Inorganic mass spectrometer

Abstract

Inorganic mass spectrometer, the inorganic mass spectrometer comprising: a multi-charge state ion source (1) used to generate a high-current ion beam of multiply charged states (3+ or above 3+), wherein the high-current ion beam comprises a constant particle beam, a microparticle beam, a trace particle beam and an ultra-trace particle beam, and the ultra-trace particle beam comprises an ultra-trace isotope and an ultra-trace background; a front-end analysis system (2) connected to the multi-charge state ion source (1) and used to shield the constant particle beam, the microparticle beam and the trace particle beam, to absorb and measure the constant particle beam, the microparticle beam and the trace particle beam, and to output the ultratrace particle beam; a backend analysis system (3) connected to the frontend analysis system (2) and used to eliminate the ultratrace background in the ultratrace particle beam; and an ion detector (4) connected to the backend analysis system (3) and used to receive the ultratrace isotope and to measure the ultratrace isotope, wherein the frontend analysis system (2) includes: an acceleration section (2-1) connected to the multi-charge state ion source (1) and used to accelerate the high-current ion beam; a front-end analyzer (2-2) connected to the acceleration section (2-1) and the back-end analysis system (3), respectively, and used to separate the constant particle beam, the microparticle beam, and the trace particle beam from the ultratrace particle beam and output the ultratrace particle beam to the back-end analysis system (3), wherein the front-end analyzer (2-2) is any one or a combination of any two of an electrostatic analyzer (3-1), a quadrupole analyzer, or a time-of-flight analyzer; and an ion receiver (2-3) arranged at an output end of the front-end analyzer (2-2) and used to absorb and measure the constant particle beam, the microparticle beam and the trace particle beam, wherein the backend analysis system (3) comprises an electrostatic analyzer (3-1), an energy absorption film (3-2) and a velocity filter (3-3), wherein an input end of the electrostatic analyzer (3-1) is connected to an output end of the front-end analysis system (2), wherein the energy absorption film (3-2) is fixed between an output end of the electrostatic analyzer (3-1) and an input end of the velocity filter (3-3), wherein an output end of the velocity filter (3-3) is connected to the ion detector (4), wherein the energy absorption film (3-2) is a nanoscale uniform film or a gas space, such that different isobaric heterotopes with the same energy have a different energy loss on the energy absorption film (3-2) and that different ions with the same charge-to-mass ratio have a different energy loss on the energy absorption film (3-2) after the ions have passed through the energy absorption film (3-2).

Description

Technical field

[0001] The present invention relates to the field of mass spectrometry instruments and, more particularly, to an inorganic mass spectrometer. background

[0002] The existing inorganic mass spectrometer consists of an ion source system, an analysis system (mainly including an electrostatic analyzer, a time-of-flight analyzer, a quadrupole analyzer, and the like), and an ion detector system. During measurement, the sensitivity of the inorganic mass spectrometer is affected due to the interference of the molecular ion background and the isobaric heterotopic ion background, and the lower detection limit can be in the range of 10 -12 g / g and reach a trace analysis range. The measurement accuracy is up to 0.5%.

[0003] Due to the advancement of materials science, nuclear energy, environmental science, geology, biomedicine, archaeology, oceanography, and the like, the measurement sensitivity and accuracy of elements must also be improved. The lower detection limit is set at 10 -12 g / g per 10 -13 -10 -17 g / g, i.e., down to the ultratrace range. The requirements for measurement accuracy have increased from 0.5% to less than 0.1%. Currently, the measurement sensitivity and accuracy of the inorganic mass spectrometer are far from meeting the measurement requirements.

