CN116399661B

CN116399661B - Femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region in-situ analysis system and method

Info

Publication number: CN116399661B
Application number: CN202310332602.6A
Authority: CN
Inventors: 李延河; 范昌福; 胡斌; 郭东伟
Original assignee: Institute of Mineral Resources of Chinese Academy of Geological Sciences
Current assignee: Institute of Mineral Resources of Chinese Academy of Geological Sciences
Priority date: 2023-03-31
Filing date: 2023-03-31
Publication date: 2023-11-24
Anticipated expiration: 2043-03-31
Also published as: CN116399661A

Abstract

The application relates to a femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region in-situ analysis system and method, wherein femto-second ultraviolet laser is used for ablating sulfide aerosol particles of a sample to be detected in a closed environment; carrying the sulfide aerosol particles into SF in a closed environment by helium carrier gas ₆ In the gas preparation device, brF diluted with helium ₅ The gas reacts to obtain SF-containing gas ₆ A mixture of gases; removing the SF-containing ₆ Impurity gas in the mixed gas of the gases to obtain pure target SF ₆ Gas, purifying the target SF ₆ And (5) feeding the gas into a gas isotope ratio mass spectrometer for testing to obtain a test result of the tetrasulfur isotope composition. The application samples and fluorinates the micro-area in situ erosion of the traditional laser probe and SF ₆ The preparation is carried out simultaneously in situ, changed into different places and is finished successively, thereby avoiding infrared laser ablation-SF ₆ Fractionation and effects resulting from incomplete reactions and reaction of the fluorinating agent with the matrix component during the preparation process.

Description

Femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region in-situ analysis system and method

Technical Field

The application belongs to the technical field of sulfide tetrasulfur isotope analysis, and particularly relates to a femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-area in-situ analysis system and method.

Background

Internationally, conventional laser probe-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in situ determination (SF) ₆ The basic principle of the method) is as follows: focusing the laser beam on a micro-area of the sample surface, at F ₂ /BrF ₅ In atmosphere, using laser beamRapidly heating the sample, and heating and melting sulfide, gasifying sulfide and reacting with fluorinating agent to form SF ₆ And (3) gas. SF (sulfur hexafluoride) ₆ After the gas is purified and separated by gas chromatography, the gas enters a gas isotope mass spectrometer sample injection system to determine the sulfur isotope composition.

However, the conventional laser probe-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region in-situ analysis technology has some unresolved problems due to design defects: (1) The low temperature partial fluorination reaction is incomplete due to the temperature gradient and boundary effect of laser heating, resulting in significant fractionation. (2) F in the laser heating process ₂ /BrF ₅ The fluorinating agent reacts with minerals in the laser heating area and also reacts with components outside the heating area, so that the generated impurity gas causes background rise and influences the accuracy of analysis results. (3) In order to prevent the fluorinating agent from reacting with other easily fluoridated mineral particles in the fluorination process and reduce the background, many laboratories take measures such as prefluorination. Not only does the pretreatment add much additional effort, but in practice it is still difficult to completely eliminate the effect of the reaction of the fluorinating agent with the matrix components.

Disclosure of Invention

In view of the above analysis, the present invention aims to provide a system and a method for in-situ analysis of a femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region, that is, a system and a method for in-situ analysis of a femto-second laser probe sulfide tetrasulfur isotope micro-region, which are used for solving the above problems in the prior art.

The purpose of the invention is realized in the following way:

on the one hand, a femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in-situ analysis system is provided, which comprises the following steps:

a femtosecond ultraviolet laser ablation device configured to ablate sulfide aerosol particles from a sample to be tested;

SF ₆ a gas preparation device connected with the gas outlet of the femtosecond ultraviolet laser ablation device and configured to contain sulfide aerosol particles and provide a reaction space, sulfideAerosol particles and BrF ₅ The gas reacts in the reaction space to generate SF containing target ₆ A mixture of gases;

SF ₆ enrichment and purification device and SF ₆ The gas outlet of the gas preparation device is connected and configured to collect target SF in the purified mixed gas ₆ A gas;

gas isotope ratio mass spectrometer, gas isotope ratio mass spectrometer and SF through shunt valve subassembly ₆ The enrichment and purification device is connected and used for measuring the target SF ₆ Polysulfide isotope composition of gas.

