A multi-mode photoionization source

Abstract

The present invention belongs to the technical field of mass spectrometry ionization source, and specifically relates to a multi-mode photoionization source, including a vacuum ultraviolet light source and an ion repeller electrode, a first and a second grid electrode, an ion transmission electrode and an ion extraction electrode arranged in sequence from left to right along the axis direction of the first injection port; a photoelectron generating electrode piece is arranged between the ion repeller electrode and the ion transmission electrode; the first and the second grid electrodes are planar metal meshes, parallel to the ion repeller electrode, and vertically connected to the photoelectron generating electrode piece through an insulating fixed column; a second injection port is arranged between the photoelectron generating electrode piece and the ion transmission electrode, which is perpendicular to the first injection port; the vacuum ultraviolet light is perpendicular to the direction of ion movement, so that the photoionization mode is single and the mass spectrum is easy to analyze. By adjusting the switches of the first and the second injection ports, the air pressure between the ion repeller electrode and the ion extraction electrode, and the voltage difference between the first and the second grid electrodes, the switching of the three ionization modes of photoionization, photoelectron ionization and chemical ionization is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of mass spectrometry ionization sources, and in particular relates to a multi-mode photoionization source. Background Art

[0002] Vacuum ultraviolet photoionization is a threshold ionization technique, and the ionization process can be achieved by making the photon energy equal to or higher than the ionization energy of the molecule to be measured. Vacuum ultraviolet photoionization is a soft ionization technique that mainly produces molecular ions, with simple spectra and easy to interpret.

[0003] The composite ionization source of vacuum ultraviolet photoionization and chemical ionization for mass spectrometry invented by Li Haiyang, Hua Lei, etc. (application number CN201010567193.0) can realize the switching of vacuum ultraviolet photoionization and chemical ionization modes under certain ionization source pressure conditions. However, in the photoionization mode, the vacuum ultraviolet light is parallel to the direction of ion movement, and the vacuum ultraviolet light directly shines on the ion extraction electrode to generate a large number of photoelectrons. The photoelectrons gain energy in the electric field. The sample molecules are likely to be photoionized by photoelectrons at the same time to produce fragments, resulting in a non-single photoionization mode, thereby increasing the difficulty of mass spectrum analysis in the photoionization mode and narrowing the linear range. Summary of the invention

[0004] The present invention proposes a multi-mode photoionization source, in which vacuum ultraviolet light is perpendicular to the direction of ion movement, so that the photoionization mode is single and the mass spectrum is easy to analyze. In addition, a photoelectron ionization mode is added, and the switching of the three ionization modes of photoionization, photoelectron ionization and chemical ionization can be realized by adjusting the switch of the first injection port and the second injection port, the gas pressure between the ion repeller electrode and the ion extraction electrode, and the voltage difference between the first grid electrode and the second grid electrode.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A multi-mode photoionization source comprises a vacuum ultraviolet light source and an ion repeller electrode, a first grid electrode, a second grid electrode, an ion transport electrode and an ion extraction electrode which are sequentially arranged from left to right along the axis direction of a first injection port;

[0007] The ion repeller electrode, ion transport electrode and ion extraction electrode are all plate structures with central through holes, and are placed in parallel, spaced apart, and coaxially with the central through holes, on the same axis as the center of the first injection port, and perpendicular to the direction in which the vacuum ultraviolet light is emitted by the vacuum ultraviolet light source;

[0008] A photoelectron generating electrode is arranged between the ion repeller electrode and the ion transport electrode; the photoelectron generating electrode is a planar plate structure; the first grid electrode and the second grid electrode are planar metal mesh electrodes, which are parallel to the ion repeller electrode and vertically connected to the photoelectron generating electrode through an insulating fixing column;

[0009] A second injection port is provided between the ion transport electrodes of the photoelectron generating electrode, and the second injection port is perpendicular to the first injection port;

[0010] The ion repeller electrode, the first grid electrode, the second grid electrode, the ion transport electrode and the ion extraction electrode are sequentially loaded with different voltages in the order of the absolute value of the voltage from high to low, so as to form an ion extraction electric field of 0-500V / cm in the axial direction;

[0011] Under the action of the photoelectric effect, the vacuum ultraviolet light emitted by the vacuum ultraviolet light source irradiates the photoelectron generating electrode, and photoelectrons escape. By adjusting the switch of the first injection port and the second injection port, the air pressure between the ion repeller electrode and the ion extraction electrode, and the voltage difference between the first grid electrode and the second grid electrode, the switching of the three ionization modes of photoionization, photoelectron ionization, and chemical ionization is realized.

