the ionization chamber 601 and the electron radial acceleration negative electrode 605, so that the electrons can accelerate away from the surface of the first filament 602 at a higher speed Therefore, the formation of space charge is avoided.
  • the electrons After passing through the electron lens electrode 901, the electrons are decelerated between the electron lens electrode 901 and the ionization chamber 601, and return to the radial acceleration of the electrons between the negative electrode 606 and the ionization chamber 601. The energy corresponding to the potential difference.
  • the electron bombardment ionization source device includes an ionization chamber 601, a first filament 602, a first electron repeller 603, and a second electron repeller.
  • the repeller 1006, the ion repeller 608, the ion focusing lens group 609, and the magnet 610 are installed with a second filament 1002 between the electron receiving electrode 607 and the ionization chamber 601, wherein the second filament 1002 and the first filament 602 are located symmetrically Both sides of the ionization chamber 601.
  • the electrons overflowing from the first filament 602 after being energized and heated move in a spiral line under the force of the magnetic field direction. Under the action of an electric field perpendicular to the direction of the magnetic field, the electrons move in the spiral line. The radius increases, thereby increasing the actual movement path of the electrons, wherein the first filament 602 works in a low ionization energy mode;
  • the first filament 602 works in a low ionization energy mode
  • the second filament 1002 works in a normal ionization energy mode.
  • the first filament 602 works in a low ionization energy mode, such as an ionization energy of 10-30 eV
  • the second filament 1002 works in a conventional ionization energy mode, such as 70 eV.
  • a first electron repeller 603 on the side of the first filament 602, a first electron repeller 603, a radial acceleration electrode (including a positive electrode for radial acceleration of electrons and a negative electrode for radial acceleration of electrons) and an electron lens electrode 901 are installed.
  • the second electron repeller 1006 is installed, and the radial acceleration electrode and the electron lens electrode are not installed. According to different application needs, these two modes can be switched back and forth.
  • the first electron repeller 603 is a low ionization energy electron repeller
  • the second electron repeller 1006 is a conventional ionization energy electron repeller.
  • the 70eV conventional ionization mode is used for analysis, and the electrons overflow from the second filament 1002 Then, under the action of the electric field of the second electron repeller 1006 and the ionization chamber 601, it accelerates to the ionization chamber 601, passes through the electron exit hole 702, enters the ionization chamber 601, and then interacts with the sample molecule injection hole 703. The analyte molecule undergoes collision ionization.
  • the molecular ions and fragment ions generated after ionization leave the ion source under the combined action of the ion repeller 608 and the ion focusing lens group 609, and then the mass analyzer and detector complete the mass analysis and detection. Qualitative and quantitative analysis can be achieved through the characteristic ions of each substance.
  • the low ionization energy mode is adopted. After the electrons overflow from the first filament 602, they are accelerated to the ionization chamber 601 under the action of the electric field of the first electron repeller 603 and the electron lens electrode 901. During the flight, they are pushed by the radial acceleration electrode and the first electron.
  • the radial acceleration electric field of the repeller 603 generates radial velocity, and then moves in the magnetic field of the magnet 610 around the electron flight reference axis 604 toward the ionization chamber 601, passes through the electron entrance hole 701, and then enters the ionization chamber 601. Then, collision ionization occurs with the analyte molecules entering from the sample molecule injection hole 703. By adjusting the appropriate ionization energy, the analyte is free of fragment ions.
  • the molecular ions generated after ionization leave the ion source under the combined action of the ion repeller 608 and the ion focusing lens group 609, and then are mass analyzed and detected by the mass analyzer and detector. Qualitative and quantitative analysis can be achieved by passing molecular ion peaks generated after ionization.
  • the electron bombardment ionization source device provided in Figure 9 can work in two modes, that is, the filament works in the low ionization energy working mode and the conventional ionization energy working mode. It can be understood that the electron bombardment ionization source device in Figure 9 can be realized at the same time The function of the electron bombardment ionization source device in FIG. 5 and the function of the conventional electron bombardment ionization source device in FIG. 1.
  • the ionization efficiency of the electron bombardment ionization source device is directly related to the collision cross-sectional area.
  • the size of the collision cross-sectional area is related to the electron energy. As the electron energy decreases, the collision cross-sectional area also decreases. Therefore, when the electron bombardment ionization source device works in a low ionization energy mode, its ionization efficiency is greatly reduced. Therefore, the embodiments of this application make full use of the principle that electrons move in a spiral along an axis under the action of a magnetic field.
  • the radius of the spiral is proportional to the electron velocity in the vertical direction of the magnetic field (that is, the electron radial velocity direction).
  • the pitch is proportional to the velocity of the electron along the direction parallel to the magnetic field (ie, the direction of the axial velocity of the electron).
  • the electron energy determines the axial velocity of the electron, but the effect on the radial velocity of the electron is limited.
  • the embodiment of this application adds an additional electric field in the vertical direction of the magnetic field, so that the radial velocity of the electron is greatly increased. Therefore, without changing the electron Under the premise of energy, the radius of the spiral of the electron's movement around the axis is increased, while the pitch of the movement around the axis is unchanged, so that the entire movement path of the electron is lengthened.
  • an electron bombardment method based on an electron bombardment ionization source includes:
  • the first filament After the first filament is energized and generates heat, electrons are released. Under the action of the electric field formed between the first electron repeller and the ionization chamber, the electrons obtain corresponding energy, and the first filament works in a low ionization energy mode;
  • the electrons fly into the ionization chamber through the corresponding electron hole on the ionization chamber, and the electron moves in a spiral at a uniform speed under the force of the magnetic field, passes through the corresponding electron hole on the ionization chamber, and is received by the electron receiving electrode;
  • the electrons collide with the molecules of the measured substance injected during the movement of the ionization chamber; under the action of the electric field perpendicular to the direction of the magnetic field formed between the radial acceleration electrodes, the radius of the spiral of the electron movement increases, and then Increase the actual movement path of the electron.