Further, the femtosecond ultraviolet laser ablation device is provided with a femtosecond laser, a laser ablation platform and a first helium gas source; a sample pool for containing a sample to be tested is arranged in the laser ablation platform, and the femtosecond laser is configured to emit femtosecond ultraviolet laser to the surface of the sample to be tested in the sample pool so as to ablate sulfide aerosol particles from the sample to be tested; the first helium source is configured to provide a helium carrier gas to blow out ablated sulfide aerosol particles from the sample cell.

Further, SF ₆ The gas preparation device comprises a micro nickel fluorination reactor and a BrF ₅ A gas cylinder and a second helium source;

BrF ₅ the gas cylinder is connected with a micro nickel fluorination reactor for providing BrF needed by the reaction ₅ A gas;

second helium source and BrF ₅ A cylinder connection configured to provide helium to dilute BrF fed to the micro nickel fluorination reactor ₅ A gas;

sulfide aerosol particles and BrF ₅ The gas reacts in the mini nickel fluorination reactor to generate SF containing target ₆ A mixture of gases.

Further, brF ₅ The gas outlet of the gas storage bottle is connected with a stainless steel capillary tube, the stainless steel capillary tube is connected with the inlet of the miniature nickel fluorination reactor through a three-way valve, and the inner diameter of the stainless steel capillary tube is 0.13mm and the length of the stainless steel capillary tube is 10m.

Further, the micro nickel fluorination reactor comprises a pure nickel tube, the outer diameter of the pure nickel tube is 6.4mm, the inner diameter of the pure nickel tube is 3.0mm, and the length of the pure nickel tube is 400mm;

the inside of the pure nickel pipe comprises a first space and a second space, the first space is a temporary storage space for feeding aerosol particles, the second space is communicated with the outlet of the pure nickel pipe, and the second space is filled with CoF ₃ Powder and Ni powder, and Ni powder is closer to the outlet of the pure nickel tube.

Further, SF ₆ The gas preparation device also comprises a first cold trap which is arranged at the gas outlet of the micro nickel fluorination reactor and SF ₆ The air inlets of the enrichment and purification device are arranged between the air inlets;

SF ₆ the enrichment and purification device comprises a first enrichment and purification assembly, a second enrichment and purification assembly and a gas chromatographic column, wherein the gas chromatographic column is arranged between the first enrichment and purification assembly and the second enrichment and purification assembly;

the first enrichment purification assembly has a first six-way valve and a second cold trap, and the second enrichment purification assembly has a second six-way valve and a third cold trap.

Further, the diverter valve assembly comprises a micro valve and a fourth cold trap, a valve port I of the micro valve is connected with an air outlet of the second enrichment and purification assembly, a valve port II of the micro valve is connected with an inlet of the fourth cold trap, and an outlet of the fourth cold trap is connected with a gas isotope mass spectrum; the third valve port of the micro valve is a waste gas outlet communicated with the atmosphere.

Further, at least one of the first cold trap, the second cold trap, the third cold trap and the fourth cold trap is a temperature-adjustable liquid nitrogen cold trap;

the liquid nitrogen cold trap with adjustable temperature comprises:

a liquid nitrogen container filled with liquid nitrogen;

the cylinder body is provided with an opening at one end and a closing at the other end, the opening end of the cylinder body is positioned below the liquid nitrogen level of the liquid nitrogen container, and the closing end of the cylinder body is positioned above the liquid nitrogen level; the closed end of the cylinder body is provided with an exhaust valve, and the inner space of the cylinder body is communicated with the outside atmosphere through the exhaust valve;

the U-shaped enrichment pipe is provided with an air inlet and an air outlet, a U-shaped enrichment section is arranged between the air inlet and the air outlet, the U-shaped enrichment section passes through the closed end of the cylinder and is arranged in the inner space of the cylinder, at least one part of the U-shaped enrichment section can be positioned in liquid nitrogen, the air inlet and the air outlet are positioned outside the cylinder, the air inlet is used for inflow of mixed gas containing target gas, and the air outlet is used for outflow of impurity gas in the freezing process and target gas after freezing enrichment purification; a heating wire is wound on the U-shaped enrichment section; the U-shaped enrichment section is also provided with a thermocouple for monitoring the temperature of the U-shaped enrichment section;

and the temperature controller is electrically connected with the heating wire and the thermocouple and can control the heating temperature and time of the heating wire according to the temperature information monitored by the thermocouple.