[0012] In the photoionization mode, the first injection port is open and the second injection port is closed; the gas pressure in the ionization zone between the ion repeller electrode and the ion extraction electrode is maintained at 10 -3 Pa~10 3 Pa; the voltage difference between the first grid electrode and the second grid electrode is 0-5V; the sample enters from the first injection port and is directly ionized by vacuum ultraviolet light;

[0013] In the photoelectron ionization mode, the first injection port is open and the second injection port is closed; the gas pressure in the ionization zone between the ion repeller electrode and the ion extraction electrode is maintained at 10 -3 Pa~10 1 Pa; the voltage difference between the first grid electrode and the second grid electrode is 10-100V; the vacuum ultraviolet light emitted by the vacuum ultraviolet light source irradiates the photoelectron generating electrode, and under the action of the photoelectric effect, the photoelectron generating electrode escapes the photoelectron, and the photoelectron obtains 10-100eV energy between the first grid electrode and the second grid electrode; the sample enters from the first injection port and is ionized by the photoelectron;

[0014] In the chemical ionization mode, the first injection port and the second injection port are opened at the same time; the gas pressure in the ionization zone between the ion repeller electrode and the ion extraction electrode is maintained at 10 1 Pa~10 3Pa; the voltage difference between the first grid electrode and the second grid electrode is 0-500V; the reagent molecules enter from the first injection port and are ionized into reagent ions by vacuum ultraviolet light or photoelectrons, and the reagent ions then ionize the sample entering from the second injection port.

[0015] The ion transport electrode is a plate-type structure in which one or more electrodes are spaced apart from each other, coaxially and parallelly arranged; when there are more than one ion transport electrode, different voltages are loaded on the multiple ion transport electrodes in sequence from left to right according to the absolute value of the voltage from high to low.

[0016] The diameter of the central through hole of the ion transmission electrode is 1-20 mm; the diameter of the central through hole of the ion extraction electrode is 0.1-5 mm; and the distance between the ion repeller electrode and the ion extraction electrode is 10-250 mm.

[0017] The vacuum ultraviolet light source is a gas discharge lamp, an ultraviolet light emitting diode, a synchrotron radiation light source or a laser light source.

[0018] Beneficial Effects

[0019] The present invention proposes a multi-mode photoionization source, in which vacuum ultraviolet light is perpendicular to the direction of ion movement, so that the photoionization mode is single and the mass spectrum is easy to analyze. In addition, a photoelectron ionization mode is added, and the switching of the three ionization modes of photoionization, photoelectron ionization and chemical ionization can be realized by adjusting the switch of the first injection port and the second injection port, the gas pressure between the ion repeller electrode and the ion extraction electrode, and the voltage difference between the first grid electrode and the second grid electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings further illustrate the present invention, but the contents in the accompanying drawings do not constitute any limitation to the present invention.

[0021] Figure 1 It is a multi-mode photoionization source of the present invention.

[0022] In the figure, 1. vacuum ultraviolet light source; 2. first injection port; 3. ion repeller electrode; 4. photoelectron generating electrode; 5. vacuum ultraviolet light; 6. first grid electrode; 7. second grid electrode; 8. insulating fixing column; 9. second injection port; 10. ion transport electrode; 11. ion extraction electrode. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0026] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0027] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0028] Example 1

[0029] like Figure 1As shown, a multi-mode photoionization source of the present invention includes a multi-mode photoionization source, characterized in that it includes a vacuum ultraviolet light source 1 and an ion repeller electrode 3, a first grid electrode 6, a second grid electrode 7, an ion transport electrode 10 and an ion extraction electrode 11 arranged in sequence from left to right along the axis direction of the first injection port 2;

[0030] The ion repeller electrode 3, the ion transport electrode 10 and the ion extraction electrode 11 are all plate structures with a central through hole, and are placed in parallel, spaced apart, and coaxially with the central through hole, on the same axis as the center of the first injection port 2, and perpendicular to the direction in which the vacuum ultraviolet light 5 is emitted from the vacuum ultraviolet light source 1;

[0031] A photoelectron generating electrode piece 4 is disposed between the ion repeller electrode 3 and the ion transport electrode 10; the photoelectron generating electrode piece 4 is a planar plate structure; the first grid electrode 6 and the second grid electrode 7 are planar metal mesh electrodes, which are parallel to the ion repeller electrode 3 and vertically connected to the photoelectron generating electrode piece 4 through an insulating fixing column 8;

[0032] A second injection port 9 is provided between the ion transmission electrodes 10 of the photoelectron generating electrode piece 4, and the second injection port 9 is perpendicular to the first injection port 2;

