Novel off-axis high-order field ion funnel transmission system and voltage loading method thereof

Abstract

The application relates to the technical field of mass spectrum analysis testing, in particular to a novel off-axis high-order field ion funnel transmission system and a voltage loading method thereof, which comprises a vacuum chamber, a plurality of rod-shaped electrodes and a top-opened collecting cavity arranged inside the vacuum chamber, the collecting cavity is arranged below the rod-shaped electrodes, the vacuum chamber is provided with an inlet, an ion outlet and a discharge outlet, the plurality of rod-shaped electrodes are arranged in a spaced manner along the circumference to form an open rod array ion transmission channel; the open rod array ion transmission channel is provided with an inlet section, a transition section and an outlet section which are sequentially connected along the transmission direction, the inlet section is connected with the inlet, the outlet section is connected with the ion outlet, and the central axis of the transition section is gradually upwardly offset; the discharge outlet is arranged below the ion outlet, and the central axis of the discharge outlet is aligned with the central axis of the inlet. Neutral substances, solvent droplets, clusters and particulate impurities are shunted and discharged, the maintenance frequency is significantly reduced, and the wide mass range transmission and focusing capacity are effectively guaranteed.

Description

Technical Field

[0001] This invention relates to the field of mass spectrometry analysis and testing technology, and in particular to a novel off-axis high-order field ion funnel transport system and its voltage loading method. Background Technology

[0002] Mass spectrometers typically require the transfer of ions from an ion source or vacuum differential interface from a higher pressure region to a lower pressure mass analysis region. The ion plume introduced by the ion source is usually accompanied by a large amount of neutral substances, solvent droplets and their clusters, particulate impurities, etc. If these substances enter the subsequent ion optical elements or mass analysis region along the same straight path, they can easily cause electrode contamination, discharge or static electricity accumulation, increased background noise, decreased sensitivity, and increased maintenance frequency.

[0003] Existing technologies utilize curved ion guides to block neutral substances, solvent droplets and their clusters, and particulate impurities from entering the mass analysis area. However, some solvent droplets and their clusters, as well as particulate impurities, adhere to the inner wall of the ion guide and may even accumulate on the inner wall of the vacuum chamber, resulting in contamination and preventing an effective reduction in maintenance frequency. Furthermore, curved ion guides can also affect ion transport and focusing efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a novel off-axis high-order field ion funnel transport system and its voltage loading method, which has a simple structural design, can divert and discharge neutral substances, solvent droplets and their clusters, and particulate impurities, significantly reduces the maintenance frequency, and effectively guarantees wide mass range transport and focusing capabilities.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: a novel off-axis high-order field ion funnel transport system, including a vacuum chamber having an inlet and an ion outlet; further including multiple rod-shaped electrodes installed inside the vacuum chamber and a top-opening collection cavity, the collection cavity being located below the rod-shaped electrodes; the multiple rod-shaped electrodes are arranged circumferentially at intervals to form an open rod array ion transport channel; the open rod array ion transport channel has an inlet section, a transition section, and an outlet section connected sequentially along the transport direction, the inlet section being connected to the inlet, the outlet section being connected to the ion outlet, and the central axis of the transition section gradually shifting upward; an outlet is provided on the vacuum chamber, the outlet being located below the ion outlet, and the central axis of the outlet being aligned with the central axis of the inlet; adjacent rod-shaped electrodes are applied with radio frequency voltages of opposite phase, the inlet section, the transition section, and the outlet section are respectively applied with progressively varying DC voltages, and a differential upward bias voltage matching the polarity of the target ion is applied between the upper and lower rod-shaped electrodes in the transition section.

[0006] Furthermore, the equivalent radius of the inner envelope of the inlet segment and / or transition segment and / or outlet segment gradually decreases along the transmission direction.

[0007] Furthermore, it also includes a local guide member disposed inside the vacuum chamber, wherein the connecting end of the local guide member is connected to the bottom end of the outlet, and the free end of the local guide member extends downward into the collection chamber.

[0008] Furthermore, the connecting end of the local guide is threadedly connected to the bottom end of the outlet by bolts.

[0009] Furthermore, a drain port is provided on the vacuum chamber, and the drain port is connected to the collection chamber.

[0010] Furthermore, the vacuum chamber is provided with an air extraction port, which is connected to the collection chamber.

