Laser-induced ultrasonic desorption photoelectron ionization source for mass spectrum

Abstract

The invention relates to the technical field of mass spectrum ionization sources, in particular to a laser-induced ultrasonic desorption photoelectron ionization source for mass spectrum. Comprising a laser-induced ultrasonic desorption source, and a sample to be detected, an ion repulsion electrode, a plurality of groups of ionization chamber electrodes, an ion extraction electrode, an ion focusing electrode and an ion emission electrode which are sequentially arranged on one side of the laser-induced ultrasonic desorption source, and the vacuum ultraviolet light equipment is arranged among the plurality of groups of ionization chamber electrodes. The laser-induced ultrasonic desorption photoelectron ionization source for the mass spectrum has the advantages of being low in detection limit, wide in sample selection range, long in service life and low in power consumption. According to the invention, not only can photoelectrons be inhibited, but also the photoelectrons can be enhanced, and switching between an ultraviolet light ionization mode and a photoelectron ionization mode and regulation and control of photoelectron energy can be realized by adjusting the voltage difference between the electron escape electrode and the ionization chamber electrode.

Description

Technical Field

[0001] The invention relates to the technical field of mass spectrometry ionization sources, in particular to a laser-induced ultrasonic desorption photoelectron ionization source for mass spectrometry. Background Art

[0002] Laser-induced acoustic desorption (LIAD) is a "soft desorption" technology that can desorb analytes deposited on a substrate into the gas phase for mass spectrometry analysis and detection. Specifically, LIAD is a technology that generates high-energy sound waves by irradiating a beam of high-energy laser on the back of a metal foil. The sound waves transfer energy to the analytes deposited on the front of the substrate through the substrate, thereby desorbing the analytes into the gas phase. Since the high-energy laser does not directly contact the sample to be tested, LIAD is a mild "soft desorption" technical means, and the sample is desorbed into the gas phase in a neutral form. Therefore, when using LIAD in combination with a mass spectrometer for analysis and detection, an additional ionization source is essential. For example, by combining with an electron impact (EI) ionization source and a vacuum ultraviolet (VUV) ionization source for sample analysis and detection. However, LIAD combined with an electron impact ionization source has high power consumption, short life, and weak molecular ion peaks, making it difficult to identify complex samples; LIAD combined with a vacuum ultraviolet photoionization source lacks characteristic fragment molecules and the ionization energy of the sample to be tested cannot be higher than the photon energy. LIAD requires an effective ionization source.

[0003] Therefore, it is necessary to provide a laser-induced ultrasonic desorption photoelectron ionization source for mass spectrometry with low detection limit, wide sample selection range, long life and low power consumption. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry with low detection limit, wide sample selection range, long life and low power consumption.

[0005] To achieve the above-mentioned object and other related objects, the present invention provides a laser-induced ultrasonic desorption photoelectron ionization source for mass spectrometry, comprising:

[0006] Laser-induced ultrasonic desorption source;

[0007] A sample to be tested, an ion repeller electrode, multiple groups of ion chamber electrodes, an ion extraction electrode, an ion focusing electrode and an ion emission electrode are sequentially arranged on one side of the laser induced ultrasonic desorption source;

[0008] The vacuum ultraviolet light device is arranged between the multiple groups of ionization chamber electrodes.

[0009] In one embodiment of the present invention, the laser induced ultrasonic desorption source comprises:

[0010] A focusing lens is disposed at one end of the laser-induced ultrasonic desorption photoelectron ionization source;

[0011] A substrate, which is spaced apart from the focusing lens, and a sample molecule is arranged on a side of the substrate close to the focusing lens, and a sample to be detected is arranged on a side of the substrate away from the focusing lens;

[0012] The laser light, after being focused by the focusing lens, is irradiated onto one side of the substrate on which the sample molecules are deposited.

