Accelerator mass spectrometer system taking speed selector as analyzer

Abstract

The invention relates to the technical field of mass spectrometers and accelerator mass spectrometers, in particular to an accelerator mass spectrometer system taking a speed selector as an analyzer, which comprises a sample injector, an ion source, an accelerator, a magnetic analyzer, an absorption film, a speed selector and a detector, in order to miniaturize and simplify an accelerator mass spectrum, the accelerator mass spectrometer system based on the speed selector is provided for the first time, namely, the speed selector is used for replacing an electrostatic analyser 2 and a magnetic analyser 2 at the high-energy end of an accelerator mass spectrometer; therefore, on the premise of ensuring various technical indexes of the accelerator mass spectrometer, the size of the system is reduced, the cost of the instrument is also reduced, and one speed selector is equivalent to the integration of one electrostatic analyzer and one magnetic analyzer.

Description

Technical Field

[0001] The present invention relates to the technical fields of mass spectrometers and accelerator mass spectrometers, and particularly to an accelerator mass spectrometer system using a velocity selector as an analyzer. Background Art

[0002] An accelerator mass spectrometer is a high-energy isotope mass spectrometer based on an accelerator and an ion detector, belonging to a type of isotope mass spectrometry (MS). It overcomes the limitations of molecular background and isobaric background interference existing in traditional MS, and thus has extremely high isotope abundance sensitivity.

[0003] Currently, the highest abundance sensitivity measured by traditional MS is 10 -8 while that of accelerator mass spectrometry reaches 10 -15 AMS not only has such high measurement sensitivity, but also has advantages such as small sample consumption (ng level) and short measurement time. Therefore, AMS provides a powerful testing means for the in-depth development of many disciplines such as geology, oceanography, archaeology, and environment. Figure 1 FIG. 17 is a schematic structural diagram of a traditional accelerator mass spectrometer system. The system includes 4 subsystems: an ion source and injector subsystem, an accelerator subsystem, a high-energy analyzer subsystem, and a detector subsystem. However, existing accelerator mass spectrometers are usually large in volume and require a large amount of laboratory space. Moreover, an accelerator mass spectrometer consists of multiple subsystems, including an ion source and injector subsystem, an accelerator subsystem, a high-energy analyzer subsystem, and a detector subsystem, etc. The connection and coordination between these subsystems require highly precise technical support, and the complex structure increases the failure rate and maintenance difficulty of the equipment.

[0004] Therefore, in view of the problems of large equipment volume and complex system structure in the above-mentioned existing accelerator mass spectrometer systems, an accelerator mass spectrometer system using a velocity selector as an analyzer can be designed. Summary of the Invention

[0005] In order to overcome the problems of large equipment volume and complex system structure in the existing accelerator mass spectrometer systems.

[0006] The technical solution of the present invention is: an accelerator mass spectrometer system using a velocity selector as an analyzer, including a sampler, an ion source, an accelerator, a magnetic analyzer, an absorption film, a velocity selector, and a detector;

[0007] The sampler is connected to the ion source and is used to send a gaseous sample into the gas inlet ion source for ionization;

[0008] The ion source is used to generate single-charge-state and multi-charge-state ions. The ion source includes a gas inlet and a solid inlet ion source;

[0009] The accelerator is used to increase the energy of ions;

[0010] The magnetic analyzer is used to separate ions with different M / q values;

[0011] The absorption film is used to separate 39Ar and 39K ions and eliminate the interference of 39K ions on 39Ar;

[0012] The velocity selector is used to pass the selected ion 39Ar and exclude other ions;

[0013] The detector is used to measure the energy spectrum of the detected ions and record the ion count rate and total count;

[0014] Preferably, in the first step, the injector is started to send the gaseous sample into the gas injection ion source. The ion source uses electron cyclotron resonance ionization or sputtering negative ion source technology to ionize the sample gas into single-charge state and multi-charge state ions;

[0015] In the second step, a suitable acceleration voltage is set on the accelerator, and the voltage range is 0 - 800 kV. The accelerator is started to accelerate the ionized ions to the required energy. According to the M / q value of the ions to be measured, the magnetic field strength and direction of the magnetic analyzer are adjusted to separate ions with different M / q values, such as distinguishing 40Ar9+, 40Ar10+, 39Ar9+, 39Ar10+, etc., because their M / q values are all different. The accelerated ions are sent into the magnetic analyzer, and the magnetic field deflection effect on the ions is used to separate ions with different M / q values;

[0016] In the third step, the Faraday cup is used to measure the magnitude of the beam current of each different M / q ion separated by the magnetic analyzer and record the data. The separated ions are sent into the energy absorption film. By using the different energy losses of the ions in the film, 39Ar and 39K ions are further distinguished. After 39Ar and 39K pass through the energy absorption film, although there are differences in the energies of 39Ar and 39K, some differences are very small, and the detector alone cannot completely distinguish them. The traditional method requires two instruments, an electrostatic analyzer-2 and a magnetic analyzer-2 at the high-energy end behind the absorption film. Here, we use a velocity selector to replace the two instruments, electrostatic analyzer-2 and magnetic analyzer-2. For the principle of the velocity selector, see Figure 3 ;