[0011] Furthermore, the central axis of the inlet is located below the central axis of the inlet section, and the central axis of the ion outlet is located below the central axis of the outlet section.

[0012] Furthermore, the rod-shaped electrode is a cylindrical rod, a semi-cylindrical rod, a hyperboloid rod, or a flat rod.

[0013] Furthermore, the number of rod-shaped electrodes is set to six, eight, or at least twelve.

[0014] A novel voltage loading method for off-axis high-order field ion funnel transport, applicable to the aforementioned novel off-axis high-order field ion funnel transport system, includes the following steps:

[0015] Radio frequency voltages with opposite phases are applied to adjacent rod electrodes to form a higher-order radial confinement field;

[0016] A gradually varying DC voltage is applied to the inlet, transition, and outlet sections of the open-type rod array ion transport channel to form an axial DC gradient.

[0017] A differential upward bias voltage matching the polarity of the target ion is applied between the upper and lower rod-shaped electrodes in the transition section to form an electric field that causes the target ion to deflect upward.

[0018] The beneficial effects of this invention are:

[0019] (1) In the transition section of the present invention, a differential upward bias voltage matching the polarity of the target ion is applied between the upper rod electrode and the lower rod electrode, so that the target ion is transmitted and focused along the open rod array ion transmission channel of the upward bias axis. Since the neutral substance, solvent droplets and their clusters and particulate impurities cannot be guided by the radio frequency voltage, axial DC gradient and differential upward bias voltage like the target ion, that is, they are not effectively guided by the electric field, so the neutral substance, solvent droplets and their clusters and particulate impurities pass through the gap between the adjacent rod electrodes along the axial direction of the inlet and enter the outlet, and are directly discharged from the vacuum chamber from the outlet. The excessively heavy solvent droplets and their clusters and particulate impurities fall into the collection chamber by their own weight, are collected by the collection chamber and discharged from the vacuum chamber, thereby realizing the diversion and discharge of neutral substance, solvent droplets and their clusters and particulate impurities, avoiding their contamination of the open rod array ion transmission channel and the vacuum chamber, and significantly reducing the maintenance frequency of the entire system.

[0020] (2) In this invention, the equivalent radius of the inner envelope of the inlet section and / or the transition section and / or the outlet section gradually decreases along the transmission direction, achieving funnel-shaped focusing while separating ions off-axis, thus taking into account both the inlet ion receiving capability and the outlet focusing capability, and effectively ensuring the transmission and focusing capability of a wide quality range.

[0021] (3) The present invention provides a local guide at the bottom of the outlet, and the free end of the local guide extends downward into the collection chamber to intercept or guide some of the excessively heavy solvent droplets and their clusters and particulate impurities, so as to avoid some of the excessively heavy solvent droplets and their clusters and particulate impurities from contacting the side wall of the vacuum chamber below the outlet due to the long falling path, thereby further avoiding contamination of the vacuum chamber. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a cross-sectional view of the invention.

[0024] Figure 2 This is an axial cross-sectional view of the open rod array ion transport channel in this invention.

[0025] Figure 3 This is a schematic diagram of the RF phase of the open rod array ion transport channel (six rod electrodes) in this invention.

[0026] In the diagram: 100, vacuum chamber; 110, inlet; 120, ion outlet; 130, discharge outlet; 140, drain outlet; 150, evacuation port; 200, rod-shaped electrode; 300, collection chamber; 400, open rod array ion transmission channel; 410, inlet section; 420, transition section; 430, outlet section; 500, local flow guide. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0028] Example 1