[0013] In one embodiment of the present invention, the vacuum ultraviolet light device comprises:

[0014] A true ultraviolet light source for emitting vacuum ultraviolet light;

[0015] The electron escape electrode is arranged at the bottom of the true light ultraviolet light source, and the vacuum ultraviolet light irradiates the electron escape electrode.

[0016] In one embodiment of the present invention, the vacuum ultraviolet light device further comprises:

[0017] Two insulating fixing members are installed on both sides of the electron escape electrode.

[0018] In one embodiment of the present invention, the ionization chamber electrode is disposed on the electron escape electrode, and the electron escape electrode and the center of the true light ultraviolet light source are on the same axis and perpendicular to the axis direction of the true light ultraviolet light source.

[0019] In one embodiment of the present invention, two groups of ionization chamber electrodes are provided, and the two groups of ionization chamber electrodes are distributed on both sides of the vacuum ultraviolet light, and one ionization chamber electrode in each group is fixed on the insulating fixing member.

[0020] In one embodiment of the present invention, the electron escape electrode is an integrated cylindrical shape.

[0021] In one embodiment of the present invention, the ion repeller electrode, ion extraction electrode, ion focusing electrode and ion exit electrode are all arranged in a group, and the ion repeller electrode, ion chamber electrode, ion extraction electrode, ion focusing electrode and ion exit electrode are all loaded with different voltages, and the ion extraction electrode and ion exit electrode constitute a group of electrostatic lenses to eliminate the spherical aberration of the ion beam to form a parallel ion beam.

[0022] In one embodiment of the present invention, the ion repeller electrode, multiple groups of ion chamber electrodes, ion extraction electrode, ion focusing electrode and ion output electrode are all central through hole structures, and are parallel to each other, spaced apart, and coaxially arranged with central through holes.

[0023] In one embodiment of the present invention, the ion repeller electrode, multiple groups of ionization chamber electrodes, ion extraction electrode, ion focusing electrode and ion exit electrode are on the same axis as the center of the laser and perpendicular to the direction in which the true light ultraviolet light source emits vacuum ultraviolet light.

[0024] As described above, the laser-induced ultrasonic desorption photoelectron ionization source for mass spectrometry of the present invention has the following beneficial effects:

[0025] (1) The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry of the present invention comprises a laser induced ultrasonic desorption source, a sample to be measured, an ion repeller electrode, multiple groups of ionization chamber electrodes, an ion extraction electrode, an ion focusing electrode and an ion emission electrode, and a vacuum ultraviolet light device, and has the characteristics of low detection limit, wide sample selection range, long life and low power consumption.

[0026] (2) The laser-induced ultrasonic desorption photoelectron ionization source for mass spectrometry of the present invention can not only suppress photoelectrons, but also enhance photoelectrons. By adjusting the voltage difference between the electron escape electrode and the ionization chamber electrode, the switching between the ultraviolet photoionization mode and the photoelectron ionization mode and the regulation of the photoelectron energy can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural diagram of a laser-induced ultrasonic desorption photoelectron ionization source for mass spectrometry provided in an embodiment of the present application.

[0028] Component number description

[0029] 1 True light UV light source

[0030] 2 Laser

[0031] 3 Focusing lens

[0032] 4 Base

[0033] 5 Samples to be tested

[0034] 6 Ion repeller electrode

[0035] 7 Ionization chamber electrodes

[0036] 8 Insulation fixings

[0037] 9 Vacuum ultraviolet light

[0038] 10 Electron Emission Electrode

[0039] 11. Ion extraction electrode

[0040] 12 Ion Focusing Electrode

[0041] 13. Ion emission electrode DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0043] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0044] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] It should be noted that the illustrations provided in the following embodiments are only used to illustrate the basic concept of the present invention in a schematic manner, and thus the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0046] The photoelectron ionization source combines the above two ionization sources. Specifically, under the action of the photoelectric effect, photoelectrons will escape when light is irradiated on the metal surface. The electrons gain energy in the electric field and photoelectron ionization can occur. The vacuum ultraviolet light emitted by the vacuum ultraviolet lamp can also directly photoionize the sample molecules to form sample ions.