  • the embodiment of the present application is an ionization bombardment method based on the electron bombardment ionization source device in FIG. 5, wherein the specific collision process between the electron and the target molecule can be referred to the foregoing description, and will not be omitted here.
  • it is mainly by applying an electric field in the vertical direction of the magnetic field. Under the action of the electric field perpendicular to the direction of the magnetic field, the radius of the spiral of electron movement is increased, thereby increasing the actual movement path of the electron.
  • an electron bombardment method based on an electron bombardment ionization source includes:
  • the first filament When the first filament is turned on, the first filament emits electrons after being energized and heated. Under the action of the electric field formed between the first electron repeller and the ionization chamber, the electrons obtain corresponding energy;
  • the electrons fly into the ionization chamber through the corresponding electron holes on the ionization chamber, and the electrons move in a helix at a uniform speed under the force of the magnetic field, and finally hit the ionization chamber;
  • the electrons collide with the molecules of the measured substance injected during the movement of the ionization chamber; under the action of the electric field perpendicular to the direction of the magnetic field formed between the radial acceleration electrodes, the radius of the spiral of the electron movement increases;
  • the second filament When the second filament is turned on, the second filament emits electrons after being energized and heated. Under the action of the electric field formed between the second electron repeller and the ionization chamber, the electrons obtain corresponding energy;
  • the electrons fly into the ionization chamber through the corresponding electron hole on the ionization chamber, and the electrons move in a spiral at a uniform speed under the force of the magnetic field, and finally hit the ionization chamber;
  • the first filament works in a low ionization energy mode
  • the second filament works in a normal ionization energy mode
  • the embodiment of the present application is an ionization bombardment method based on the electron bombardment ionization source device in FIG. 9, wherein the electron bombardment ionization source device of the embodiment of the present application can realize ionization bombardment in two working modes, each The collision process between the electrons and the molecules of the test object in this working mode can be referred to the foregoing description, and will not be repeated here.
  • a material analysis method based on an electron bombardment ionization source device including:
  • the first filament emits electrons after being energized and generates heat. Under the action of the electric field formed between the first electron repeller and the ionization chamber, the electrons obtain corresponding energy, and the first filament works in soft ionization mode;
  • the electrons fly into the ionization chamber through the corresponding electron hole on the ionization chamber, and collide with the injected molecules of the substance to be measured, and the molecular weight information of the substance to be measured can be obtained by soft ionization;
  • the second filament emits electrons after being energized and heated. Under the action of the electric field formed between the second electron repeller and the ionization chamber, the electrons obtain corresponding energy.
  • the second filament Working in hard ionization mode;
  • the electrons fly into the ionization chamber through the corresponding electron hole on the ionization chamber, and collide and ionize with the injected molecules of the measured substance, and the fragment ion information of the measured substance can be obtained by hard ionization;
  • the molecular structure of the measured substance is calculated.
  • one filament works in the soft ionization mode
  • the other filament works in the hard ionization mode (70 eV).
  • the first filament emits electrons after being energized and heated.
  • the electrons fly into the ionization chamber through the corresponding electron holes on the ionization chamber, collide with the injected molecules of the substance to be measured, and obtain the molecular weight information after soft ionization.
  • the molecular weight information only the substance molecule of the tested substance can be obtained, but there may be isomers with the same molecular weight, but the fragments will be different if the molecular structure is different, such as the abundance of fragment ions.
  • the second filament works in hard ionization mode.
  • the second filament emits electrons after being energized and generates heat.
  • the electrons fly into the ionization chamber through the corresponding electron holes on the ionization chamber.
  • the molecules of the measured substance collide, and the fragment ion information of the measured substance is obtained.
  • the two filaments work in the soft ionization mode and the hard ionization mode respectively, and the same differentiation can be achieved.
  • the structure is distinguished, so as to avoid the problem that the soft ionization mode cannot distinguish the isomers.
  • the tested substance can be a single substance, or it can be a variety of different mixed substances.
  • a single substance means that the molecular weight information of the substance is the same and the structure is the same; if the molecular weight of the two substances is the same but the molecular structure is different, Then these two substances are two different substances. Due to the phenomenon of isomers between substances, it is impossible to determine the molecular structure of the substance to be tested based on only the molecular weight information of the substance.
  • the first filament is used to soft ionize the substance to be measured to obtain the molecular weight information of the substance to be measured; then the second filament is used to perform hard ionization of the substance to be measured to obtain fragment ion information of the substance to be measured.
  • the molecular structure of the measured substance can be analyzed. Regardless of whether the substance to be tested is a single substance or a mixture of multiple substances, the soft ionization and hard ionization methods of the embodiments of the present application can be used to analyze the molecular structure of each substance.
  • the embodiment of the present application provides an electron bombardment ionization source device, an ionization bombardment method, and a material analysis method.
  • the radial acceleration electric field used will increase the radius of the electron spiral around the axis, so that the electron energy is not changed. , So that the electron's path of movement is lengthened, so the collision cross-sectional area is increased, so that the ionization efficiency is improved.
  • Using the electron bombardment ionization source device provided in the embodiments of the application for ionization bombardment will enable the electron bombardment ionization source device to obtain the same ionization efficiency as the traditional electron bombardment ionization source device in the low ionization energy mode, so that the ionization energy is reduced. The sensitivity is still not reduced. Therefore, the electron bombardment ionization source device in the low ionization energy working mode can be directly used for the direct analysis of complex samples without relying on separation methods such as chromatography, and the volume and power consumption of the instrument will become smaller.
  • the same voltage as the electron repeller is applied.