[0029] like Figure 1 and Figure 2As shown, a novel off-axis high-order field ion funnel transport system is positioned in a low-vacuum differential region between an ion source and a mass analyzer. It includes a vacuum chamber 100, multiple rod-shaped electrodes 200 installed inside the vacuum chamber 100, and a top-opening collection chamber 300. The collection chamber 300 is located below the rod-shaped electrodes 200 and is used to collect excess solvent droplets and their clusters and particulate impurities. The vacuum chamber 100 has an inlet 110, an ion outlet 120, and a discharge outlet 130. The discharge outlet 130 is located at the ion outlet 110. Below 20, an outlet space separation is formed; the central axis of the outlet 130 is aligned with the central axis of the inlet 110; multiple rod-shaped electrodes 200 are arranged circumferentially to form an open rod array ion transport channel 400, with open gaps between adjacent rod-shaped electrodes 200 allowing neutral substances, solvent droplets and their clusters, and particulate impurities to pass through; the open rod array ion transport channel 400 has an inlet section 410, a transition section 420, and an outlet section 430 connected sequentially along the transport direction. The inlet section 410 is connected to the inlet 110 and receives the ion plume from the ion source or interface; the outlet section 430 is connected to the ion outlet 120 and outputs the focused ion beam to the subsequent ion optical system; the central axis of the transition section 420 gradually shifts upward, gradually guiding the ions from the inlet section 410 to the outlet section 430 along the transport direction; adjacent rod-shaped electrodes 200 are applied with radio frequency voltages of opposite phase to form a higher-order radial confinement field; the inlet section 410, the transition section 420, and the outlet section 430 are respectively loaded with progressively varying DC voltages to form an axial direct current field. A flow gradient drives the target ions to move along the transmission direction. For example, the inlet section 410 is loaded with a first DC voltage U1, the transition section 420 is loaded with a second DC voltage U2, and the outlet section 430 is loaded with a third DC voltage U3. U1, U2, and U3 decrease step by step along the transmission direction. In the transition section 420, a differential upward bias voltage matching the polarity of the target ions is applied between the upper rod electrode 200 and the lower rod electrode 200, so that the ion path actively rises, rather than relying solely on mechanical bending, tilting arrangement, or simple line of sight obstruction. For both positive and negative ion modes, the polarity or amplitude of the differential upward bias voltage is adjusted to ensure that charged particles of different polarities enter the outlet section 430 along the transition section 420. In positive ion mode, the DC potential of the lower rod electrode 200 is higher than that of the upper rod electrode 200 to create an electric field that causes positive ions to deflect upward. In negative ion mode, the DC potential of the upper rod electrode 200 is higher than that of the lower rod electrode 200, or the bias polarity is adjusted in the opposite direction to cause negative ions to deflect upward.

[0030] In the transition section 420, a differential upward bias voltage matching the polarity of the target ion is applied between the upper and lower rod-shaped electrodes 200. This causes the target ion to be transported and focused along the open rod array ion transport channel 400 on the upward bias axis. Since neutral substances, solvent droplets and their clusters, and particulate impurities cannot be guided by the combined effects of the radio frequency voltage, axial DC gradient, and differential upward bias voltage like the target ion, they are not effectively guided by the electric field. Consequently, neutral substances, solvent droplets and their clusters, and particulate impurities are not effectively guided by the electric field. The solvent enters the outlet 130 through the gap between adjacent rod electrodes 200 along the axial direction of the inlet 110, and is directly discharged from the vacuum chamber 100 through the outlet 130. Excessively heavy solvent droplets and their clusters and particulate impurities fall into the collection chamber 300 by their own weight, are collected by the collection chamber 300 and discharged from the vacuum chamber 100. This achieves the diversion and discharge of neutral substances, solvent droplets and their clusters and particulate impurities, avoiding their contamination of the open rod array ion transport channel 400 and the vacuum chamber 100, and significantly reducing the maintenance frequency of the entire system.

[0031] Specifically, the vacuum chamber 100 adopts an existing structure, which will not be described in detail here. The central axis of the inlet 110 is located below the central axis of the inlet section 410, reducing the falling height of excessively heavy solvent droplets and their clusters, particulate impurities, and providing space for the outlet 130 and the collection chamber 300. The central axis of the ion outlet 120 is located below the central axis of the outlet section 430. The rod-shaped electrode 200 is formed by a continuous curved rod, or by multiple short rods arranged in an upward curve or segmented broken line. The rod-shaped electrode 200 is positioned inside the vacuum chamber 100 by an insulating support, electrode positioning component, or shielding shell (not shown in the figure). The insulating support, electrode positioning component, or shielding shell is provided with a clearance window to reduce obstruction to the emission path of neutral substances, solvent droplets and their clusters, and particulate impurities. The number of rod-shaped electrodes 200 is preferably six, eight, or twelve, but more than twelve can also be used to form hexapole, octapole, dodecapole, or higher-order constraint fields, respectively. A six-bar structure facilitates compact arrangement, an eight-bar structure is beneficial for obtaining a relatively gentle central field, and a twelve-bar or more structure is beneficial for forming a flatter central effective potential and widening the mass range. The rod-shaped electrodes 200 are preferably cylindrical rods, semi-cylindrical rods, hyperboloid rods, flat rods, or combinations thereof. The central axis of the transition section 420 is preferably offset upwards in a straight line, an arc, an S-shape, or a segmented broken line.