[0047] See also Figure 1 , Figure 1The present invention provides a laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry, comprising a laser induced ultrasonic desorption source; a sample to be tested 5, an ion repeller electrode 6, a plurality of ionization chamber electrodes 7, an ion extraction electrode 11, an ion focusing electrode 12 and an ion emission electrode 13 arranged in sequence on one side of the laser induced ultrasonic desorption source; and a vacuum ultraviolet light device arranged between the plurality of ionization chamber electrodes 7.

[0048] Specifically, the laser induced ultrasonic desorption source includes a focusing lens 3, a substrate 4, and a laser 2. The focusing lens 3 is arranged at one end of the laser induced ultrasonic desorption photoelectron ionization source; the substrate 4 is spaced apart from the focusing lens 3, and sample molecules are arranged on the side of the substrate 4 close to the focusing lens 3, and the sample 5 to be detected is arranged on the side of the substrate 4 away from the focusing lens 3; after being focused by the focusing lens 3, the laser 2 is irradiated on the side of the substrate 4 where the sample molecules are deposited.

[0049] Specifically, the vacuum ultraviolet light device includes a true light ultraviolet light source 1 and an electron escape electrode 10 . The true light ultraviolet light source 1 is used to emit vacuum ultraviolet light 9 . The electron escape electrode 10 is arranged at the bottom of the true light ultraviolet light source 1 , and the vacuum ultraviolet light 9 is irradiated on the electron escape electrode 10 .

[0050] Specifically, the vacuum ultraviolet light device further includes two insulating fixing members 8 , which are installed on both sides of the electron escape electrode 10 .

[0051] Specifically, the ionization chamber electrode 7 is disposed on the electron escape electrode 10 , and the electron escape electrode 10 is coaxial with the center of the true light ultraviolet light source 1 and is perpendicular to the axial direction of the true light ultraviolet light source 1 .

[0052] Specifically, two groups of ionization chamber electrodes 7 are provided, and the two groups of ionization chamber electrodes 7 are distributed on both sides of the vacuum ultraviolet light 9, and one ionization chamber electrode 7 in each group is fixed on the insulating fixing member 8. The electron escape electrode 10 is an integrated cylindrical shape.

[0053] Specifically, the ion repeller electrode 6, the ion extraction electrode 11, the ion focusing electrode 12 and the ion exit electrode 13 are all arranged in a group, and the ion repeller electrode 6, the ion chamber electrode 7, the ion extraction electrode 11, the ion focusing electrode 12 and the ion exit electrode 13 are all loaded with different voltages, and the ion extraction electrode 11 and the ion exit electrode 13 constitute a group of electrostatic lenses to eliminate the spherical aberration of the ion beam to form a parallel ion beam.

[0054] Specifically, the ion repeller electrode 6, the multiple groups of ion chamber electrodes 7, the ion extraction electrode 11, the ion focusing electrode 12 and the ion emission electrode 13 are all central through-hole structures, and are parallel to each other, spaced apart, and coaxially arranged with the central through-holes.

[0055] Specifically, the ion repeller electrode 6 , multiple groups of ion chamber electrodes 7 , ion extraction electrode 11 , ion focusing electrode 12 and ion emission electrode 13 are on the same axis as the center of the laser 2 and are perpendicular to the direction in which the true light ultraviolet light source 1 emits the vacuum ultraviolet light 9 .

[0056] Under the action of the photoelectric effect, when the vacuum ultraviolet light emitted by the true ultraviolet light source 1 irradiates the electron escape electrode 10, photoelectrons will escape. By adjusting the voltage difference between the electron escape electrode 10 and the ionization chamber electrode 7, the photoelectrons can be suppressed or enhanced, and the switching between the ultraviolet photoionization mode and the photoelectron ionization mode and the regulation of the photoelectron energy can be achieved.