[0004] CN 108 987 242 A discloses an isotope mass spectrometer. The mass spectrometer comprises an electron cyclotron resonance ion source, a front analyzer, a rear analyzer, and an ion detector. An electron cyclotron resonance ion source is connected to a front analyzer, and the electron cyclotron resonance ion source is used to generate an ion beam with a multivalent charge state. The front analyzer is connected to the rear analyzer. The front analyzer selects and separates the ion beams and receives the ion beams of constant, trace, and ultratrace concentration. The rear analyzer is connected to an ion detector, and the rear analyzer is used to remove the background of the isotopes to be detected in the ultratrace range.The ion detector is used to receive the ion beam in the ultratrace range, and the energy of the ion beam in the ultratrace range is measured and separated to obtain the ultratrace isotope. The mass spectrometer of the invention has the advantages of eliminating the molecular background and the isobaric background, as well as the advantages of strong ion current and high transmission efficiency, effectively improving the abundance sensitivity of isotope MS measurement.

[0005] US 2017 / 0154760 A1 discloses a method for treating a particle beam, which is particularly suitable for mass spectrometry of 14C is of interest. A particle beam containing positive ions is passed through a charge exchange cell containing a target gas. The target gas is electrically insulating at room temperature and pressure. At least a portion of the positive ions of the particle beam are converted into negative ions by interaction with the target gas. The particle beam impinging on the charge exchange cell contains molecules and / or molecular ions that interact with the target gas to reduce the concentration of molecules as a result of repeated collisions with particles of the target gas. A corresponding mass spectrometry system is also disclosed.

[0006] US 6 455 844 B1 discloses a method for performing accelerator mass spectrometry, comprising generating a beam of positive ions with different multiple charges from a multiply charged ion source; selecting positive ions with a charge state of +2 to +4 to define a portion of the beam of positive ions; and scattering at least a portion of this partial beam of positive ions at the surface of a target to convert a portion of the positive ions directly into negative ions.

[0007] US 2013 / 0112869 A1 discloses a mass spectrometry system based on the general principle of accelerator mass spectrometry. An ion source generates a beam of ions with a negative charge state. A first mass analyzer allows only ions with a specified mass to pass through. The ions are passed through a stripper target containing helium and / or hydrogen as a stripping gas to change the charge state of the ions from negative to positive and to dissociate molecular ions through collisions. A second mass analyzer allows ions in the 1+ charge state with the specified mass to pass through, which are detected by a detector. By using helium and / or hydrogen gas and detecting ions in the 1+ charge state, it becomes possible to use kinetic energies below 200 keV without excessive transmission losses due to angular scattering.At sufficiently low energies, no additional acceleration is required after ion extraction from the ion source. In alternative embodiments, no mass selection is performed prior to charge exchange. SUMMARY

[0008] An object of the present invention is to provide an inorganic mass spectrometer to improve the measurement sensitivity and accuracy of the inorganic mass spectrometer.

[0009] To achieve the above-mentioned purpose, the present invention provides the following technical solution.

[0010] An inorganic mass spectrometer includes: a multi-charge state ion source used to generate a high-current ion beam of multiply charged states (3+ or above 3+), the high-current ion beam comprising a constant particle beam, a microparticle beam, a trace particle beam, and comprises an ultratrace particle beam and the ultratrace particle beam comprises an ultratrace isotope and an ultratrace background; a front-end analysis system connected to the multi-charge state ion source and used to shield the constant particle beam, the microparticle beam, and the trace particle beam, absorb and measure the constant particle beam, the microparticle beam, and the trace particle beam, and output the ultratrace particle beam; a backend analysis system connected to the frontend analysis system and used to eliminate the ultratrace background in the ultratrace particle beam; and an ion detector connected to the backend analysis system and used to receive the ultratrace isotope and measure the ultratrace isotope.

