Continuous ion beam screening and enriching system and method and mass spectrometer

Abstract

The invention relates to a continuous ion beam screening and enriching system and method and a mass spectrograph, and the continuous ion beam screening and enriching system comprises a vacuum differential unit, a first ion focusing unit, a mass screening unit, a second ion focusing unit, an enriching and releasing unit and a third ion focusing unit which are sequentially arranged from upstream to downstream. The enrichment and release unit is provided with a shell and a plurality of annular electrode plates which are arranged in parallel and located in a cavity of the shell, a resistor and a capacitor are connected between every two adjacent annular electrode plates to form a gradient electric field, and center holes of the annular electrode plates are concentrically arranged to jointly form an ion channel penetrating between an inlet and an outlet of the enrichment and release unit. According to the invention, continuous ion beam low-energy-consumption enrichment and pulse release can be realized, and strict requirements of scientific and industrial fields on mass spectrum detection and ion control precision are met.

Description

Technical Field

[0001] The present invention relates to the field of mass spectrometry analysis, and particularly relates to a continuous ion beam screening and enrichment system, method and mass spectrometer. Background Art

[0002] When a continuous ion beam enters a mass spectrometer, due to factors such as the interaction between ions and collisions with background gas molecules, problems such as ion energy dispersion and signal overlap are likely to occur, thereby reducing the resolution and accuracy of mass spectrometry detection. In the commonly used continuous ion beam processing devices in the prior art, the Einzel lens method can only achieve the radial compression of the ion beam, the ion gate method has a large loss of ion beam intensity, and the flexibility and accuracy of ion beam shaping are low. The radio frequency field - DC field combination method has deficiencies in the rapid conversion of continuous ion beams to pulsed ion beams, and the ion manipulation method based on micro - nano structures cannot be stably applied on a large scale. Summary of the Invention

[0003] The present invention provides a continuous ion beam screening and enrichment system, method and mass spectrometer.

[0004] Specifically, the present invention is realized through the following technical solutions:

[0005] In a first aspect, the present invention provides a continuous ion beam screening and enrichment system, including a vacuum differential unit, a first ion focusing unit, a mass screening unit, a second ion focusing unit, an enrichment and release unit, and a third ion focusing unit arranged in sequence from upstream to downstream. The enrichment and release unit is provided with a housing and a plurality of annular electrode plates arranged in parallel in the housing chamber. Resistors and capacitors are connected between adjacent annular electrode plates to form a gradient electric field. The central holes of each annular electrode plate are concentrically arranged to jointly form an ion channel penetrating between the inlet and outlet of the enrichment and release unit. Among them, a radio frequency electric current is applied to the first annular electrode plate to the penultimate annular electrode plate, and a direct current is applied to the first annular electrode plate and the penultimate annular electrode plate, so that the applied DC voltage of the first annular electrode plate is higher than that of the penultimate annular electrode plate, and at the same time, the last annular electrode plate maintains a pulsed voltage higher than that of the penultimate annular electrode plate, thereby constraining and aggregating the continuous ion beam entering the enrichment and release unit in the enrichment and release unit, and applying a radio frequency electric current to the first annular electrode plate to the penultimate annular electrode plate, and applying a direct current to the first annular electrode plate and the penultimate annular electrode plate, and at the same time, the last annular electrode plate maintains a pulsed voltage lower than that of the penultimate annular electrode plate, thereby enabling the ions to leave the enrichment and release unit.

[0006] In some embodiments, an air inlet is provided on the housing of the enrichment and release unit for filling a cooling gas into the housing chamber.

[0007] In some embodiments, the housing is made of a metallic material.

[0008] In some embodiments, the vacuum differential unit is provided with a support element and a cone structure supported by the support element. The support element is made of an insulating material. The small-end hole of the cone structure faces the upstream ion source, and the large-end opening of the cone structure faces the downstream first ion focusing unit. An electric field is applied to the cone structure to achieve ion screening, vacuum differential, and collimation of the ion beam operation.

[0009] In some embodiments, the mass screening unit is selected from a quadrupole mass analyzer, a sector magnetic field mass analyzer, or a magnetic and electric double-focusing mass analyzer.

[0010] In some embodiments, the first ion focusing unit, the second ion focusing unit, and the third ion focusing unit are each provided with a plurality of annular electrode plates arranged in parallel. The numbers of annular electrode plates of the first ion focusing unit, the second ion focusing unit, and the third ion focusing unit are 3, 3, and 6 annular electrode plates respectively.