[0057] In the photoelectron ionization mode, the ionization source has the advantages of both ultraviolet photoionization and electron impact ionization. This ionization source can enhance the signal peak of molecular ions based on the fragments produced by electron impact ionization, and its life span and power consumption are better than those of electron impact ionization sources.

[0058] When the voltage of the electron escape electrode 10 is higher than the voltage of the ionization chamber electrode 7, the photoelectrons move toward the electron escape electrode 10, collide with the electron escape electrode 10 and are annihilated, and the energy of the photoelectrons is zero.

[0059] When the voltage of the electron escape electrode 10 is lower than the voltage of the ionization chamber electrode 7, the photoelectrons move toward the center of the ionization chamber and obtain a certain amount of energy; the smaller the absolute value of the voltage difference between the electron escape electrode 10 and the ionization chamber electrode 7, the lower the photoelectron energy; the larger the absolute value of the voltage difference between the electron escape electrode 10 and the ionization chamber electrode 7, the higher the photoelectron energy.

[0060] The gas pressure in the ionization region of the ion repeller electrode 6 and the ion ejection electrode 13 is maintained at 10 -3 Pa~10 2 Pa.

[0061] Preferably, the gas pressure in the ionization region between the ion repeller electrode 6 and the ion ejection electrode 13 is 10 -3 Pa.

[0062] The diameter of the central through hole of the ion repeller electrode 6 is 4 to 10 mm; the diameters of the ion extraction electrode 11 and the ion focusing electrode 12 are 8 to 20 mm; the diameter of the through hole of the ion extraction electrode 13 is 0.1 to 5 mm; the distance between the ion repeller electrode 6 and the ion extraction electrode 11 is 10 to 150 mm; the distance between the electron escape electrode 10 and the ion chamber electrode 7 is 0.5 to 5 mm.

[0063] Preferably, the true light ultraviolet light source 1 is a gas discharge lamp, an ultraviolet light emitting diode, a synchrotron radiation light source or a laser light source.

[0064] The electron escape electrode 10 is applied with a voltage different from that of the ionization chamber electrode 7, and the absolute value of the voltage difference does not exceed 200V.

[0065] As one of the embodiments, the voltage of the ion repeller electrode 6 is 24V; the voltage of the ion chamber electrode 7 is 8V; the voltage of the ion extraction electrode 11 is 8V; the voltage of the ion focusing electrode 12 is -50V and the voltage of the ion emission electrode 13 is 0V.

[0066] As one of the embodiments, when the voltage of the electron escape electrode 10 is higher than the voltage of the ionization chamber electrode 7, the absolute value of the voltage difference is 70V, that is, the voltage of the electron escape electrode 10 is 78V, and the photoelectrons move toward the electron escape electrode 10, collide with the electron escape electrode 10 and are annihilated, and the energy of the photoelectrons is 0.

[0067] As one of the embodiments, when the voltage of the electron escape electrode 10 is lower than the voltage of the ionization chamber electrode 7, the absolute value of the voltage difference is 70V, that is, the voltage of the lamp holder electrode 4 is -62V, and the photoelectrons move toward the center of the ionization chamber electrode 7 to obtain 70eV of energy; when the absolute value of the voltage difference between the electron escape electrode 10 and the ionization chamber electrode 7 is reduced to 50V, that is, the voltage of the electron escape electrode 10 is -42V, and the energy of the photoelectrons is reduced to 50eV; when the absolute value of the voltage difference between the electron escape electrode 10 and the ionization chamber electrode 7 is increased to 90V, that is, the voltage of the lamp holder electrode 4 is -82V, and the energy of the photoelectrons is increased to 90eV.