[0011] The front-end analysis system includes an acceleration section connected to the multi-charge state ion source and used to accelerate the high-current ion beam; a front-end analyzer connected to each of the acceleration section and the back-end analysis system and used to separate the constant particle beam, the microparticle beam, and the trace particle beam from the ultra-trace particle beam and output the ultra-trace particle beam to the back-end analysis system, wherein the front-end analyzer is any one or a combination of any two of an electrostatic analyzer, a quadrupole analyzer, or a time-of-flight analyzer; and an ion receiver disposed at an output end of the front-end analyzer and used to absorb and measure the constant particle beam, the microparticle beam, and the trace particle beam.wherein the backend analysis system comprises an electrostatic analyzer, an energy absorption film, and a velocity filter, wherein an input end of the electrostatic analyzer is connected to an output end of the frontend analysis system, wherein the energy absorption film is secured between an output end of the electrostatic analyzer and an input end of the velocity filter, wherein an output end of the velocity filter is connected to the ion detector, wherein the energy absorption film is a nanoscale uniform film or a gas space such that different isobaric heterotopes with the same energy exhibit a different energy loss on the energy absorption film, and that different ions with the same charge-to-mass ratio exhibit a different energy loss on the energy absorption film after the ions have passed through the energy absorption film.

[0012] Optionally, the multi-charge state ion source is an electron cyclotron resonance ion source and can generate high-current ion beams of multiply charged states (3+ and above 3+) for all elements from H to Pu, actinide elements and transactinide elements.

[0013] Optionally, the acceleration section is a high-current single-stage electrostatic acceleration tube, and the acceleration tube has a beam intensity in a range of 0.1 µA - 5000 µA and an operating voltage of 10 kV - 400 kV.

[0014] Optionally, the ion receiver is a set of Faraday cups.

[0015] Optionally, the ion detector is a solid detector or a gas detector.

[0016] According to specific embodiments provided in the present invention, the present invention discloses the following technical effects: First, the measurement sensitivity is improved. The inorganic mass spectrometer of the present invention uses a multi-charge state ion source, generates no interference from the molecular background, and significantly improves the measurement sensitivity. The lower detection limit can be in the range of 10 -13 -10 -17 g / g, be what 10 7 -10 5 -times lower than the 10 -12 g / g of the conventional inorganic mass spectrometer. The element content measured with the conventional inorganic mass spectrometer belongs to the microtrace range. The measurement range of the inorganic mass spectrometer based on the multi-charge state ion source of the present invention belongs to the ultratrace range.

[0017] Second, the measurement accuracy is improved. The inorganic mass spectrometer of the present invention uses a multi-charge state ion source with a beam area of ​​102 -10 3 µA. For the measurement of trace and ultratrace elements, the transmission efficiency can reach more than 30%. This is 10-100 times higher than the beam intensity and count rate of conventional inorganic high-precision mass spectrometers. Therefore, the measurement accuracy is significantly improved, and the measurement accuracy can be achieved for trace elements (10 -9 g / g) better than 0.1%.

[0018] Third, the ability to eliminate various backgrounds is improved. Due to the use of multiple charge states, the energy of the ions is improved (the energy of the ions is equal to the product of the number of charges and the accelerating voltage). After improving the energy, it is advantageous to eliminate the interference of the isobaric heterotopic backgrounds, which is useful for reducing the interference of the scattering background and improving the energy fraction of the detector, thereby improving the measurement sensitivity.

[0019] Fourth, the sample dosage is reduced. The multi-charge-state ion source used has a strong beam, and the beam is strong because the ionization efficiency of the sample is high. Therefore, the sample dosage is low to achieve the same measurement and statistical accuracy. Short description of the drawing

[0020] To more clearly describe the technical solutions in the embodiments of the present invention or in the prior art, the accompanying drawings necessary for describing the embodiments are briefly presented below. The accompanying drawings in the following description obviously show only some embodiments of the present invention, and a person of ordinary skill in the art can derive other drawings from these accompanying drawings without creative effort. Fig. 1 is a schematic structural diagram of an inorganic mass spectrometer of the present invention. Description of reference numbers:

[0021] 1 represents a multi-charge state ion source, 2 represents a front-end analysis system, 2-1 represents an acceleration section, 2-2 represents a front-end analyzer, 2-3 represents an ion receiver, 3 represents a back-end analysis system, 3-1 represents an electrostatic analyzer, 3-2 represents an energy absorption film, 3-3 represents a velocity filter, and 4 represents an ion detector. Detailed description

[0022] Below, the technical solutions in the embodiments of the present invention are clearly and completely described with reference to the accompanying drawings. It goes without saying that the described embodiments are only some, and not all, of the embodiments of the present invention. All other embodiments obtained based on the embodiments of the present invention by a person of ordinary skill in the art without creative effort fall within the scope of the present disclosure.