On the other hand, the invention also provides a femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region in-situ analysis method, which uses the femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region in-situ analysis system; the analysis method comprises the following steps:

using femtosecond ultraviolet laser to degrade sulfide aerosol particles of a sample to be tested in a closed environment;

carrying sulfide aerosol particles into SF in a closed environment using helium carrier gas ₆ In the gas preparation device, brF diluted with helium ₅ The fluorinating agent reacts to obtain SF-containing product ₆ A mixture of gases;

removal of SF-containing ₆ Impurity gas in the mixed gas of the gases to obtain pure target SF ₆ Gas, target SF to be purified ₆ And (5) feeding the gas into a gas isotope ratio mass spectrometer for testing to obtain the tetrasulfur isotope composition.

Further, the flow rate of helium carrier gas was 150ml/min.

Further, helium diluted BrF ₅ The gas is supplied into SF through a stainless steel capillary tube at a flow rate of 0.01ml/min ₆ In a gas production apparatus.

Further, a pure target SF is obtained ₆ Gas, target SF to be purified ₆ The gas is supplied into a gas isotope ratio mass spectrometer for testing, comprising the following steps:

Helium carrier gas carrying SF ₆ The mixed gas of the gases passes through a first cold trap at the temperature of 160 ℃ below zero to obtain primary puritySF ₆ A gas;

primary pure SF ₆ The gas enters a second cold trap at the temperature of minus 196 ℃ and SF ₆ The gas is frozen in a second cold trap, primary pure SF ₆ Impurity gas in the gas is discharged from an exhaust gas outlet of the first six-way valve; regulating the temperature of the second cold trap to-130 ℃, simultaneously switching the first six-way valve, and utilizing 20ml/min of the first-way back-flushing helium flow to release SF in the second cold trap ₆ The gas is carried and injected into a gas chromatographic column to obtain secondary pure SF ₆ A gas;

secondary pure SF ₆ SF after passing the gas through the gas chromatographic column ₆ The gas is frozen in a third cold trap at the temperature of minus 196 ℃, a second six-way valve is switched, the temperature of the third cold trap is regulated to minus 180 ℃, and SF is frozen ₆ The gas releases non-freezing impurity gas; regulating the temperature of the third cold trap to-130 ℃, and releasing SF in the third cold trap ₆ The gas is pure target SF ₆ A gas;

the second back-flushing helium flow of 3ml/min is used for purifying the target SF ₆ The gas is carried out, enriched in a fourth cold trap at the temperature of minus 196 ℃ through a diverter valve component, and thawed and enters a gas isotope ratio mass spectrometer.

Compared with the prior art, the femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-area in-situ analysis system and method provided by the invention can at least realize one of the following beneficial effects:

a) The invention samples and fluorinates the micro-area in situ erosion of the traditional laser probe and SF ₆ The preparation is carried out simultaneously in situ, changed into different places and is finished successively, thereby avoiding infrared laser ablation-SF ₆ Fractionation and effects resulting from incomplete reactions and reaction of the fluorinating agent with the matrix component during the preparation process.

b) Aiming at fractionation generated in the process of infrared laser heating and ablation, a femtosecond ultraviolet laser ablation sample with no obvious heat effect and small matrix effect is adopted, elements and isotopes are small in fractionation in the ablation process, aerosol particles generated by ablation are uniform in size and high in transmission efficiency, fractionation in the laser ablation and transmission process is avoided and reduced, the chemical characteristics of the sample can be truly represented, and therefore the sample does not need to be strictly matched with a standard sample, and compared with nanosecond laser, the sample has higher sensitivity and accuracy, so that the application range of the femtosecond ultraviolet laser is greatly widened.

c) With SO ₂ Compared with the method, the invention adopts SF ₆ The method has the advantages that: SF (sulfur hexafluoride) ₆ Viscosity of (C) is less than SO ₂ The memory effect of gas in pipeline transportation can be reduced, the ionization rate in a mass spectrum ion source is high, and the sensitivity is high; fluorine (F) is a monoisotopic element, and is not interfered by homoisobaric element, so that data correction is not needed, the result is more accurate, and the method is a classical method for developing sulfur isotope non-quality fractionation research.

d) The liquid nitrogen cold trap with adjustable temperature is designed for triple freezing space, the temperature of the cold trap can be adjusted, the whole process can be automatically controlled, the temperature adjustment precision is controllable, the purification and separation of target gas and impurity gas are purer, and the analysis precision is higher.