[0033] The ion repeller electrode 3, the first grid electrode 6, the second grid electrode 7, the ion transport electrode 10 and the ion extraction electrode 11 are sequentially loaded with different voltages in the order of the absolute value of the voltage from high to low, so as to form an ion extraction electric field of 0-500V / cm in the axial direction;

[0034] Under the action of the photoelectric effect, the vacuum ultraviolet light 5 emitted by the vacuum ultraviolet light source 1 irradiates the photoelectron generating electrode 4, and photoelectrons escape. By adjusting the voltage difference between the first grid electrode 6 and the second grid electrode 7, the air pressure between the ion repeller electrode 3 and the ion extraction electrode 11, and the switch of the first injection port 2 and the second injection port 9, the switching of the three ionization modes of photoionization, photoelectron ionization and chemical ionization is realized.

[0035] As one of the embodiments, the ion transport electrode 10 is a plate structure of three mutually spaced, coaxial and parallel plates, and different voltages are loaded in sequence from left to right in the order of the absolute value of the voltage from high to low.

[0036] In the photoionization mode, the first injection port 2 is opened and the second injection port 9 is closed. As one of the embodiments, the gas pressure in the ionization zone between the ion repeller electrode 3 and the ion extraction electrode 11 is 50 Pa; the voltage difference between the first grid electrode 6 and the second grid electrode 7 is 2V. The voltage of the ion repeller electrode 3 is 22V; the voltage of the first grid electrode 6 is 18V, and the voltage of the second grid electrode 7 is 16V; the voltages of the ion transmission electrode 10 are 12, 10, and 8V respectively; and the voltage of the ion extraction electrode 11 is 5V. The sample benzene enters from the first injection port 2 and is directly ionized by the vacuum ultraviolet light 5.

[0037] In the photoelectron ionization mode, the first injection port 2 is opened and the second injection port 9 is closed. As one of the embodiments, the gas pressure in the ionization zone between the ion repeller electrode 3 and the ion extraction electrode 11 is 1Pa; the voltage difference between the first grid electrode 6 and the second grid electrode 7 is 70V. As one of the embodiments, the voltage of the ion repeller electrode 3 is 90V; the voltage of the first grid electrode 6 is 86V, and the voltage of the second grid electrode 7 is 16V; the voltages of the ion transmission electrode 10 are 12, 10, and 8V respectively; and the voltage of the ion extraction electrode 11 is 5V. The vacuum ultraviolet light 5 emitted by the vacuum ultraviolet light source 1 irradiates the photoelectron generating electrode 4. Under the action of the photoelectric effect, the photoelectron generating electrode 4 escapes photoelectrons, and the photoelectrons obtain 70eV energy between the first grid electrode 6 and the second grid electrode 7. The sample sulfur hexafluoride enters from the first injection port 2 and is ionized by photoelectrons.

[0038] In the chemical ionization mode, the first injection port 2 and the second injection port 9 are opened simultaneously;

[0039] As one of the embodiments, the gas pressure in the ionization zone between the ion repeller electrode 3 and the ion extraction electrode 11 is 200 Pa; the voltage difference between the first grid electrode 6 and the second grid electrode 7 is 5V. The voltage of the ion repeller electrode 3 is 25V; the voltage of the first grid electrode 6 is 21V, and the voltage of the second grid electrode 7 is 16V; the voltages of the ion transport electrode 10 are 12, 10, and 8V respectively; and the voltage of the ion extraction electrode 11 is 5V. The reagent molecule nitric oxide enters from the first injection port 2, and is ionized by the vacuum ultraviolet light 5 into nitric oxide reagent ions, which then ionize the sample formaldehyde entering from the second injection port 9;

[0040] As one of the embodiments, the gas pressure in the ionization zone between the ion repeller electrode 3 and the ion extraction electrode 11 is 200 Pa; the voltage difference between the first grid electrode 6 and the second grid electrode 7 is 100V. The voltage of the ion repeller electrode 3 is 120V; the voltage of the first grid electrode 6 is 116V, and the voltage of the second grid electrode 7 is 16V; the voltages of the ion transmission electrode 10 are 12, 10, and 8V respectively; and the voltage of the ion extraction electrode 11 is 5V. The vacuum ultraviolet light 5 emitted by the vacuum ultraviolet light source 1 irradiates the photoelectron generating electrode piece 4. Under the action of the photoelectric effect, the photoelectron generating electrode piece 4 escapes photoelectrons, and the photoelectrons obtain 100eV energy between the first grid electrode 6 and the second grid electrode 7. The reagent molecule oxygen enters from the first injection port 2 and is ionized into oxygen reagent ions by the photoelectrons. The oxygen reagent ions then ionize the sample pentane entering from the second injection port 9.