[0023] There are three main factors that affect the measurement sensitivity and accuracy of an inorganic mass spectrometer: the first is the level of molecular background and isobaric heterotopic background; the second is the ion transmission efficiency; and the third is the beam intensity of the ion source. Among these three factors, the level of molecular background and isobaric heterotopic background is the most important factor affecting sensitivity, while the transmission efficiency and beam intensity of the ion source are the main factors affecting accuracy.

[0024] In order to improve the measurement sensitivity and accuracy, the present invention investigates the main problems affecting the measurement sensitivity and accuracy of the inorganic mass spectrometer, that is, the problems of molecular background and isobaric heterotopic background, problems of ion transfer efficiency and ion source beam intensity: An inorganic mass spectrometer based on a multi-charge state ion source MCI-MS (Multi-Charge State Ion Source) was firstly proposed.

[0025] In order to make the above object, features and advantages of the present invention more clear and understandable, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. Embodiment

[0026] As in Fig.As shown in Figure 1, the inorganic mass spectrometer of the present invention includes a multi-charge state ion source 1, a front-end analysis system 2, a back-end analysis system 3, and an ion detector 4.

[0027] The multi-charge state ion source 1 is connected to the front-end analysis system 2; the front-end analysis system 2 is connected to the back-end analysis system 3; and the back-end analysis system 3 is connected to the ion detector 4.

[0028] The multi-charge state ion source 1 is used to generate high-current ion beams of multiply charged states such as 3+, 4+, and the like. The high-current ion beam includes a constant particle beam, a microparticle beam, a trace particle beam, and an ultratrace particle beam. The ultratrace particle beam includes an ultratrace isotope and an ultratrace background.

[0029] For example, for CO2 ions such as C + , C2+ , C 3+ , C 4+ , C 5+ , C 6+ and the like. C 2+ and C + represent a doubly charged or singly charged state, C 3+ , C 4+ and C 5+ are multiply charged states (multiple charge states) and C 6+ is a highly charged state or an electronless state.

[0030] Currently, there are two main types of ion sources capable of extracting the multiple charge state; one is an electron cyclotron resonance (ECR) ion source and the other is a radio frequency (RF) spark discharge (HF) ion source.

[0031] In this application, the multiple charge state ion source is an electron cyclotron resonance ion source capable of generating high-current ion beams of multiply charged states such as 3+, 4+, or the like for all elements from H to Pu, actinide elements, and transactinide elements. Due to the high production efficiency of the multiple charge state and good beam quality, the ECR ion source is currently the preferred ion source for MCI-MS. The microwave frequency of the ion source is in the range of 5 GHz to 25 GHz. The microwave frequency in this range is the optimal frequency for generating multiple charge states. Furthermore, the ECR ion source is based on gas injection, which reduces many sample preparation processes and reduces the pollution caused by the sample preparation processes.

[0032] The front-end analysis system 2 is used to select and separate the high-current ion beam, shield the constant particle beam, the microparticle beam, and the trace particle beam, absorb and measure the constant particle beam, the microparticle beam, and the trace particle beam, and output the ultratrace particle beam.

[0033] The front-end analysis system 2 includes: an acceleration section 2-1 connected to the multi-charge state ion source 1 and used to accelerate the high-current ion beam; a front-end analyzer 2-2 connected to the acceleration section 2-1 and the back-end analysis system 3, respectively, and used to separate the constant particle beam, the microparticle beam, and the trace particle beam from the ultratrace particle beam and output the ultratrace particle beam to the back-end analysis system 3; and an ion receiver 2-3 arranged at an output end of the front-end analyzer 2-2 and used to absorb and measure the constant particle beam, the microparticle beam, and the trace particle beam.