Drawings

In order to more clearly illustrate the embodiments of the present description or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the embodiments of the present description, and other drawings may be obtained according to these drawings for a person having ordinary skill in the art.

FIG. 1 is a schematic diagram of the structure of the femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in situ analysis system in example 1;

FIG. 2 is a schematic diagram of a second embodiment of the system for in situ analysis of a femto-second UV laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in example 1;

FIG. 3 is a schematic diagram showing two states of the "Load" mode and the "object" mode of the six-way valve in example 1;

FIG. 4 shows SF in example 1 ₆ A schematic structural diagram of the gas preparation device;

FIG. 5 is a schematic structural view of the diverter valve assembly in embodiment 1;

FIG. 6 is a schematic diagram of the structure of a first temperature-adjustable liquid nitrogen cold trap in example 2;

FIG. 7 is a schematic diagram of a second temperature-adjustable liquid nitrogen cold trap in example 2;

FIG. 8 is a schematic diagram of a prior art dual chamber sample cell;

FIG. 9 is a schematic diagram showing the oval sample cell in example 3 in a disassembled state;

FIG. 10 is a schematic view showing the mounting of the target holder of the elliptical sample cell of example 3 in the base;

FIG. 11 is a schematic diagram of a dual-chamber sample cell in example 3;

FIG. 12 is a schematic diagram of the structure of a second cell of the dual-chamber cell of example 3;

FIG. 13 is a schematic view showing the structure of the base of the second cuvette in example 3.

Reference numerals:

1. an existing sample cell I; 2. an existing sample cell II; 21. an argon inlet pipeline; 22. an air outlet pipeline;

100. a femtosecond ultraviolet laser ablation device; 101. a femtosecond laser; 102. an elliptical sample cell; 1021. an air intake passage; 1022. an air outlet channel I; 1023. a first base; 1024. a chamber; 1025. a first top cover; 1026. MgF (MgF) ₂ A first glass; 1027. a first target frame; 1028. a seal ring; 1029. a groove; 1030. testing the point positions; 103. a laser ablation platform; 104. a camera; 105. a first sample cell; 1051. helium carrying gas circuit; 1052. a second harrow frame; 106. a second sample cell; 1061. an air outlet channel II; 1061a, a channel inlet; 1061b, a channel outlet; 1062. a second base; 1063. a cylindrical chamber; 1064. a second top cover; 1065. MgF (MgF) ₂ A second glass; 1067. a third seal ring; 1068. a fourth seal ring; 1069. a Teflon tube; 107. a first helium source;

200、SF ₆ a gas preparation device; 201. a mini nickel fluorination reactor; 2011. a pure nickel tube; 2012. CoF (CoF) ₃ Powder; 2013. ni powder; 202. BrF (BrF) ₅ A gas cylinder; 203. a first cold trap; 204. a second helium source; 205. a three-way valve; 206. a valve exhaust port;

300、SF ₆ enrichment and purification device; 301. a first six-way valve; 302. a second cold trap; 303. a second six-way valve; 304. a third cold trap; 305. a gas chromatographic column; 306. a first back-flushing helium flow; 307. a second back-flushing helium flow; 308. a first temperature-adjustable liquid nitrogen cold trap; 3081. a liquid nitrogen barrel; 3082. an outer tube; 3082a, nitrogen inlet; 3082b, nitrogen outlet; 3083. an inner tube; 3083a, an air inlet; 3083b, air outlet; 3084. sealing the space; 3085. an air supply pipe; 309. a second type of temperature-adjustable liquid nitrogen cold trap; 3091. a liquid nitrogen container; 3092. a cylinder; 3093. an exhaust valve; 3094. a U-shaped enrichment tube; 3095. a heating wire; 3096. a thermocouple; 3097. a temperature controller;

400. a diverter valve assembly; 401. a micro valve; 402. a fourth cold trap; 403. exhaust ports;

500. a gas isotope ratio mass spectrometer;

600. And the double-path sample injection system.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

For the purpose of facilitating an understanding of the embodiments of the present application, reference will now be made to the following description of specific embodiments, taken in conjunction with the accompanying drawings, which are not intended to limit the embodiments of the application.