[0032] like Figure 3 As shown, taking six rod-shaped electrodes 200 as an example, the odd-numbered rod-shaped electrodes 200 are loaded with RF+, and the even-numbered rod-shaped electrodes 200 are loaded with RF-. In the transition section 420, a differential upward bias voltage matching the polarity of the target ion is applied between the upper rod-shaped electrodes 200 (numbered 1, 2 and 6) and the lower rod-shaped electrodes 200 (numbered 3, 4 and 5).

[0033] In one feasible embodiment, the inner envelope equivalent radius of the inlet section 410 and / or the transition section 420 and / or the outlet section 430 gradually decreases along the transmission direction, achieving funnel-shaped focusing while separating ions off-axis, thereby taking into account both the inlet ion receiving capability and the outlet focusing capability, and effectively ensuring the transmission and focusing capability over a wide quality range.

[0034] Specifically, the equivalent radius of the inner envelope gradually decreases along the transmission direction using overall linear tapering, overall nonlinear tapering, or overall segmented tapering. The entrance section 410 can be a larger constant-diameter section or a slightly tapered section, the transition section 420 can be the main tapered section, and the exit section 430 can be a smaller constant-diameter section or a slightly tapered section. As long as the overall equivalent radius of the inner envelope of the entrance section 410 is greater than the equivalent radius of the inner envelope of the exit section 430, a funnel-shaped focusing effect can be achieved.

[0035] The combined effects of the high-order field, funnel-shaped focusing, and upward-biased path enable the system to achieve ion capture, focusing, and pollutant separation.

[0036] In another embodiment, such as Figure 1 As shown, a local guide 500 is provided inside the vacuum chamber 100. The connecting end of the local guide 500 is connected to the bottom end of the outlet 130, and the free end of the local guide 500 extends downward into the collection chamber 300.

[0037] A local guide 500 is provided at the bottom of the outlet 130, and the free end of the local guide 500 extends downward into the collection chamber 300. This is used to intercept or guide some of the excessively heavy solvent droplets and their clusters and particulate impurities, so as to prevent some of the excessively heavy solvent droplets and their clusters and particulate impurities from contacting the side wall of the vacuum chamber 100 below the outlet 130 due to the long falling path, thereby further preventing contamination of the vacuum chamber 100.

[0038] Specifically, the connecting end of the local guide component 500 is connected to the bottom thread of the outlet 130 by bolts, so as to realize the detachable connection of the local guide component 500 and facilitate the replacement of the local guide component 500.

[0039] In this embodiment, as Figure 1 As shown, a drain port 140 is provided on the vacuum chamber 100. The drain port 140 is connected to the collection chamber 300 and is used to discharge the solvent droplets and their clusters and particulate impurities collected in the collection chamber 300.

[0040] Specifically, the drain outlet 140 is connected to a waste liquid collector (not shown in the figure), and a valve is installed on the drain outlet 140 to control the opening and closing.

[0041] In this embodiment, as Figure 1As shown, the vacuum chamber 100 is provided with an exhaust port 150, which is connected to the collection chamber 300 to further guide the excessively heavy solvent droplets and their clusters and particulate impurities into the collection chamber 300.

[0042] Specifically, the exhaust port 150 is located on the left side wall of the vacuum chamber 100. The exhaust port 150 can be connected to the exhaust pipeline of the existing vacuum level, or connected to the exhaust pump through a throttle orifice, regulating valve, and collector.

[0043] The ion outlet 120 of this system can be connected to subsequent ion guides, ion lenses, quadrupole mass analyzers, time-of-flight mass analyzers, ion traps, or other mass analysis components. This system is suitable for electrospray ionization sources, APCI ion sources, MALDI interfaces, ICP interfaces, or other mass spectrometry sample introduction systems that require the separation of ions and neutral contaminants in a vacuum differential region.

[0044] Example 2

[0045] A novel off-axis high-order field ion funnel transport voltage loading method, applicable to the novel off-axis high-order field ion funnel transport system in Example 1, includes the following steps:

[0046] Radio frequency voltages with opposite phases are applied to adjacent rod electrodes 200 to form a higher-order radial confinement field;

[0047] A gradually varying DC voltage is applied to the inlet section 410, transition section 420 and outlet section 430 of the open rod array ion transport channel 400 to form an axial DC gradient.