[0041] Preferably, the diameter of the central through hole of the ion transport electrode 10 is 10 mm; the diameter of the central through hole of the ion extraction electrode 11 is 1 mm; and the distance between the ion repeller electrode 3 and the ion extraction electrode 11 is 50 mm.

[0042] The vacuum ultraviolet light source 1 is a gas discharge lamp, an ultraviolet light emitting diode, a synchrotron radiation light source or a laser light source.

[0043] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific embodiments of the present invention without creative work, and these equivalent variations or substitutions are all included in the scope defined by the claims of this application.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-mode photoionization source, characterized in that: It comprises a vacuum ultraviolet light source (1) and an ion repeller electrode (3), a first grid electrode (6), a second grid electrode (7), an ion transport electrode (10) and an ion extraction electrode (11) which are arranged in sequence from left to right along the axis direction of the first injection port (2); The ion repeller electrode (3), the ion transport electrode (10) and the ion extraction electrode (11) are all plate-type structures with a central through hole, and are arranged in parallel, spaced apart, and coaxially with the central through hole, on the same axis as the center of the first injection port (2), and perpendicular to the direction in which the vacuum ultraviolet light (5) is emitted by the vacuum ultraviolet light source (1); A photoelectron generating electrode (4) is provided between the ion repeller electrode (3) and the ion transport electrode (10); the photoelectron generating electrode (4) is a planar plate structure; the first grid electrode (6) and the second grid electrode (7) are planar metal mesh electrodes, which are parallel to the ion repeller electrode (3) and vertically connected to the photoelectron generating electrode (4) via an insulating fixing column (8); A second injection port (9) is provided between the photoelectron generating electrode (4) and the ion transport electrode (10), and the second injection port (9) is perpendicular to the first injection port (2); The ion repeller electrode (3), the first grid electrode (6), the second grid electrode (7), the ion transport electrode (10) and the ion extraction electrode (11) are sequentially loaded with different voltages in the order of absolute voltage values ​​from high to low, so as to form an ion extraction electric field in the axial direction; By adjusting the switches of the first injection port (2) and the second injection port (9), the gas pressure between the ion repeller electrode (3) and the ion extraction electrode (11), and the voltage difference between the first grid electrode (6) and the second grid electrode (7), switching among the three ionization modes of photoionization, photoelectron ionization and chemical ionization is achieved.

2. A multi-mode photoionization source according to claim 1, characterized in that: In the photoionization mode, the first injection port (2) is opened and the second injection port (9) is closed; the gas pressure in the ionization zone between the ion repeller electrode (3) and the ion extraction electrode (11) is maintained at 10 -3 Pa~10 3 Pa; the voltage difference between the first grid electrode (6) and the second grid electrode (7) is 0-5V; the sample enters from the first injection port (2) and is directly ionized by the vacuum ultraviolet light (5); In the photoelectron ionization mode, the first injection port (2) is opened and the second injection port (9) is closed; the gas pressure in the ionization zone between the ion repeller electrode (3) and the ion extraction electrode (11) is maintained at 10 -3 Pa~10 1 Pa; the voltage difference between the first grid electrode (6) and the second grid electrode (7) is 10-100 V; the sample enters from the first injection port (2) and is ionized by photoelectrons; In the chemical ionization mode, the first injection port (2) and the second injection port (9) are opened simultaneously; the gas pressure in the ionization zone between the ion repeller electrode (3) and the ion extraction electrode (11) is maintained at 10 1 Pa~10 3 Pa; the voltage difference between the first grid electrode (6) and the second grid electrode (7) is 0-500V; the reagent molecules enter from the first injection port (2), are ionized into reagent ions by vacuum ultraviolet light (5) or photoelectrons, and the reagent ions then ionize the sample entering from the second injection port (9).

3. A multi-mode photoionization source according to claim 1, characterized in that: The ion transport electrode (10) is a plate-type structure in which one or more ion transport electrodes are spaced apart from each other, coaxially and in parallel. When there are more than one ion transport electrode (10), different voltages are sequentially loaded on the multiple ion transport electrodes from left to right in the order of the absolute value of the voltage from high to low.

4. A multi-mode photoionization source according to claim 1, characterized in that: The diameter of the central through hole of the ion transmission electrode (10) is 1 to 20 mm; the diameter of the central through hole of the ion extraction electrode (11) is 0.1 to 5 mm; and the distance between the ion repelling electrode (3) and the ion extraction electrode (11) is 10 to 250 mm.

5. A multi-mode photoionization source according to claim 1, characterized in that: The vacuum ultraviolet light source (1) is a gas discharge lamp, an ultraviolet light emitting diode, a synchrotron radiation light source or a laser light source.

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