In describing embodiments of the present application, it should be noted that, unless explicitly stated and limited otherwise, the term "coupled" should be interpreted broadly, for example, as being fixedly coupled, detachably coupled, integrally coupled, mechanically coupled, electrically coupled, directly coupled, or indirectly coupled via an intermediary. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

Example 1

1-2, a femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in-situ analysis system is disclosed, namely a femto-second laser probe sulfide tetrasulfur isotope micro-zone in-situ analysis system is disclosed, and the analysis system comprises the following components sequentially arranged on an analysis gas path:

a femtosecond ultraviolet laser ablation device 100 configured to ablate sulfide aerosol particles from a sample to be tested;

SF ₆ a gas preparation device 200 connected to the gas outlet of the femtosecond ultraviolet laser ablation device 100 and configured to contain sulfide aerosol particles and provide a reaction space, the sulfide aerosol particles and the BrF ₅ The gas reacts in the reaction space to generate SF containing target ₆ A mixture of gases;

SF ₆ enrichment and purification device 300, and SF ₆ The gas outlet of the gas preparation device 200 is connected and configured to collect the target SF in the purified gas mixture ₆ A gas;

gas isotope ratio mass spectrometer 500, gas isotope ratio mass spectrometer 500 is coupled to SF through diverter valve assembly 400 ₆ The enrichment and purification device 300 is connected for measuring the target SF ₆ Polysulfide isotope composition of gas.

In this embodiment, the femtosecond ultraviolet laser ablation apparatus 100 has a femtosecond laser 101, a laser ablation platform 103, and a first helium gas source 107; a sample cell for containing a sample to be tested is arranged in the laser ablation platform 103, and the femtosecond laser 101 is configured to emit femtosecond ultraviolet laser to the surface of the sample to be tested in the sample cell so as to ablate sulfide aerosol particles from the sample to be tested; the first helium source 107 is configured to provide a helium carrier gas to blow out ablated sulfide aerosol particles from the sample cell.

In one alternative embodiment, the femto-second ultraviolet laser ablation device 100 further includes a camera 104, and the camera 104 is used to observe and determine the position, shape and size of the object to be ablated, so as to realize online real-time observation of the sample ablation process.

Because the fundamental frequency pulse width of the laser adopted by the current commercial femtosecond laser ablation system at home and abroad is relatively wide, the laser irradiated to the surface of the sample may not be the femtosecond laser in practice due to the pulse broadening effect in the frequency doubling process. In order to ensure that the laser irradiated to the sample surface after frequency multiplication is still femtosecond laser, in this embodiment, the femtosecond laser 101 adopts a solvent Ace type ultrafast femtosecond laser of American Spectra-Physics company, the fundamental frequency output pulse width is less than 120fs@777nm, and the ultraviolet laser pulse width output after frequency multiplication is less than 240fs@194nm, so that the laser irradiated to the sample surface is still femtosecond ultraviolet laser. The laser ablation platform 103 employs a RESOUSION SL 193nm excimer nanosecond laser ablation platform manufactured by ASI, australia. According to the embodiment, the femtosecond ultraviolet laser is introduced into the response SL 193nm excimer nanosecond laser ablation system, the femtosecond ultraviolet laser ablation system and the response SL 193nm excimer nanosecond laser ablation system are organically linked and combined to form the novel femtosecond ultraviolet laser ablation device, the advantages of the femtosecond ultraviolet laser ablation device and the novel femtosecond ultraviolet laser ablation device are fully exerted, and the ablation effect of the ultraviolet laser can be improved.

In this embodiment, SF ₆ The gas production apparatus 200 includes a mini nickel fluorination reactor 201 and a BrF ₅ A gas cylinder 202 and a second helium source 204; brF (BrF) ₅ A gas cylinder 202 is connected to the mini nickel fluorination reactor 201 for providing the BrF required for the reaction ₅ A gas; second helium source 204 and BrF ₅ A gas cylinder 202 is connected and configured to provide helium to dilute the BrF fed to the micro nickel fluorination reactor 201 ₅ A gas; sulfide aerosol particles and BrF ₅ The gases react in the mini-nickel fluorination reactor 201 to produce a gas containing target SF ₆ A mixture of gases.