[0034] In this embodiment, the acceleration section 2-1 has no gas or solid scraper component and is a high-current, single-stage electrostatic acceleration tube. The acceleration tube has a beam intensity in the range of 0.1 µA–5000 µA and an operating voltage of 10 kV–400 kV to increase the energy of the ions so that the ions pass through the front-end analyzer 2-2 to obtain good mass resolution.

[0035] The front-end analyzer is any one of a magnetic analyzer, an electrostatic analyzer, a quadrupole analyzer, or a time-of-flight analyzer, or may be a combination of any two of the above four analyzers.

[0036] The ion receiver 2-3 is a set of movable Faraday cups, usually 3-7 Faraday cups, and the position of each Faraday cup can be changed.

[0037] The backend analysis system 3 is used to remove the interference of the ultratrace background in the ultratrace particle beam in order to detect the ultratrace elements (10 -13 -10 -17 g / g); the ultratrace background contains isobaric heterotopic ions and ions with the same charge-to-mass ratio as the ultratrace isotope. For example, radioactive 14C impurities in materials are measured and 14C 4+-ions are selected; there is interference from the isobaric heterotope 14N 4+ and there is also an interference of ions with the same charge-to-mass ratio (e.g. 7Li 2+ , 21Ne 6+ and the like). The device is capable of effectively removing these ultra-trace substrates.

[0038] The backend analysis system 3 includes an electrostatic analyzer 3-1, an energy absorption film 3-2 and a velocity filter 3-3.

[0039] An input end of the electrostatic analyzer 3-1 is connected to an output end of the front-end analysis system 2, and the energy absorption film 3-2 is fixed between an output end of the electrostatic analyzer 3-1 and an input end of the velocity filter 3-3; and an output end of the velocity filter 3-3 is connected to the ion detector 4.

[0040] The velocity filter 3-3 can be replaced by a magnetic analyzer and a second electrostatic analyzer, and then the back-end analysis system 3 specifically includes: a first electrostatic analyzer, an energy absorption film, a magnetic analyzer, and a second electrostatic analyzer. An input end of the first electrostatic analyzer is connected to an output end of the front-end analysis system 2, and the energy absorption film is fixed between an output end of the first electrostatic analyzer and an input end of the magnetic analyzer; and an output end of the magnetic analyzer is connected to an input end of the second electrostatic analyzer, and an output end of the second electrostatic analyzer is connected to the ion detector.

[0041] The energy absorption film 3-2 is a nanoscale uniform film or a gas space. After ions have passed through the energy absorption film 3-2 (or the gas), first, the isobaric heterotope (e.g., 14C 4+ and 14N 4+ ) with the same energy have a different energy loss in the film (or gas); and secondly, ions with the same charge-to-mass ratio (e.g., 14C 4+ , 7Li 2+ , 21Ne 6+ , 28Si 8+ or the like) exhibit a large difference in energy loss in the film (or gas). Both of the above cases can be identified and eliminated by the electrostatic analyzer, the magnetic analyzer, or the velocity filter of the backend analyzer.

[0042] Ion detector 4 is a solid detector or a gas detector. The solid detector is a thin-window (10 nm - 50 nm) or windowless solid detector, and the gas detector is a thin-window (30 nm - 50 nm, SiN materials).

[0043] The ion detector 4 of this application includes a solid-state detector or a gas detector with high energy resolution, an electron sink, and data acquisition components. After the ultratrace particle beams pass through the backend analyzer, the interference from isobaric heterotopic ions and ions with the same charge-to-mass ratio as the ultratrace isotope cannot be completely eliminated. Due to the characteristic that the energy of these interfering ions is obviously different from that of the ultratrace isotope, the measurement performed by the high energy and charge resolution detector can further identify and eliminate the background interference.

[0044] The inorganic mass spectrometer is a multi-charge-state ion source-based inorganic mass spectrometer. Its specific structure includes a multi-charge-state ion source, a front-end analysis system 2, a back-end analysis system 3, and an ion detector. The multi-charge-state ion source is connected to the front-end analysis system 2; the front-end analysis system 2 is connected to the back-end analysis system 3; and the back-end analysis system 3 is connected to the ion detector. The instrument has the ability to eliminate the molecular background and reduce the isobaric heterotopic background, and also has the advantages of a strong beam, high transmission efficiency, and the like. The measurement sensitivity and accuracy of the inorganic mass spectrometer are significantly improved.