  • the electrons fly through the ionization chamber to the electron repeller, the electrons will be bounced back to the ionization chamber due to the reverse force of the electric field. Makes the length of the electron movement route further increased, thereby increasing the ionization efficiency;

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Abstract

一种电子轰击电离源装置、电离轰击方法及物质分析方法，装置包括：在第一电子推斥极（603）靠近电离室（601）的内侧、在第一灯丝（602）的上下或者前后，放置径向加速电极（612），在径向加速电极（612）之间形成垂直于磁场方向的电场；通电发热后的第一灯丝（602）溢出的电子在磁场方向的作用力下呈螺旋线运动，其中，在垂直于磁场方向的电场的作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径，增大了电子与被测物分子的碰撞截面积，进而提高了离子源的电离效率。

Description

一种电子轰击电离源装置、电离轰击方法及物质分析方法 技术领域
本申请属于电子技术领域，尤其涉及一种电子轰击电离源装置、电离轰击方法及物质分析方法。
背景技术
电子轰击电离源(EI)是一种传统的质谱仪用离子源方法。它利用热电子发射，并通过一定强度的电场加速使其具有一定的能量，然后与被分析物的分子进行碰撞，通过能量交换，使得分子电离成分子离子，有的分子离子会因为获得了较多的能量，而会进一步碎裂成为碎片离子。这些分子离子和碎片离子作为分子的指纹图谱，可以作为判断分子结构的依据，并成为了一种标准方法。这些分子的指纹图谱更是被建立成了标准的EI源标准质谱图数据库，而被广泛的应用，如NIST谱库，willey质谱数据库等。
电子轰击电离源作为应用最广泛的一种质谱仪离子源，最常用的结构形式为交叉束结构，如图1所示，通常由电离室、灯丝、电子推斥极、电子接收极、离子推斥极、离子聚焦透镜组，以及磁铁等组成。灯丝通常由发射电流密度大的阴极材料制成，通上足够的电流后灯发热，然后释放出热电子。在电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，然后通过电离室上对应的电子孔飞入电离室，电离室内部通常为一均匀电场，因此，电子保持恒定速度继续飞行，然后穿过电离室上相应的电子孔之后，被电子接收极接收。气体分子流以与电子运动的方向相垂直正交的方向通入电离室，并在电离室中心碰撞。电子通过碰撞的方式，将能量传给分子，当电子的能量超过分子的电离能时，分子丢失一个电子，从而带上正电，成为分子离子，而过多的能量会使分子离子进一步碎裂，从而产生碎片离子。产生的分子离子和碎片离子在离子推斥极和离子聚焦透镜组的共同作用下，被推出电离室，然后聚焦后离开离子源。
电子轰击电离源是通过电子与分子之间的碰撞，通过能量交换来实现分子电离的。因此，电子与分子的碰撞几率，或者说电子与分子的碰撞截 面积的大小，就决定了EI源的电离效率。在无磁场作用下，电子在电场作用下，沿着初速度方向做直线运动，如图2所示。为了提高电子的运动路径，在电子轴线运动上，增加一个磁场方向与电子运动轴平行的磁场，使得电子的运动由直线飞行变成以螺旋线绕轴运动，如图3所示。这就使得电子的飞行路径长度增加，从而使得电子与分子之间的碰撞截面积增加，进而提高电离效率。
EI源中，电子能量由电子推斥极和电离室，或阴极和阳极之间的电场决定。电子能量的大小，与电离效率具有高度的相关性，如图5所示。因此，为了获得足够的电离效率，通常电子能量取70eV左右，质谱EI源标准谱库的数据均是采用70eV获得。
随着现场快速检测需求的日益扩大，各类质谱仪也纷纷开始进入这一领域。但是，由于EI源电离能过大，生成的离子碎片过多，不同物质之间就不可避免发生碎片离子的重叠，这使得EI源单质谱的应用受到限制。于是，一种方式是采用快速色谱与EI源质谱串联来解决EI源电离碎片重叠的问题，另一种方式就是采用软电离技术，如紫外光电离等离子源技术。
但是对于色谱-质谱联用方案来说，色谱分离需要时间，即使采用快速色谱，其分离时间也都是以分钟作为单位进行量化的，这对于追求分析速度的应用场合来说，显然不是一个最佳的方案。紫外光电离离子源技术因为电离能低，因此几乎不产生碎片，对于快速分析来说具有一定的优势，但是，相比于EI源，它的电离效率较低，而且其电离能恒定，无法对电离能高的分子进行电离。因此，其应用也受到一定的限制。
发明内容
为克服上述现有问题或者至少部分地解决上述问题，本申请实施例提供一种电子轰击电离源装置、电离轰击方法及物质分析方法。
根据本申请实施例的第一方面，提供一种电子轰击电离源装置，包括电离室、第一灯丝、第一电子推斥极、电子接收极、离子推斥极、离子聚焦透镜组和磁铁；
在所述第一电子推斥极靠近电离室的内侧、在第一灯丝的上下或者前后，放置径向加速电极，在径向加速电极之间形成垂直于磁场方向的电场；
通电发热后的第一灯丝溢出的电子在磁场方向的作用力下呈螺旋线 运动，其中，在垂直于磁场方向的电场的作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径，其中，第一灯丝在低电离能模式下工作。
在上述技术方案的基础上，本申请还可以作如下改进。
可选的，所述径向加速电极包括对称位于所述第一灯丝上下或前后的电子径向加速正电极和电子径向加速负电极，所述第一电子推斥极和所述电子径向加速负电极为一体，且呈L型。