Further, brF ₅ The gas outlet of the gas bomb 202 is connected with a stainless steel capillary, and the stainless steel capillary is connected with the inlet of the micro nickel fluorination reactor 201 through a three-way valve 205. Preferably, the stainless steel capillary tube has an inner diameter of 0.13mm and a length of 10m, and is helium diluted with BrF ₅ And the mixture enters the micro nickel reactor through a three-way valve at the flow rate of 0.01 ml/min.

In this example, a mini nickel fluorination reactor 201 is used to collect an aerosol sample and fluorinate SF ₆ And (3) gas. As shown in fig. 4, the mini-nickel fluorination reactor 201 comprises a pure nickel tube 2011, wherein an inlet of the pure nickel tube 2011 is used for allowing helium carrier gas to carry sulfide aerosol particles into the pure nickel tube 2011, and an outlet of the pure nickel tube 2011 is used for allowing reaction generated gas containing target SF ₆ The mixed gas of the gases flows out; the inside of the pure nickel pipe 2011 comprises a first space and a second space, wherein the first space is empty and is not filled with reaction materials; the second space is communicated with the outlet of the pure nickel pipe 2011 and is filled with CoF ₃ Powder 2012 and Ni powder 2013, with Ni powder 2013 being closer to the outlet of pure nickel tube 2011; coF (CoF) ₃ Is a solid fluorinating agent, releases fluorine F when heated ₂ Absorption of excess BrF at low temperatures ₅ Equal fluorinating agent, ni powder absorbs excessive BrF ₅ NiF formation with an isofluorinating agent ₂ ，NiF ₂ Is also a solid fluorinating agent; filling CoF ₃ And Ni powder can collect aerosol particles in the first space, avoid loss, accelerate fluorination, ensure complete reaction, and absorb residual BrF ₅ Etc. to prevent corrosion of the purification system, etc.; the mini nickel fluorination reactor 201 adopts an external heating mode, an external heating component is arranged outside the pure nickel tube 2011, and the reaction working temperature is 680 ℃. Preferably, the pure nickel tube 2011 has an outer diameter of 6.4mm, an inner diameter of 3.0mm and a length of 400mm. The micro nickel fluorination reactor 201 with the structure can collect all aerosol particles, and has better and more thorough reaction effect.

With continued reference to fig. 4, in this embodiment, the SF ₆ The gas preparation device 200 further comprises a first cold trap 203, wherein the first cold trap 203 is arranged at the gas outlet of the mini-nickel fluorination reactor 201 and SF ₆ Between the gas inlets of the enrichment purification device 300, for example, the gas outlet of the mini-nickel fluorination reactor 301 is connected to the first cold trap 203 using a flexible PTFE tube, reacting residual BrF ₅ The impurity gases are frozen and collected in the first cold trap 203.

Further, SF ₆ The gas preparation apparatus 200 is provided with a plurality of valves on the connection line, specifically, the outlet of the first cold trap 203 and the SF ₆ Pipeline between air inlets of enrichment purification device 300A valve V1 is provided thereon, and the valve V1 is provided with a valve outlet 206. When the test is completed, the first cold trap 203 is warmed up to freeze the frozen matter BrF in the first cold trap 203 ₅ The impurity gases are heated and sublimated, and the sublimated gas valve exhaust port 206 is discharged for harmless treatment; brF (BrF) ₅ A valve V2 is arranged on a pipeline between the three-way valves 205 at the air outlet of the air cylinder 202; second helium source 204 and BrF ₅ A valve V3 is provided in the line between the cylinders 202. The valves V2-V3 not only can control the communication state of the corresponding air paths, but also can adjust the air flow and the flow speed.