[0045] The individual embodiments of the present specification are described in a progressive manner, the individual embodiments focus on the difference from other embodiments, and the same and similar parts among the embodiments may refer to each other.

[0046] Several examples are used to illustrate the principles and methods of implementing the present invention. The description of the embodiments is intended to illustrate the method and basic principles of the present invention. Furthermore, those skilled in the art may make various modifications to the specific embodiments and scope of application in accordance with the teachings of the present invention. Accordingly, the contents of this description should not be construed as limiting the invention.

Claims

[1] Inorganic mass spectrometer, wherein the inorganic mass spectrometer comprises: a multi-charge state ion source (1) used to generate a high-current ion beam of multiply charged states (3+ or above 3+), wherein the high-current ion beam comprises a constant particle beam, a microparticle beam, a trace particle beam and an ultra-trace particle beam, and the ultra-trace particle beam comprises an ultra-trace isotope and an ultra-trace background; a front-end analysis system (2) connected to the multi-charge state ion source (1) and used to shield the constant particle beam, the microparticle beam and the trace particle beam, to absorb and measure the constant particle beam, the microparticle beam and the trace particle beam, and to output the ultratrace particle beam; a backend analysis system (3) connected to the frontend analysis system (2) and used to eliminate the ultratrace background in the ultratrace particle beam; and an ion detector (4) connected to the backend analysis system (3) and used to receive the ultratrace isotope and to measure the ultratrace isotope, wherein the frontend analysis system (2) includes: an acceleration section (2-1) connected to the multi-charge state ion source (1) and used to accelerate the high-current ion beam; a front-end analyzer (2-2) connected to the acceleration section (2-1) and the back-end analysis system (3), respectively, and used to separate the constant particle beam, the microparticle beam, and the trace particle beam from the ultratrace particle beam and output the ultratrace particle beam to the back-end analysis system (3), wherein the front-end analyzer (2-2) is any one or a combination of any two of an electrostatic analyzer (3-1), a quadrupole analyzer, or a time-of-flight analyzer; and an ion receiver (2-3) arranged at an output end of the front-end analyzer (2-2) and used to absorb and measure the constant particle beam, the microparticle beam and the trace particle beam, wherein the backend analysis system (3) comprises an electrostatic analyzer (3-1), an energy absorption film (3-2) and a velocity filter (3-3), wherein an input end of the electrostatic analyzer (3-1) is connected to an output end of the front-end analysis system (2), wherein the energy absorption film (3-2) is fixed between an output end of the electrostatic analyzer (3-1) and an input end of the velocity filter (3-3), wherein an output end of the velocity filter (3-3) is connected to the ion detector (4), wherein the energy absorption film (3-2) is a nanoscale uniform film or a gas space, such that different isobaric heterotopes with the same energy have a different energy loss on the energy absorption film (3-2) and that different ions with the same charge-to-mass ratio have a different energy loss on the energy absorption film (3-2) after the ions have passed through the energy absorption film (3-2). [2] An inorganic mass spectrometer according to claim 1, wherein the multi-charge state ion source (1) is an electron cyclotron resonance ion source and is capable of generating a high-current ion beam of multiply charged states (3+ and above 3+) for all elements from H to Pu, actinide elements and transactinide elements. [3] The inorganic mass spectrometer according to claim 1, wherein the accelerating section (2-1) is a high-current single-stage electrostatic accelerating tube, and the accelerating tube has a beam intensity in a range of 0.1 µA - 5000 µA and an operating voltage of 10 kV - 400 kV. [4] An inorganic mass spectrometer according to claim 1, wherein the ion receiver (2-3) is a set of Faraday cups. [5] An inorganic mass spectrometer according to claim 1, wherein the ion detector (4) is a solid detector or a gas detector.

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