可选的，所述电子接收极的电压值与所述第一电子推斥极的电压值相同，使得所述电子在所述电子接收极和所述第一电子推斥极之间来回反弹，进而增加电子的实际运动路径。
可选的，在所述径向加速电极和所述电离室之间放置电子透镜电极，所述电子透镜电极中间位置开设有电子透过孔，所述电子透过孔的中心位于电子飞行参考轴上。
根据本申请实施例第二方面提供一种电子轰击电离源装置，包括电离室、第一灯丝、第一电子推斥极、第二电子推斥极、离子推斥极、离子聚焦透镜组和磁铁，在所述第二电子推斥极和所述电离室之间安装第二灯丝，其中，所述第二灯丝和所述第一灯丝分别对称位于所述电离室的两侧；
在所述第一电子推斥极靠近电离室的内侧、在第一灯丝的上下或者前后，放置径向加速电极，在径向加速电极之间形成垂直于磁场方向的电场；
当打开第一灯丝时，通电发热后的第一灯丝溢出的电子在磁场方向的作用力下呈螺旋线运动，其中，在垂直于磁场方向的电场的作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径，其中，第一灯丝在低电离能模式下工作；
其中，第一灯丝在低电离能模式下工作，第二灯丝在常规电离能模式下工作。
可选的，所述第二电子推斥极的电压值与所述第一电子推斥极的电压值相同，使得所述电子在所述第一电子推斥极和所述第二电子推斥极之间来回反弹，进而增加电子的实际运动路径。
可选的，在所述径向加速电极和所述电离室之间放置电子透镜电极，所述电子透镜电极中间位置开设有电子透过孔，所述电子透过孔的中心位 于电子飞行参考轴上。
根据本申请实施例的第三个方面，提供一种电离轰击方法，包括：
第一灯丝通电发热后释放出电子，在第一电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，所述第一灯丝工作在低电离能模式；
电子通过电离室上对应的电子孔飞入电离室，电子在磁场方向的作用力下呈螺旋线匀速运动，穿过电离室上相应的电子孔之后，被电子接收极接收；
其中，电子在电离室运动的过程中，与注入的被测物质的分子碰撞；在径向加速电极之间形成的垂直于磁场方向的电场作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径。
根据本申请的第四方面，提供一种电离轰击方法，包括：
当打开第一灯丝时，第一灯丝通电发热后释放出电子，在第一电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量；
电子通过电离室上对应的电子孔飞入电离室，电子在磁场方向的作用力下螺旋线匀速运动，最终打在电离室上；
其中，电子在电离室运动的过程中，与注入的被测物质的分子碰撞；在径向加速电极之间形成的垂直于磁场方向的电场作用下，电子运动的螺旋线的半径增大；
或者，
当打开第二灯丝时，第二灯丝通电发热后释放出电子，在第二电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量；
电子通过电离室上对应的电子孔飞入电离室，电子在磁场方向的作用力下呈螺旋线匀速运动，最终打在电离室上；
其中，第一灯丝在低电离能模式下工作，第二灯丝在常规电离能模式下工作。
根据本申请的第五方面，提供了一种基于电子轰击电离源装置的物质分析方法，包括：
打开第一灯丝，第一灯丝通电发热后释放出电子，在第一电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，所述第一灯丝 工作在软电离模式；
电子通过电离室上对应的电子孔飞入电离室，与注入的被测物质的分子发生碰撞电离，由此软电离得到被测物质的分子量信息；
关闭第一灯丝，打开第二灯丝，第二灯丝通电发热后释放出电子，在第二电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，所述第二灯丝工作在硬电离模式；
电子通过电离室上对应的电子孔飞入电离室，与注入的被测物质的分子发生碰撞电离，由此硬电离得到被测物质的碎片离子信息；
根据被测物质的分子量信息和碎片离子信息，计算出被测物质的分子结构。
本申请实施例提供一种电子轰击电离源装置、电离轰击方法及物质分析方法，通过增加与电子运动参考轴线垂直的电场，在电场的作用下，电子呈螺旋线运行的半径增大，进而增加了电子在电离室内的实际运行路径，增大了电子与被测物分子的碰撞截面积，进而提高了离子源的电离效率；
使用两个灯丝分别工作在软电离模式和硬电离模式，得到被测物质的分子量和碎片离子信息，可以区分同分异构体，从而实现更准确的定性分析。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作一简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为现有技术中的交叉束结构的电子轰击电离源装置结构示意图；
图2为图1中的电子轰击电离源装置在无磁场情况下电子运动路线示意图；
图3为图1中的电子轰击电离源装置在磁场作用下，电子绕轴做螺旋线运动的示意图；
图4是电子能量与电离效率之间的关系示意图；
图5是本申请实施例的电子轰击电离源装置结构示意图；
图6是本申请实施例的电子轰击电离源装置中电离室的结构示意图；
图7是本申请实施例的电子轰击电离源装置的局部结构示意图；
图8是本申请实施例的电子轰击电离源装置的局部结构示意图；
图9是本申请实施例的电子轰击电离源装置的局部结构示意图。
附图中，各标号所代表的的部件名称如下：
601、电离室，602、第一灯丝，603、第一电子推斥极，604、电子飞行参考轴，605、电子径向加速正电极，606、电子径向加速负电极，607、电子接收极，608、离子推斥极，609、离子聚焦透镜组，610、磁铁，611、电离室中心轴，612、径向加速电极，701、电子入射孔，702、电子出射孔，703、样品分子注入孔，704、离子飞行轴，901、电子透镜电极，902、电子透过孔，1002、第二灯丝，1006、第二电子推斥极。
具体实施方式