In this embodiment, SF ₆ Enrichment and purification device 300 is capable of targeting SF ₆ The gas is enriched and purified for a plurality of times, SF ₆ The enrichment and purification device 300 comprises a first enrichment and purification assembly and a second enrichment and purification assembly, and a gas chromatographic column 305 is arranged between the first enrichment and purification assembly and the second enrichment and purification assembly; the first enrichment and purification assembly and the second enrichment and purification assembly each comprise a six-way valve and a temperature-adjustable liquid nitrogen cold trap. The six-way valve is provided with six valve ports, wherein the first valve port is an air inlet valve port, the second valve port is an air outlet valve port of target gas, the third valve port and the fourth valve port are respectively connected with two opening ends of the temperature-adjustable liquid nitrogen cold trap, the fifth valve port is connected with a back-blowing helium pipeline, and the sixth valve port is an exhaust gas outlet.

Specifically, the first enrichment purification module has a first six-way valve 301 and a second cold trap 302, the intake port of the first six-way valve 301 and the SF ₆ The gas outlet of the gas preparation device 200 is communicated, specifically, the gas inlet valve port of the first six-way valve 301 is communicated with the outlet of the first cold trap 203 through a valve V1, and two valve ports of the first six-way valve 301 are connected with two opening ends of the second cold trap 302; the second cold trap 302 is provided with a first liquid nitrogen barrel; the second enrichment purification module has a second six-way valve 303 and a third cold trap 304; the air outlet valve port of the second six-way valve 303 is connected with the air inlet of the micro valve 401 of the diverter valve assembly 400 through a Teflon pipe, and the two valve ports of the second six-way valve 303 are connected with the two opening ends of the third cold trap 304; the gas chromatographic column 305 is arranged between the first six-way valve 301 and the second six-way valve 303, and the gas chromatographic column 305 is connected with the air outlet valve port of the first six-way valve 301 and the air inlet valve of the second six-way valve 303A mouth; the third cold trap 304 is provided with a second liquid nitrogen barrel.

Further, the gas chromatography column had a temperature of 90℃and a length of 30cm and a diameter of 1/8 inch.

Further, the second cold trap 302 and the third cold trap 304 further comprise heating means for heating the cold traps to rapidly defrost releasing SF ₆ . Release SF when thawing is required ₆ When the cold trap is taken out from liquid nitrogen, a heating device is started to heat the cold trap, and the frozen solid SF is frozen ₆ Sublimating into gas when heated.

As shown in fig. 5, the diverter valve assembly 400 includes a micro valve 401 and a fourth cold trap 402, a valve port one of the micro valve 401 is connected to an air outlet of the second enrichment and purification assembly, and is specifically connected to an air outlet valve port of the second six-way valve 303, a valve port two of the micro valve 401 is connected to an inlet of the fourth cold trap 402, and an outlet of the fourth cold trap 402 is connected to the gas isotope mass spectrometer 500; the third valve port of the micro valve 401 is a waste gas outlet 403, which is communicated with the atmosphere. SF may be enabled using diverter valve assembly 400 ₆ More centralized, further improves the sensitivity and the accuracy of the method.

In this embodiment, the analysis system further includes a reference gas sampling system, the reference gas sampling system adopts a two-way sampling system 600, and during the test process, three groups of reference gases are sent to the gas isotope ratio mass spectrometer 500 through the two-way sampling system, and the sampling time of each group of reference gases is t ₁ The interval time between every two groups of reference gases is t ₂ 。

The embodiment also discloses a femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region in-situ analysis method, namely a femto-second laser probe sulfide tetrasulfur isotope micro-region in-situ analysis method, and the femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region in-situ analysis system is used;

The analysis method comprises the following steps:

carrying sulfide aerosol particles into a closed environment using helium carrier gasIn the SF6 gas production apparatus 200, brF diluted with helium gas ₅ The gas reacts to obtain SF-containing gas ₆ A mixture of gases;

removal of SF-containing ₆ Impurity gas in the mixed gas of the gases to obtain pure target SF ₆ Gas, target SF to be purified ₆ The gas is supplied to a gas isotope ratio mass spectrometer 500 for testing, and the test result of the tetrasulfur isotope composition is obtained.

Wherein sulfide aerosol particles are diluted with helium gas, brF ₅ Reacting the gas at 680 ℃; the flow rate of helium carrier gas is 150ml/min; since BrF5 is a strong fluorinating agent, excessive amounts can cause a series of problems for subsequent processing while being susceptible to accidents, in this example, helium diluted BrF ₅ The gas was fed into the micro nickel fluorination reactor 201 through a stainless steel capillary tube having a length of 10m and an inner diameter of 0.13mm at a flow rate of 0.01ml/min to control the concentration and flow rate of the BrF5 gas to prevent an excess.