[0011] In some embodiments, the plurality of annular electrode plates of the enrichment and release unit are arranged with equal thickness d1 and equal spacing I, where d1 = I. The inner diameter of the central hole of the annular electrode plate gradually decreases from the inlet to the outlet, and the minimum inner diameter d2 > 4d1.

[0012] In some embodiments, the vacuum differential unit is fixedly connected to the first annular electrode plate of the first ion focusing unit, so that the floating ground voltage of the first ion focusing unit is equal to the voltage of the vacuum differential unit; and / or, the distance between the first ion focusing unit and the mass screening unit is less than 30 mm, the distance between the mass screening unit and the second ion focusing unit is less than 10 mm, the distance between the second ion focusing unit and the enrichment and release unit is less than 15 mm, and the distance between the enrichment and release unit and the third ion focusing unit is less than 30 mm.

[0013] In a second aspect, the present invention provides a method for continuous ion beam screening and enrichment, using the continuous ion beam screening and enrichment system described in the first aspect. The method for continuous ion beam screening and enrichment is characterized in that it includes vacuum differential, first ion focusing, mass screening, second ion focusing, enrichment and release, and third ion focusing. Among them, the enrichment and release includes:

[0014] Ion aggregation, applying a radio frequency electric current to the first annular electrode plate to the penultimate annular electrode plate in the enrichment and release unit, and applying a direct current to the first annular electrode plate and the penultimate annular electrode plate, so that the applied direct current voltage of the first annular electrode plate is higher than that of the penultimate annular electrode plate, and at the same time, maintaining a pulsed voltage higher than that of the penultimate annular electrode plate on the last annular electrode plate, thereby constraining and enriching the continuous ion beam entering the enrichment and release unit in the enrichment and release unit;

[0015] Ion release: Apply radio frequency electricity to the first to the penultimate annular electrode sheets in the enrichment and release unit, apply direct current electricity to the first and the penultimate annular electrode sheets, and at the same time maintain a pulsed voltage on the last annular electrode sheet that is lower than that of the penultimate annular electrode sheet, so as to enable ions to leave the enrichment and release unit.

[0016] In a third aspect, the present invention provides a mass spectrometer, which includes an ion source, a detector, and the continuous ion beam screening and enrichment system described in the first aspect. A vacuum differential unit is located downstream of the ion source, and a third ion focusing unit is located upstream of the detector.

[0017] According to the present invention, by controlling multiple annular electrode sheets in the enrichment and release unit with radio frequency electricity, direct current electricity, and pulsed electricity, continuous ion beam low-energy consumption enrichment and pulsed release can be achieved. Through the collaborative work of each unit, ions can be precisely controlled, focused, enriched, and pulsed released throughout the process, which can meet the strict requirements for mass spectrometry detection and ion manipulation accuracy in the scientific and industrial fields.

[0018] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit this application. Description of the Drawings

[0019] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application.

[0020] Figure 1 is a schematic diagram of the continuous ion beam screening and enrichment system in an embodiment of the present invention;

[0021] Figure 2 is the time-of-flight mass spectrometry diagram of the continuous Au + ion beam before and after screening and enrichment;

[0022] Figure 3 is a series of continuous mass spectrometry diagrams of the cluster ion beam after screening and enrichment in an embodiment of the present invention.

[0023] Reference Signs:

[0024] 1: Vacuum differential unit; 2: First ion focusing unit; 3: Mass screening unit; 4: Second ion focusing unit; 5: Enrichment and release unit; 6: Housing; 7: Annular electrode sheet; 8: Third ion focusing unit. Detailed Embodiments

[0025] The present disclosure will now be described with reference to several embodiments. It should be understood that the description of these embodiments is only for enabling those of ordinary skill in the art to better understand and thus implement the present disclosure, rather than implying any limitation to the scope of the present disclosure.

[0026] As used herein, the term "comprising" and its variants are to be construed as open-ended terms meaning "including but not limited to"; the terms "embodiment" and "an embodiment" are to be construed as "at least one embodiment"; the term "another embodiment" is to be construed as "at least one other embodiment"; the terms "first", "second", etc. may refer to different or the same objects; the term "arranged" is not limited to direct connection or indirect connection, nor to a specific connection manner. There may also be other explicit and implicit definitions hereinafter.

[0027] In the following description, some specific numerical values or numerical ranges may be involved. It should be understood that these numerical values and numerical ranges are merely exemplary and may be conducive to putting the idea of the present disclosure into practice. However, the description of these examples is not intended to limit the scope of the present disclosure in any way. According to specific application scenarios and requirements, these numerical values or numerical ranges can be set otherwise.