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作一简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
针对现有技术中电子轰击电离源装置的电离效率低下的缺点，本申请实施例提供了一种能够提高电离效率的电子轰击电离源装置，主要是通过增加电子的运动路线的长度，来增加电子与被测物分子之间的碰撞截面积，从而提高电离效率，进而提高电子轰击电离源的灵敏度。尤其对于低能量模式工作的电子轰击电离源，具有特别重要的意义，可以使得工作在低能量模式下的电子轰击电离源，能够获得与传统硬电离(70eV)一样甚至更高的电离效率，从而可以发展出软电离EI源质谱系统，用于现场快速检测需求，并且保持其较高的灵敏度。
可参见图5，示出了本申请实施例的电子轰击电离源装置的结构示意图，本申请实施例提供的电子轰击电离源装置包括电离室、第一灯丝、第一电子推斥极、电子接收极、离子推斥极、离子聚焦透镜组和磁铁。在第一电子推斥极靠近电离室的内侧、在第一灯丝的上下或者前后，放置径向加速电极612，在径向加速电极612之间形成垂直于磁场方向的电场；通电发热后的第一灯丝溢出的电子在磁场方向的作用力下呈螺旋线运动，其中，在垂直于磁场方向的电场的作用下，电子运动的螺旋线的半径增大， 进而增加电子的实际运动路径，其中，第一灯丝在低电离能模式下工作。
可以理解的是，电子在磁场作用下，因受到角向力的作用，电子不仅沿着原有的轴向和径向运动，同时还要绕轴旋转，这就形成了电子沿轴做螺旋线运动。如图3所示，电子沿轴向的速度为V ∥，垂直于磁场B方向的速度为V ⊥。
电子螺旋线运动的半径R，满足如下方程：
Figure PCTCN2020094906-appb-000001
电子螺旋线运动的螺距l，满足如下方程：
Figure PCTCN2020094906-appb-000002
可见，电子运动螺旋线的总长度由V ∥和V ⊥决定，其中V ⊥决定螺旋线的半径，V ∥决定螺旋线的螺距。
其中，V ∥由电子推斥极和电离室之间的电场分布决定，并且通常灯丝的一端会和电子推斥极直接连接到一起，从而将灯丝的电压浮置到与电子推斥极相同的电位上，因此，电子的初始能量就由电子推斥极和电离室之间的电场决定，通常为几十电子伏特，比如70eV。这一能量决定了电子平行于磁场B方向的速度V ∥，而垂直于磁场方向的速度则是由电子溢出灯丝表面时候的初始能量决定，通常仅0.1eV。
因此，本申请实施例在垂直磁场的方向上，给电子施加一定的能量，以增加电子在垂直磁场方向上的速度，从而使得电子在磁场中做螺旋线运动的时候，使得螺旋线的半径增加，从而使得电子的总运动路线长度增加，进而增加电子与分子之间的碰撞截面积，从而提高电离效率。
具体的电子轰击电离源装置可参见图5，2个磁铁610按照极性相反的顺序以电离室中心轴611对称分布于第一电子推斥极603和电子接收极607的外侧，构成一个磁场方向为N到S、并且强度为B的稳定磁场，并且使磁场方向与电子飞行参考轴604平行。第一灯丝602位于第一电子推斥极603的内侧、电离室601的外侧。第一灯丝602通常为一小段由发射电流密度较大的阴极材料制成，如纯钨阴极、钍钨阴极，以及其它一些氧化物阴极等，其形状可以是丝状，也可以是带状。在第一灯丝602两端加上具有一定压差的电压，以使安培级的电流通过第一灯丝602，第一灯丝602由此发热，并达到上千摄氏度的温度，热电子就会因超出其逸出功而 离开第一灯丝602表面，从而发射出电子。在第一电子推斥极603和电离室601之间施加一定的电场，就可以让溢出的电子沿着电场方向向电离室方向运动。通常将第一灯丝602和第一电子推斥极603在电位上短接，这样第一电子推斥极603和电离室601之间的电位差几乎等于电子的发射能量，其中，溢出电子的初始能量非常小，通常仅0.1eV。比如将电离室601设为零电位，第一电子推斥极603施加-70V的电压，则电子的发射能量就是70eV。
如图6所示，在电离室601上，开有电子入射孔701、电子出射孔702、样品分子注入孔703、离子逐出口704。电子入射孔701和电子出射孔702的形状一致，可以是圆孔，也可以是矩形孔，矩形孔的长边与第一灯丝602灯丝的形状相对应。电子入射孔701和电子出射孔702的孔中心点形成的中心轴与电子飞行参考轴604同轴。样品分子注入孔703的孔中心点与电子飞行参考轴604和电离室中心轴611正交。
以上均与目前常规的电子轰击电离源装置的结构相同，不同的是，在第一电子推斥极603靠近电离室601的内侧，在第一灯丝602的上下或者前后，分别放置电子径向加速正电极605和电子径向加速负电极606，即径向加速电极612，电子径向加速正电极605和电子径向加速负电极606使得从第一灯丝602上溢出的电子受到垂直于磁场径向上的电场作用而使得V ⊥增加，从而使得电子绕轴运动的螺旋线半径R增大，而螺距仍然保持不变，这就使得电子的实际运动路径增加，这样电子与分子的碰撞截面积就相应提高，从而使得电离效率得到提升。
作为一个可选的实施例中，电子接收极的电压值与第一电子推斥极的电压值相同，使得电子在电子接收极和第一电子推斥极之间来回反弹，进而增加电子的实际运动路径。
可以理解的是，将电子接收极607的电压和第一电子推斥极603的电压设置为相同值，这样，电子接收极607就会由接收功能变为电子反弹功能，将电子反弹回电离室601。电子就会在电子接收极607和第一电子推斥极603之间来回反弹，直到最后打到电离室601上消失。电子的反弹使得电子的运动路径成倍增加，这样电子与分子的碰撞截面积就相应提高，从而使得电离效率得到提高。另一方面，采用电子反弹的方式，可以用更 低的发射电流而获得同样的电离效率，这将使得灯丝的寿命得以成倍延长，大大增加系统的可靠性。
其中，在电离室601内部，被电子电离的离子(被测物分子与电子碰撞后，被电离成离子)在离子推斥极608和离子聚焦透镜组609的共同作用下被逐出离子源，送入离子传输部件或质量分析器以进行后续的传输和分析。