[0068] In summary, the laser-induced ultrasonic desorption photoelectron ionization source for mass spectrometry of the present invention comprises a laser-induced ultrasonic desorption source, a sample to be tested, an ion repeller electrode, multiple groups of ionization chamber electrodes, an ion extraction electrode, an ion focusing electrode and an ion exit electrode, and a vacuum ultraviolet light device, and has the characteristics of low detection limit, wide sample selection range, long life, and low power consumption. The present invention can not only suppress photoelectrons, but also enhance photoelectrons. By adjusting the voltage difference between the electron escape electrode and the ionization chamber electrode, the switching between the ultraviolet photoionization mode and the photoelectron ionization mode and the regulation of the photoelectron energy can be achieved.

[0069] 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.

[0070] 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 laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry, characterized in that: include: Laser-induced ultrasonic desorption source; A sample to be tested (5), an ion repeller electrode (6), a plurality of groups of ion chamber electrodes (7), an ion extraction electrode (11), an ion focusing electrode (12) and an ion emission electrode (13) are sequentially arranged on one side of the laser induced ultrasonic desorption source; A vacuum ultraviolet light device is arranged between a plurality of groups of ionization chamber electrodes (7).

2. The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry according to claim 1, characterized in that: The laser induced ultrasonic desorption source comprises: A focusing lens (3) is arranged at one end of the laser-induced ultrasonic desorption photoelectron ionization source; a substrate (4) which is spaced apart from the focusing lens (3), and a sample molecule is arranged on a side of the substrate (4) close to the focusing lens (3), and a sample to be detected (5) is arranged on a side of the substrate (4) away from the focusing lens (3); The laser (2) is focused by the focusing lens (3) and irradiated onto one side of the substrate (4) on which the sample molecules are deposited.

3. The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry according to claim 2, characterized in that: The vacuum ultraviolet light device comprises: A true ultraviolet light source (1) for emitting vacuum ultraviolet light (9); An electron escape electrode (10) is arranged at the bottom of the true ultraviolet light source (1), and the vacuum ultraviolet light (9) irradiates the electron escape electrode (10).

4. The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry according to claim 3, characterized in that: The vacuum ultraviolet light device also includes: Two insulating fixing members (8) are installed on both sides of the electron escape electrode (10).

5. The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry according to claim 4, characterized in that: The ionization chamber electrode (7) is arranged on the electron escape electrode (10), and the electron escape electrode (10) and the center of the true light ultraviolet light source (1) are on the same axis and perpendicular to the axial direction of the true light ultraviolet light source (1).

6. The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry according to claim 5, characterized in that: Two groups of ionization chamber electrodes (7) are provided, and the two groups of ionization chamber electrodes (7) are distributed on both sides of the vacuum ultraviolet light (9), and one ionization chamber electrode (7) in each group is fixed on the insulating fixing member (8).

7. The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry according to claim 5, characterized in that: The electron escape electrode (10) is in the shape of an integrated cylinder.

8. The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry according to claim 6, characterized in that: The ion repeller electrode (6), the ion extraction electrode (11), the ion focusing electrode (12) and the ion exit electrode (13) are all arranged in a group, and the ion repeller electrode (6), the ion chamber electrode (7), the ion extraction electrode (11), the ion focusing electrode (12) and the ion exit electrode (13) are all loaded with different voltages, and the ion extraction electrode (11) and the ion exit electrode (13) form a group of electrostatic lenses to eliminate ion beam spherical aberration to form a parallel ion beam.

9. The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry according to claim 2, characterized in that: The ion repeller electrode (6), multiple groups of ion chamber electrodes (7), ion extraction electrode (11), ion focusing electrode (12) and ion emission electrode (13) are all central through-hole structures, and are parallel to each other, spaced apart, and arranged coaxially with the central through-holes.

10. The laser induced ultrasonic desorption photoelectron ionization source for mass spectrometry according to claim 3, characterized in that: The ion repeller electrode (6), multiple groups of ion chamber electrodes (7), ion extraction electrode (11), ion focusing electrode (12) and ion emission electrode (13) are on the same axis as the center of the laser (2) and are perpendicular to the direction in which the true light ultraviolet light source (1) emits the vacuum ultraviolet light (9).

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