[0048] A differential upward bias voltage matching the polarity of the target ion is applied between the upper rod electrode 200 and the lower rod electrode 200 in the transition section 420 to form an electric field that causes the target ion to deflect upward.

[0049] Under the combined action of the aforementioned voltages, charged particles are transported and focused along the open rod array ion transport channel 400 of the upward deflection axis and enter the ion outlet 120.

[0050] Specifically, at least one of the following parameters is adjusted based on the target ion's mass-to-charge ratio range, gas pressure conditions, or target transmission efficiency: radio frequency amplitude, radio frequency, axial DC gradient voltage, and differential upward bias voltage.

[0051] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A novel off-axis high-order field ion funnel transport system, comprising a vacuum chamber (100) having an inlet (110) and an ion outlet (120); characterized in that, It also includes a plurality of rod-shaped electrodes (200) installed inside a vacuum chamber (100) and a collection cavity (300) with an open top, the collection cavity (300) being disposed below the rod-shaped electrodes (200); the plurality of rod-shaped electrodes (200) are arranged circumferentially at intervals to form an open rod array ion transport channel (400); the open rod array ion transport channel (400) has an inlet section (410), a transition section (420) and an outlet section (430) connected sequentially along the transport direction, the inlet section (410) being connected to the inlet (110), the outlet section (430) being connected to the ion outlet (120), the transition section (420) being connected to the ... The central axis of the vacuum chamber (100) gradually shifts upward; an outlet (130) is provided on the vacuum chamber (100), the outlet (130) is located below the ion outlet (120), and the central axis of the outlet (130) is aligned with the central axis of the inlet (110); radio frequency voltages with opposite phases are applied to adjacent rod electrodes (200), and DC voltages that change stepwise are applied to the inlet section (410), the transition section (420) and the outlet section (430), respectively. A differential upward bias voltage matching the polarity of the target ion is applied between the upper rod electrode (200) and the lower rod electrode (200) in the transition section (420).

2. The novel off-axis high-order field ion funnel transport system according to claim 1, characterized in that, The equivalent radius of the inner envelope of the inlet segment (410) and / or transition segment (420) and / or outlet segment (430) gradually decreases along the transmission direction.

3. The novel off-axis high-order field ion funnel transport system according to claim 1, characterized in that, It also includes a local guide (500) disposed inside the vacuum chamber (100), the connecting end of the local guide (500) being connected to the bottom end of the outlet (130), and the free end of the local guide (500) extending downward into the collection chamber (300).

4. The novel off-axis high-order field ion funnel transport system according to claim 3, characterized in that, The connecting end of the local guide (500) is threadedly connected to the bottom end of the outlet (130) by bolts.

5. The novel off-axis high-order field ion funnel transport system according to claim 1, characterized in that, The vacuum chamber (100) is provided with a drain port (140), which is connected to the collection chamber (300).

6. The novel off-axis high-order field ion funnel transport system according to claim 1, characterized in that, The vacuum chamber (100) is provided with an air extraction port (150), which is connected to the collection chamber (300).

7. The novel off-axis high-order field ion funnel transport system according to claim 1, characterized in that, The central axis of the inlet (110) is located below the central axis of the inlet section (410), and the central axis of the ion outlet (120) is located below the central axis of the outlet section (430).

8. The novel off-axis high-order field ion funnel transport system according to claim 1, characterized in that, The rod-shaped electrode (200) is a cylindrical rod, a semi-cylindrical rod, a hyperboloid rod, or a flat rod.

9. The novel off-axis high-order field ion funnel transport system according to claim 1, characterized in that, The number of rod electrodes (200) is set to six, eight or at least twelve.

10. A novel method for applying voltage to an off-axis high-order field ion funnel, characterized in that, The novel off-axis high-order field ion funnel transport system according to any one of claims 1-9 comprises the following steps: Radio frequency voltages with opposite phases are applied to adjacent rod electrodes (200) to form a higher-order radial confinement field; A gradually varying DC voltage is applied to the inlet section (410), transition section (420) and outlet section (430) of the open rod array ion transport channel (400) to form an axial DC gradient; A differential upward bias voltage matching the polarity of the target ion is applied between the upper rod electrode (200) and the lower rod electrode (200) in the transition section (420) to form an electric field that causes the target ion to deflect upward.

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