作为一个可选的实施例，第一电子推斥极603和电子径向加速负电极为一体606，且呈L型。
可以理解的是，如图7中，第一电子推斥极603和电子径向加速负电极606呈L型，可以理解为将图5中的第一电子推斥极603和电子径向加速负电极606固定为一体，其中一部分充当电子推斥极602的功能，另一部分充当电子径向加速负电极606的功能。电子径向加速正电极605与电子径向负电极606之间形成径向加速电场，使得从第一灯丝602上溢出的电子受到垂直于磁场径向上的电场作用而使得V ⊥增加。从而使得电子绕轴运动的螺旋线半径R增大，而螺距仍然保持不变，这就使得电子的实际运动路径增加，这样电子与分子的碰撞截面积就相应提高，从而使得电离效率得到提升。
作为一个可选的实施例，在径向加速电极和电离室之间放置电子透镜电极901，电子透镜电极901中间位置开设有电子透过孔902，电子透过孔902的中心位于电子飞行参考轴604上，其中，电子透镜电极901可以起到对电子聚焦的作用。
可以理解的是，如图8所示，电子透镜电极901位于径向加速电极和电离室601之间，电子透镜电极901中间开有电子透过孔902，电子透过孔902的圆心位于电子飞行参考轴604上。当轰击电离源的电离能仅有10-30eV的时候，也即轰击电离源工作在低能量模式时，较低的电场作用使得电子的飞行速度低于第一灯丝602表面溢出的电子的速度，结果电子会在第一灯丝602和电离室601之间累积形成空间电荷，并由此形成虚电位，从而影响电子的进一步发射。为此，本申请实施例中，在电子径向加速负电极606和电子径向加速正电极605形成的径向加速电极612之间和电离室601之间，增加电子透镜电极901，并使电子透镜电极901和电子 径向加速负电极606之间的电位差大于电离室601和电子径向加速负电极605之间的电位差，从而使得电子能够以更高的速度加速离开第一灯丝602表面，从而避免了空间电荷的形成，电子穿过电子透镜电极901之后，在电子透镜电极901和电离室601之间被减速，并回到与电子径向加速负电极606和电离室601之间的电位差对应的能量。
参见图9，提供了本申请实施例的具有双灯丝结构的电子轰击电离源装置，该电子轰击电离源装置包括电离室601、第一灯丝602、第一电子推斥极603、第二电子推斥极1006、离子推斥极608、离子聚焦透镜组609和磁铁610，在电子接收极607和电离室601之间安装第二灯丝1002，其中，第二灯丝1002和第一灯丝602分别对称位于电离室601的两侧。在第一电子推斥极603靠近电离室601的内侧、在第一灯丝602的上下或者前后，放置径向加速电极612，在径向加速电极612之间形成垂直于磁场方向的电场；
当打开第一灯丝602时，通电发热后的第一灯丝602溢出的电子在磁场方向的作用力下呈螺旋线运动，其中，在垂直于磁场方向的电场的作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径，其中，第一灯丝602在低电离能模式下工作；
其中，第一灯丝602在低电离能模式下工作，第二灯丝1002在常规电离能模式下工作。
可以理解的是，其中，第一灯丝602在低电离能模式下工作，如电离能为10-30eV，第二灯丝1002在常规电离能模式下工作，如70eV。如图9所示，在第一灯丝602一侧，装有第一电子推斥极603、径向加速电极(包括电子径向加速正电极和电子径向加速负电极)和电子透镜电极901，而在第二灯丝1002一侧，则仅安装第二电子推斥极1006，而不安装径向加速电极和电子透镜电极。根据应用需要的不同，这两种模式可以来回进行切换。其中，第一电子推斥极603为低电离能电子推斥极，第二电子推斥极1006为常规电离能电子推斥极。
当被测物质的质谱峰之间无重叠干扰现象，或者进入质谱的样品为事先经过分离装置实现了物理上的分离的情况下，采用70eV的常规电离模式进行分析，电子从第二灯丝1002上溢出后，在第二电子推斥极1006和 电离室601的电场作用下，加速向电离室601飞去，穿过电子出射孔702后进入电离室601内部，然后与从样品分子注入孔703进入的分析物分子发生碰撞电离，电离后产生的分子离子和碎片离子在离子推斥极608和离子聚焦透镜组609的共同作用下离开离子源，之后被质量分析器和检测器完成质量分析和检测，通过每一种物质的特征离子就可以实现定性和定量分析。
而当被分析物质的质谱峰之间存在重叠干扰，或者进入质谱的样品没有经过任何的物理上的分离，而是全部一起进入质谱系统的时候，采用低电离能模式。电子从第一灯丝602上溢出后，在第一电子推斥极603和电子透镜电极901的电场作用下加速向电离室601飞去，在飞行过程中，受到径向加速电极和第一电子推斥极603的径向加速电场作用而产生径向速度，然后在磁铁610的磁场中以螺旋线绕电子飞行参考轴604向电离室601运动，穿过电子入射孔701之后进入电离室601内部，然后与从样品分子注入孔703进入的分析物分子发生碰撞电离。通过调节合适的电离能，使得被分析物无碎片离子。电离后产生的分子离子在离子推斥极608和离子聚焦透镜组609的共同作用下离开离子源，之后被质量分析器和检测器完成质量分析和检测。电离后产生的通过分子离子峰就可以实现定性和定量分析。
图9提供的电子轰击电离源装置，可以工作在两种模式下，即灯丝工作在低电离能工作模式和常规电离能工作模式下，可以理解为图9中的电子轰击电离源装置可同时实现图5中的电子轰击电离源装置的功能和图1中常规的电子轰击电离源装置的功能。
电子轰击电离源装置的电离效率与碰撞截面积直接相关，碰撞截面积越大，电离效率越高，碰撞截面积越小，电离效率越低。而碰撞截面积的大小与电子能量相关，随着电子能量的降低，碰撞截面积也降低，因此，当电子轰击电离源装置工作在低电离能模式的时候，其电离效率大幅降低。因此，本申请实施例是充分利用了电子在磁场作用下沿轴做螺旋线运动的原理，其螺旋线的半径与磁场垂直方向(即电子径向速度方向)的电子速度成正比，螺旋线的螺距与电子沿磁场平行方向(即电子的轴向速度方向)的速度成正比。电子能量决定了电子的轴向速度，但是对电子的径向速度 作用有限，本申请实施例在磁场垂直方向增加一个附加电场，使得电子的径向速度得到一个大幅提升，因此，在不改变电子能量的前提下，使得电子的绕轴运动的螺旋线半径增加，而绕轴运动的螺距不变，从而使得电子的整个运动路径得到加长。