[0028] As described above, the continuous ion beam processing devices of the prior art cannot simultaneously meet the requirements such as axial compression, low loss, high shaping flexibility and high precision, and large-scale stable application. The continuous ion beam screening and enrichment system, method and mass spectrometer proposed by the embodiments of the present invention at least partially solve the above problems. As Figure 1 shown, the continuous ion beam screening and enrichment system of the embodiments of the present invention generally includes a vacuum differential unit, a first ion focusing unit, a mass screening unit, a second ion focusing unit, an enrichment and release unit, and a third ion focusing unit. The vacuum differential unit is located at the most upstream, the third ion focusing unit is located at the most downstream, and the remaining units are arranged in sequence between the vacuum differential unit and the third ion focusing unit.

[0029] The vacuum differential unit is used to perform ion screening, vacuum differential and ion beam collimation on the ion beam from the ion source, and remove the interference of stray ions and gas molecules. In one embodiment, the vacuum differential unit is provided with a support element and a cone structure, and the support element is used to provide support for the cone structure. Exemplarily, the support element is made of an insulating material, which can ensure the electrical stability and safety of the cone structure.

[0030] The cone structure is formed with a small end hole located on the small diameter side of the cone and a large end opening located on the large diameter side of the cone. Among them, the small end hole faces the upstream ion source, and the large end opening faces the downstream first ion focusing unit, and an electric field is applied to the cone structure to realize ion screening, vacuum differential and ion beam collimation operations.

[0031] The first ion focusing unit, the second ion focusing unit, and the third ion focusing unit are all used to focus the ion beam. Among them, the first ion focusing unit is located upstream of the mass screening unit, and the second ion focusing unit is located downstream of the mass screening unit. The first ion focusing unit is used to initially focus the continuous ion beam to make the ion beam more concentrated, so as to perform mass screening more accurately subsequently. The ions after screening enter the second ion focusing unit for re-focusing to further improve the density and energy uniformity of the ions, and then the ion beam enters the enrichment and release unit.

[0032] In one embodiment, the first ion focusing unit, the second ion focusing unit, and the third ion focusing unit are all provided with a plurality of annular electrode plates arranged in parallel. Each ion focusing unit forms an ion focusing mirror by applying different voltages on different annular electrode plates, so as to improve the focusing efficiency of the continuous ion beam. Exemplarily, the first ion focusing unit is provided with 3 annular electrode plates, and the second ion focusing unit is provided with 3 annular electrode plates, which can meet the requirements of ion focusing upstream and downstream of the mass screening unit. The third ion focusing unit is provided with 6 annular electrode plates, so that through the last focusing, it can be ensured that the ions enter the detector of the mass spectrometer in the best state, improving the accuracy and sensitivity of detection.

[0033] The mass screening unit is used to screen out specific mass ions with desired mass-to-charge ratio. The screened ions enter the second ion focusing unit for further ion focusing operation. In one embodiment, the mass screening unit can select a quadrupole mass analyzer, a sector magnetic field mass analyzer, or a magnetic and electric double focusing mass analyzer. Exemplarily, a quadrupole mass analyzer is selected.

[0034] In one embodiment, the vacuum differential unit is fixedly connected to the first annular electrode plate at the inlet of the first ion focusing unit, so that the floating ground voltage of the first ion focusing unit is equal to the voltage of the vacuum differential unit.

[0035] The enrichment and release unit is used to aggregate and pulse-release charged ions. The enrichment and release unit is provided with a housing and a plurality of annular electrode plates arranged in parallel. The plurality of annular electrode plates are located in the hollow chamber of the housing, and a resistor and a capacitor are connected between adjacent annular electrode plates, so as to form a gradient electric field between adjacent annular electrode plates. Exemplarily, the housing is made of a metal material, which can play a role in shielding the electric field and increasing the residence time of the cooling gas.