[0017] When the \(^{39}Ar\) and \(^{39}K\) ions after passing through the energy absorption film pass through the electrostatic analyzer, the velocity selector consists of an electrostatic analyzer with left and right electrode electrostatic deflection plates and a magnetic analyzer with upper and lower magnetic poles. Under the action of the electric field force of the left and right electrodes, the ions deflect to the left; at the same time, the ions deflect to the right under the action of the magnetic force (Lorentz force) of the upper (S pole) and lower (N pole) magnetic poles. When the electric field force and the magnetic force are equal, the selected ions \(^{39}Ar\) will pass through the center of the velocity selector, and other ions such as \(^{39}K\) and so on will be excluded due to different energies and momenta and deviate from the center.

[0018] In the fourth step, start the detector, measure and record the ion count rate and the total count, and ensure that the remaining \(^{39}Ar\) ions and extremely small amounts of \(^{39}K\) ions can be accurately distinguished and recorded.

[0019] Preferably, the system further includes a Faraday cup, and the Faraday cup is used to measure the size of each different M / q ion beam separated by the magnetic analyzer.

[0020] Preferably, the gas injection includes liquid spray injection, and the solid injection includes secondary ion injection and solid heating evaporation injection.

[0021] Preferably, the ion source adopts an electron cyclotron resonance ionization ion source and a sputtering negative ion source.

[0022] Preferably, the acceleration voltage range of the accelerator is 0 - 800 kV.

[0023] Preferably, after the \(^{39}Ar\) and \(^{39}K\) ions pass through the absorption film and the velocity selector, part of the \(^{39}K\) has been excluded, and the remaining \(^{39}Ar\) and \(^{39}K\) are distinguished by the detector again and recorded.

[0024] Preferably, the velocity selector consists of an electrostatic analyzer with left and right electrode electrostatic deflection plates and a magnetic analyzer with upper and lower magnetic poles.

[0025] Advantages of the present invention:

[0026] In order to miniaturize and simplify the accelerator mass spectrometer, the present invention first proposes an accelerator mass spectrometer system based on a velocity selector. This system uses a velocity selector to replace the two instruments, namely the electrostatic analyzer - 2 and the magnetic analyzer - 2 at the high - energy end of the accelerator mass spectrometer. Thus, on the premise of ensuring the technical indicators of the accelerator mass spectrometer, the size of the system is reduced, and the cost of the instrument is also reduced. A velocity selector is equivalent to integrating an electrostatic analyzer and a magnetic analyzer together. Description of the drawings

[0027] Figure 1 Shown is a structural schematic diagram of a traditional accelerator mass spectrometer system of the accelerator mass spectrometer system of the present invention;

[0028] Figure 2 Shown is a schematic diagram of the velocity selector-based accelerator mass spectrometry system of the accelerator mass spectrometry system of the present invention;

[0029] Figure 3 Shown is the schematic diagram of the velocity selector of the accelerator mass spectrometry system of the present invention - electrostatic analyzer;

[0030] Figure 4 Shown is the schematic diagram of the velocity selector of the accelerator mass spectrometry system of the present invention - magnetic analyzer;

[0031] Figure 5 Shown is the schematic diagram of the velocity selector of the accelerator mass spectrometry system of the present invention. Detailed implementation manners

[0032] The present invention will be further described below in conjunction with embodiments.

[0033] Please refer to Figures 1-5 , the present invention provides an embodiment: an accelerator mass spectrometry system using a velocity selector as an analyzer, including a sampler, an ion source, an accelerator, a magnetic analyzer, an absorption film, a velocity selector, and a detector;

[0034] The sampler is connected to the ion source and is used to send the gaseous sample into the gas injection ion source for ionization;

[0035] The ion source is used to generate single-charged and multi-charged ions, and the ion source includes a gas injection and a solid injection ion source;

[0036] The accelerator is used to increase the energy of the ions;

[0037] The magnetic analyzer is used to separate ions with different M / q values;

[0038] The absorption film is used to separate 39Ar and 39K ions and eliminate the interference of 39K ions on 39Ar;

[0039] The velocity selector is used to pass the selected ion 39Ar and exclude other ions;

[0040] The detector is used to measure the energy spectrum of the detected ions and record the ion count rate and total count

[0041] Preferably, the system further includes a Faraday cup, and the Faraday cup is used to measure the magnitude of each different M / q ion beam separated by the magnetic analyzer.

[0042] Preferably, the gas injection includes liquid spray injection, and the solid injection includes secondary ion injection and solid heating evaporation injection.

[0043] Preferably, the ion source adopts an electron cyclotron resonance ionization ion source and a sputtering negative ion source.

[0044] Preferably, the acceleration voltage range of the accelerator is 0 - 800 kV.