作为一个可选的实施例，提供了一种基于电子轰击电离源的电子轰击方法，该方法包括：
第一灯丝通电发热后释放出电子，在第一电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，第一灯丝工作在低电离能模式；
电子通过电离室上对应的电子孔飞入电离室，电子在磁场方向的作用力下呈螺旋线匀速运动，穿过电离室上相应的电子孔之后，被电子接收极接收；
其中，电子在电离室运动的过程中，与注入的被测物质的分子碰撞；在径向加速电极之间形成的垂直于磁场方向的电场作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径。
可以理解的是，本申请实施例为基于图5中的电子轰击电离源装置的电离轰击方法，其中，具体的电子与被测物分子之间的碰撞过程可参见前述的描述，在此不再赘述，主要是通过在磁场垂直方向上施加一电场，垂直于磁场方向的电场作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径。
作为一个可选的实施例，提供了一种基于电子轰击电离源的电子轰击方法，该方法包括：
当打开第一灯丝时，第一灯丝通电发热后释放出电子，在第一电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量；
电子通过电离室上对应的电子孔飞入电离室，电子在磁场方向的作用力下螺旋线匀速运动，最终打在电离室上；
其中，电子在电离室运动的过程中，与注入的被测物质的分子碰撞；在径向加速电极之间形成的垂直于磁场方向的电场作用下，电子运动的螺旋线的半径增大；
或者，
当打开第二灯丝时，第二灯丝通电发热后释放出电子，在第二电子推 斥极和电离室之间所形成的电场作用下，电子获得相应的能量；
电子通过电离室上对应的电子孔飞入电离室，电子在磁场方向的作用力下呈螺旋线匀速运动，最终打在电离室上；
其中，第一灯丝工作于低电离能模式，第二灯丝工作于常规电离能模式。
可以理解的是，本申请实施例为基于图9中的电子轰击电离源装置的电离轰击方法，其中，本申请实施例的电子轰击电离源装置可实现两种工作模式下的电离轰击，每一种工作模式下的电子与被测物分子之间的碰撞过程可参见前述的描述，在此不再赘述。
作为一个可选的实施例，提供了一种基于电子轰击电离源装置的物质分析方法，包括：
打开第一灯丝，第一灯丝通电发热后释放出电子，在第一电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，第一灯丝工作在软电离模式；
电子通过电离室上对应的电子孔飞入电离室，与注入的被测物质的分子发生碰撞电离，由此软电离得到被测物质的分子量信息；
关闭第一灯丝，打开第二灯丝，第二灯丝通电发热后释放出电子，在第二电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，所述第二灯丝工作在硬电离模式；
电子通过电离室上对应的电子孔飞入电离室，与注入的被测物质的分子发生碰撞电离，由此硬电离得到被测物质的碎片离子信息；
根据被测物质的分子量信息和碎片离子信息，计算出被测物质的分子结构。
可以理解的是，本申请实施例中，一个灯丝工作在软电离模式，另一个灯丝工作在硬电离模式(70eV)。先打开第一灯丝，第一灯丝通电发热后释放出电子，电子通过电离室上对应的电子孔飞入电离室，与注入的被测物质的分子碰撞，得到软电离后的分子量信息。根据分子量信息只能得到该被测物质是哪种物质分子，但有可能有同分异构体存在，分子量相同，但是分子结构不同，其碎片会有不同，比如碎片离子的丰度不一样。
在这种情况下，关闭第一灯丝，打开第二灯丝，第二灯丝工作在硬电 离模式，第二灯丝通电发热后释放出电子，电子通过电离室上对应的电子孔飞入电离室，与被测物质的分子进行碰撞，得到被测物质的碎片离子信息。
根据被测物质的分子量和碎片离子信息，可计算出这些碎片都来自于哪一种结构的物质，也就是说，通过两个灯丝分别工作于软电离模式和硬电离模式，可以对同分异构体进行区分，从而避免软电离模式无法区分同分异构体的问题。
其中，被测物质可以为单一物质，也可以为多种不同的混合物质，在这里，单一物质是指物质的分子量信息相同，结构也相同；如果两种物质的分子量相同，而分子结构不同，那么这两种物质就是两种不同的物质。由于物质间存在同分异构体的现象，因此，仅仅根据物质的分子量信息，是无法确定被测物质的分子结构的。故本申请实施例先采用第一灯丝对被测物质进行软电离，得到被测物质的分子量信息；然后采用第二灯丝对被测物质进行硬电离，得到被测物质的碎片离子信息。根据被测物质的分子量信息和碎片离子信息，可分析得到被测物质的分子结构。无论被测物质是单一物质还是多种混合物质，均可以采用本申请实施例的软电离和硬电离的方式，分析得到每一种物质的分子结构。
本申请实施例提供的一种电子轰击电离源装置、电离轰击方法及物质分析方法，所采用的径向加速电场，将使得电子绕轴螺旋线的半径增加，从而在不改变电子能量的前提下，使得电子的运动路径加长，因此碰撞截面积增加，从而使得电离效率得到提高。采用本申请实施例提供的电子轰击电离源装置进行电离轰击，将使得电子轰击电离源装置在低电离能模式下也能获得与传统电子轰击电离源装置同等的电离效率，从而使得电离能降低后灵敏度仍然不降低。因此，低电离能工作模式下的电子轰击电离源装置就可以直接用于对复杂样品的直接分析，而不用依靠色谱等分离手段，仪器的体积和功耗都会变得更小。