[0036] The central holes of each annular electrode sheet of the enrichment and release unit are concentrically arranged, and all the central holes together form the ion channel of the enrichment and release unit. Among them, the upstream side of the ion channel is the inlet of the enrichment and release unit, and the downstream side is the outlet of the enrichment and release unit. The annular electrode sheet closest to the inlet is defined as the first annular electrode sheet, and the annular electrode sheet closest to the outlet is defined as the last annular electrode sheet. In one embodiment, the multiple annular electrode sheets are arranged with equal thickness, the thickness of each annular electrode sheet is d1, the multiple annular electrode sheets are arranged at equal intervals, and the interval between adjacent annular electrode sheets is I, such that d1 = I, and the inner diameter of the central hole of the annular electrode sheet gradually decreases from the inlet to the outlet, with the minimum inner diameter d2 > 4d1 to ensure that ions can be discharged in large quantities and quickly concentrated. Exemplarily, "gradually decreasing" can be a segmented decrease as Figure 1 shown, that is, the inner diameter of the central hole of the annular electrode sheet in the first section close to the inlet is constant, and the inner diameter of the central hole of the annular electrode sheet in the second section close to the outlet shows a decreasing trend.

[0037] In one embodiment, an air inlet is provided on the housing of the enrichment and release unit for filling the cooling gas into the chamber of the housing, so as to keep the ions entering the enrichment and release unit cooled.

[0038] In one embodiment, by optimizing the distance between each unit, an efficient continuous ion beam screening and enrichment effect can be achieved. Exemplarily, the distance between the first ion focusing unit and the mass screening unit is less than 30 mm, the distance between the mass screening unit and the second ion focusing unit is less than 10 mm, the distance between the second ion focusing unit and the enrichment and release unit is less than 15 mm, and the distance between the enrichment and release unit and the third ion focusing unit is less than 30 mm.

[0039] When using the continuous ion beam screening and enrichment system of the embodiment of the present invention, the continuous ion beam emitted by the ion source is first subjected to ion screening, vacuum differential and ion beam collimation by the vacuum differential unit, then subjected to primary ion aggregation by the first ion focusing unit, and then subjected to secondary ion focusing after mass screening. After the ion beam is aggregated and pulse-released in the enrichment and release unit, and then finally ion focused, a sufficiently accurate ion detection and analysis effect can be obtained.

[0040] For the electrical control of the annular electrode sheet of the enrichment and release unit, first, a radio frequency electric current is simultaneously applied to the first annular electrode sheet to the penultimate annular electrode sheet in the enrichment and release unit, and a direct current is applied to the first annular electrode sheet and the penultimate annular electrode sheet, such that the applied direct current voltage of the first annular electrode sheet is higher than that of the penultimate annular electrode sheet. Exemplarily, a voltage of 1 - 20 V is applied to the first annular electrode sheet and the penultimate annular electrode sheet.

[0041] Next, a pulsed electric current with a relatively high voltage is applied to the last annular electrode sheet, so as to confine ions in the chamber of the enrichment and release unit, realizing the ion aggregation function. In another embodiment, a cooling gas can be simultaneously introduced into the chamber of the enrichment and release unit to cool the ions, ensuring that the ions are better aggregated in the chamber of the enrichment and release unit.

[0042] Finally, after the pulsed electric current ends, the last annular electrode sheet is maintained at a pulsed voltage lower than that of the penultimate annular electrode, enabling the ions to leave the enrichment and release unit, realizing the ion pulsed release function. Exemplarily, a pulsed electric current of 20V is applied to the first annular electrode sheet, and the last annular electrode sheet is maintained at a voltage of 0V.

[0043] An embodiment of the present invention further provides a mass spectrometer, including an ion source, a detector, and a continuous ion beam screening and enrichment system. The vacuum differential unit is located downstream of the ion source, and the third ion aggregation unit is located upstream of the detector.

[0044] Using the continuous ion beam screening and enrichment system of the embodiment of the present invention to process the continuous ion beam of Au n (n = 1 - 20), as Figure 2 shown, the detected ion signal intensity is increased by 100 times; as Figure 3 shown, the mass spectrometry diagram of the cluster ion beam after screening and enrichment.