[0045] Preferably, after the 39Ar and 39K ions pass through the absorption film and the velocity selector, part of the 39K has been excluded, and the remaining 39Ar and 39K are distinguished again by the detector and recorded.

[0046] Preferably, the velocity selector consists of an electrostatic analyzer with left and right electrostatic deflection plates of electrodes, and a magnetic analyzer with upper and lower magnetic poles.

[0047] During operation, in the first step, start the injector to send the gaseous sample into the gas injection ion source. The ion source uses electron cyclotron resonance ionization or sputtering negative ion source technology to ionize the sample gas into single-charge-state and multi-charge-state ions.

[0048] In the second step, set an appropriate acceleration voltage on the accelerator, with the voltage range of 0 - 800 kV. Start the accelerator to accelerate the ionized ions to the required energy. According to the M / q value of the ions to be measured, adjust the magnetic field strength and direction of the magnetic analyzer to separate ions with different M / q values, such as distinguishing 40Ar9+, 40Ar10+, 39Ar9+, 39Ar10+, etc., because their M / q values are all different. Send the accelerated ions into the magnetic analyzer, and use the deflection effect of the magnetic field on the ions to separate ions with different M / q values.

[0049] In the third step, use the Faraday cup to measure the beam current size of each ion beam with different M / q values separated by the magnetic analyzer and record the data. Send the separated ions into the energy absorption film, and further distinguish 39Ar and 39K ions by the different energy losses of the ions in the film. After 39Ar and 39K pass through the energy absorption film, although there is a difference in energy between 39Ar and 39K, and some differences are very small, the detector alone cannot completely distinguish them. The traditional method requires two instruments, an electrostatic analyzer - 2 and a magnetic analyzer - 2 at the high-energy end behind the absorption film. Here, we use a velocity selector to replace the two instruments, electrostatic analyzer - 2 and magnetic analyzer - 2. For the principle of the velocity selector, see Figure 3 ;

[0050] When the 39Ar and 39K ions after passing through the energy absorption film pass through the electrostatic analyzer, the velocity selector consists of an electrostatic analyzer with left and right electrostatic deflection plates of electrodes and a magnetic analyzer with upper and lower magnetic poles. Under the action of the electric field forces of the left and right electrodes, the ions deflect to the left; at the same time, under the action of the magnetic forces (Lorentz forces) of the upper (S pole) and lower (N pole) magnetic poles, the ions deflect to the right. When the electric field force and the magnetic force are equal, the selected ions 39Ar will pass through the center of the velocity selector, and other ions such as 39K ions will be excluded due to different energies and momenta and deviate from the center.

[0051] In the fourth step, start the detector, measure and record the counting rate and total count of the ions, and ensure that the remaining 39Ar ions and extremely small amounts of 39K ions can be accurately distinguished and recorded.

Claims

1. An accelerator mass spectrometer system using a velocity selector as an analyzer, characterized in that: It includes an injector, an ion source, an accelerator, a magnetic analyzer, an absorption film, a speed selector and a detector; The injector is connected to the ion source and is used to send the gaseous sample into the gas injection ion source for ionization; The ion source is used to generate single-charged and multi-charged ions, and the ion source includes a gas injection ion source and a solid injection ion source; Accelerators are used to increase the energy of ions; Magnetic analyzers are used to separate ions of various M / q values; The absorption membrane is used to separate 39Ar and 39K ions and eliminate the interference of 39K ions on 39Ar; The velocity selector is used to pass the selected ion 39Ar and exclude other ions; The detector is used to measure the energy spectrum of the incoming probe ions and record the ion count rate and total count.

2. The accelerator mass spectrometer system with a velocity selector as an analyzer according to claim 1, characterized in that: The system also includes a Faraday cup for measuring the magnitude of each different M / q ion beam separated by the magnetic analyzer.

3. The accelerator mass spectrometer system with a velocity selector as an analyzer according to claim 1, characterized in that: Gas sampling includes liquid spray sampling, and solid sampling includes secondary ion sampling and solid heating evaporation sampling.

4. The accelerator mass spectrometer system with a velocity selector as an analyzer according to claim 1, characterized in that: The ion source adopts electron cyclotron resonance ionization ion source and sputtering negative ion source.

5. The accelerator mass spectrometer system with a velocity selector as an analyzer according to claim 1, characterized in that: The acceleration voltage range of the accelerator is 0~800kV.

6. The accelerator mass spectrometer system with a velocity selector as an analyzer according to claim 1, characterized in that: After 39Ar and 39K ions pass through the absorption membrane and velocity selector, part of 39K has been excluded, and the remaining 39Ar and 39K are distinguished again by the detector and recorded.

7. The accelerator mass spectrometer system with a velocity selector as an analyzer according to claim 1, characterized in that: The speed selector is composed of an electrostatic analyzer with two left and right electrode electrostatic deflection plates and a magnetic analyzer with two upper and lower magnetic poles.

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