此外，在电子接收极上，施加与电子推斥极相同的电压，当电子穿过电离室飞向电子推斥极时，由于受到电场的反向作用力，电子将被反弹回电离室，从而使得电子的运动路线长度得到进一步的提高，从而提高电离效率；
使用两个灯丝分别工作在软电离模式和硬电离模式，得到被测物质的分子量信息和碎片离子信息，可以区分同分异构体，从而实现更准确的定性分析。
最后应说明的是：以上实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的精神和范围。

Claims (10)

  1. 一种电子轰击电离源装置，包括电离室、第一灯丝、第一电子推斥极、电子接收极、离子推斥极、离子聚焦透镜组和磁铁，其特征在于，
    所述第一电子推斥极靠近电离室的内侧、第一灯丝的上下或者前后，放置径向加速电极，在径向加速电极之间形成垂直于磁场方向的电场；
    通电发热后的第一灯丝溢出的电子在磁场方向的作用力下呈螺旋线运动，其中，在垂直于磁场方向的电场的作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径，其中，第一灯丝在低电离能模式下工作。
  2. 根据权利要求1所述的电子轰击电离源装置，其特征在于，所述径向加速电极包括对称位于所述第一灯丝上下或前后的电子径向加速正电极和电子径向加速负电极，所述第一电子推斥极和所述电子径向加速负电极为一体，且呈L型。
  3. 根据权利要求1所述的电子轰击电离源装置，其特征在于，所述电子接收极的电压值与所述第一电子推斥极的电压值相同，使得所述电子在所述电子接收极和所述第一电子推斥极之间来回反弹，进而增加电子的实际运动路径。
  4. 根据权利要求1-3所述的电子轰击电离源装置，其特征在于，在所述径向加速电极和所述电离室之间放置电子透镜电极，所述电子透镜电极中间位置开设有电子透过孔，所述电子透过孔的中心位于电子飞行参考轴上。
  5. 一种电子轰击电离源装置，包括电离室、第一灯丝、第一电子推斥极、第二电子推斥极、离子推斥极、离子聚焦透镜组和磁铁，其特征在于，在所述第二电子推斥极和所述电离室之间安装第二灯丝，其中，所述第二灯丝和所述第一灯丝分别对称位于所述电离室的两侧；
    在所述第一电子推斥极靠近电离室的内侧、在第一灯丝的上下或者前后，放置径向加速电极，在径向加速电极之间形成垂直于磁场方向的电场；
    当打开第一灯丝时，通电发热后的第一灯丝溢出的电子在磁场方向的作用力下呈螺旋线运动，其中，在垂直于磁场方向的电场的作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径；
    其中，第一灯丝在低电离能模式下工作，第二灯丝在常规电离能模式下工作。
  6. 根据权利要求5所述的电子轰击电离源装置，其特征在于，所述第二电子推斥极的电压值与所述第一电子推斥极的电压值相同，使得所述电子在所述第二电子推斥极和所述第一电子推斥极之间来回反弹，进而增加电子的实际运动路径。
  7. 根据权利要求5-6所述的电子轰击电离源装置，其特征在于，在所述径向加速电极和所述电离室之间放置电子透镜电极，所述电子透镜电极中间位置开设有电子透过孔，所述电子透过孔的中心位于电子飞行参考轴上。
  8. 一种基于权利要求1所述的电子轰击电离源装置的电离轰击方法，其特征在于，包括：
    第一灯丝通电发热后释放出电子，在第一电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，所述第一灯丝工作在低电离能模式；
    电子通过电离室上对应的电子孔飞入电离室，电子在磁场方向的作用力下呈螺旋线匀速运动，穿过电离室上相应的电子孔之后，被电子接收极接收；
    其中，电子在电离室运动的过程中，与注入的被测物质的分子碰撞；在径向加速电极之间形成的垂直于磁场方向的电场作用下，电子运动的螺旋线的半径增大，进而增加电子的实际运动路径。
  9. 一种基于权利要求5所述的电子轰击电离源装置的电离轰击方法，其特征在于，包括：
    当打开第一灯丝时，第一灯丝通电发热后释放出电子，在第一电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量；
    电子通过电离室上对应的电子孔飞入电离室，电子在磁场方向的作用力下螺旋线匀速运动，最终打在电离室上；
    其中，电子在电离室运动的过程中，与注入的被测物质的分子发生碰撞电离；在径向加速电极之间形成的垂直于磁场方向的电场作用下，电子运动的螺旋线的半径增大；
    或者，
    当打开第二灯丝时，第二灯丝通电发热后释放出电子，在第二电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量；
    电子通过电离室上对应的电子孔飞入电离室，电子在磁场方向的作用力下呈螺旋线匀速运动，最终打在电离室上；
    其中，第一灯丝在低电离能模式下工作，第二灯丝在常规电离能模式下工作。
  10. 一种基于权利要求5所述的电子轰击电离源装置的物质分析方法，其特征在于，包括：
    打开第一灯丝，第一灯丝通电发热后释放出电子，在第一电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，所述第一灯丝工作在软电离模式；
    电子通过电离室上对应的电子孔飞入电离室，与注入的被测物质的分子发生碰撞电离，由此软电离得到被测物质的分子量信息；
    关闭第一灯丝，打开第二灯丝，第二灯丝通电发热后释放出电子，在第二电子推斥极和电离室之间所形成的电场作用下，电子获得相应的能量，所述第二灯丝工作在硬电离模式；
    电子通过电离室上对应的电子孔飞入电离室，与注入的被测物质的分子发生碰撞电离，由此硬电离得到被测物质的碎片离子信息；
    根据被测物质的分子量和碎片离子信息，计算出被测物质的分子结构。
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