[0045] In the description of the embodiments herein, any reference to directions and orientations is only for the convenience of description and should not be construed as any limitation to the protection scope of the present invention. The description of the preferred embodiments involves combinations of features, and these features may exist independently or in combination. The present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0046] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A continuous ion beam screening and enrichment system, characterized in that It includes a vacuum differential unit, a first ion focusing unit, a mass screening unit, a second ion focusing unit, an enrichment and release unit, and a third ion focusing unit arranged in sequence from upstream to downstream. The enrichment and release unit is provided with a housing and a plurality of annular electrode plates arranged in parallel in the housing chamber. A resistor and a capacitor are connected between adjacent annular electrode plates to form a gradient electric field. The central holes of each annular electrode plate are concentrically arranged to jointly form an ion channel penetrating between the inlet and outlet of the enrichment and release unit. Among them, radio frequency electricity is applied to the first annular electrode plate to the penultimate annular electrode plate, and direct current electricity is applied to the first annular electrode plate and the penultimate annular electrode plate, so that the direct current voltage applied to the first annular electrode plate is higher than that of the penultimate annular electrode plate. At the same time, the last annular electrode plate is maintained at a pulsed voltage higher than that of the penultimate annular electrode plate, so as to confine and focus the continuous ion beam entering the enrichment and release unit in the enrichment and release unit. And radio frequency electricity is applied to the first annular electrode plate to the penultimate annular electrode plate, and direct current electricity is applied to the first annular electrode plate and the penultimate annular electrode plate. At the same time, the last annular electrode plate is maintained at a pulsed voltage lower than that of the penultimate annular electrode plate, so that ions leave the enrichment and release unit.

2. The continuous ion beam screening and enrichment system according to claim 1, wherein An air inlet is provided on the housing of the enrichment and release unit for filling a cooling gas into the housing chamber.

3. The continuous ion beam screening and enrichment system according to claim 1, wherein The housing is made of a metal material.

4. The continuous ion beam screening and enrichment system according to claim 1, characterized in that, The vacuum differential unit is provided with a support element and a cone structure supported by the support element. The support element is made of an insulating material. The small end hole of the cone structure faces the upstream ion source, and the large end opening of the cone structure faces the downstream first ion focusing unit. An electric field is applied to the cone structure to achieve ion screening, vacuum differential, and collimation of the ion beam operation.

5. The continuous ion beam screening and enrichment system according to claim 1, wherein The mass screening unit is selected from a quadrupole mass analyzer, a sector magnetic field mass analyzer, or a magnetic and electric double focusing mass analyzer.

6. The continuous ion beam screening and enrichment system according to claim 1, wherein The first ion focusing unit, the second ion focusing unit, and the third ion focusing unit are all provided with a plurality of annular electrode plates arranged in parallel. The numbers of annular electrode plates of the first ion focusing unit, the second ion focusing unit, and the third ion focusing unit are 3, 3, and 6 annular electrode plates respectively.

7. The continuous ion beam screening and enrichment system according to claim 1, wherein, The plurality of annular electrode plates of the enrichment and release unit are arranged with equal thickness d1 and equal spacing I, and d1 = I. Among them, the inner diameter of the central hole of the annular electrode plate gradually decreases from the inlet to the outlet, and the minimum inner diameter d2 > 4d1.

8. The continuous ion beam screening and enrichment system according to claim 1, characterized in that The vacuum differential unit is fixedly connected to the first annular electrode plate of the first ion focusing unit, so that the floating ground voltage of the first ion focusing unit is equal to the voltage of the vacuum differential unit; and / or, the distance between the first ion focusing unit and the mass screening unit is less than 30 mm, the distance between the mass screening unit and the second ion focusing unit is less than 10 mm, the distance between the second ion focusing unit and the enrichment and release unit is less than 15 mm, and the distance between the enrichment and release unit and the third ion focusing unit is less than 30 mm.

9. A continuous ion beam screening and enrichment method, using the continuous ion beam screening and enrichment system according to any one of claims 1-8, characterized in that, The continuous ion beam screening and enrichment method includes vacuum differential, first ion focusing, mass screening, second ion focusing, enrichment and release, and third ion focusing. Among them, the enrichment and release includes: Ion aggregation: Apply radio frequency electricity to the first to the penultimate annular electrode sheets in the enrichment and release unit, and apply direct current electricity to the first and penultimate annular electrode sheets, so that the applied direct current voltage of the first annular electrode sheet is higher than that of the penultimate annular electrode sheet. At the same time, maintain a pulsed voltage on the last annular electrode sheet that is higher than that of the penultimate annular electrode sheet, thereby constraining and enriching the continuous ion beam entering the enrichment and release unit within the enrichment and release unit; Ion release: Apply radio frequency electricity to the first to the penultimate annular electrode sheets in the enrichment and release unit, and apply direct current electricity to the first and penultimate annular electrode sheets. At the same time, maintain a pulsed voltage on the last annular electrode sheet that is lower than that of the penultimate annular electrode sheet, thereby enabling the ions to leave the enrichment and release unit.

10. A mass spectrometer, characterized in that, Comprising an ion source and a continuous ion beam screening and enrichment system as described in any one of claims 1-8, with a vacuum differential unit located downstream of the ion source.

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