In this embodiment, a pure target SF is obtained ₆ Gas, target SF to be purified ₆ The gas is fed to a gas isotope ratio mass spectrometer 500 for testing, comprising the steps of:

helium carrier gas carrying SF ₆ The mixed gas of the gases passes through a first cold trap 203 at the temperature of-160 ℃ to remove the residual BrF after the reaction ₅ And impurity gas which can be frozen to obtain primary pure SF ₆ A gas;

primary pure SF ₆ The gas enters a second cold trap 302 at the temperature of minus 196 ℃ and SF ₆ The gas is frozen in the second cold trap 302, primary pure SF ₆ Impurity gas in the gas is discharged from the exhaust gas outlet of the first six-way valve 301; the temperature of the second cold trap 302 is adjusted to minus 130 ℃, meanwhile, the first six-way valve 301 is switched, and the SF released in the second cold trap 302 is carried out by utilizing the first back-flushing helium flow 306 of 20ml/min ₆ The gas is carried and injected into a gas chromatographic column 305, and trace impurity gas is further separated and purified by the chromatographic column to obtain secondary pure SF ₆ A gas; the first back-blowing helium flow 306 adopts 20ml/min, so that the defects that the back-blowing helium flow has poor separation effect and is too small to blow can be avoided.

Secondary pure SF ₆ SF after passing the gas through the gas chromatographic column 305 ₆ The gas is frozen in a third cold trap 304 at-196 ℃, the second six-way valve 303 is switched, the temperature of the third cold trap 304 is adjusted to-180 ℃, and SF is frozen ₆ The gas releases non-freezing impurity gas; the temperature of the third cold trap 304 is adjusted to-130 ℃, and SF released in the third cold trap 304 ₆ The gas is pure target SF ₆ A gas;

the pure target SF is then purged with a second flow of back-flushing helium 307 of 3ml/min ₆ The gas is carried out, enriched by the diverter valve assembly 400 and enters the gas isotope ratio mass spectrometer 500.

For easy understanding, the specific operation steps of the analysis method in this embodiment are further described with reference to two states of the "Load" mode and the "object" mode of the six-way valve in fig. 3:

(1) Sulfide aerosol samples ablated by the femtosecond laser 101 are blown into the micro nickel fluorination reactor 201 by 150ml/min He carrier gas, brF ₅ Reacts with the aerosol sample at 680 ℃ to release SF ₆ 。

(2) The first cold trap 203 is placed in-160 ℃, the second cold trap 302 is placed in liquid nitrogen at-196 ℃, and the first six-way valve 301 is placed in "Load" mode. BrF remaining after the reaction ₅ The impurity gases are frozen and collected in a first cold trap 201 at-160 ℃ and the unfrozen gas SF ₆ As He gas enters the second cold trap 302, it is frozen and collected.

(3)SF ₆ After collection, the temperature of the second cold trap 302 is adjusted to-130 ℃, and simultaneously the first six-way valve 301 is rotated to change from the Load mode to the project mode, and SF is carried out by the back-blowing helium flow of the first path of 20ml/min ₆ The gas is carried out and injected into the gas chromatographic column 305, and the trace impurity gas is further separated and purified through the gas chromatographic column 305.

(4) The second six-way valve 303 is placed in "Load" mode, clean SF ₆ Immediately after passing through the gas chromatography column 305, it was frozen and collected in the third cold trap 304.

(5)SF ₆ After collection, the second six-way valve 303 is rotated first, consisting ofThe Load mode is changed to the reject mode while raising the temperature of the third cold trap 304 to-180 deg.c, freezing SF ₆ The unfrozen impurity gas is released and is exhausted from the second 3ml/min back-flushing helium flow through the exhaust port 403 of the micro valve 401.

(6) Immersing the fourth cold trap 402 in liquid nitrogen after 3min, and raising the temperature of the third cold trap 304 to-130 ℃ to release SF ₆ Carried out by a second reverse-blowing helium flow of 3ml/min, and frozen and enriched in a fourth cold trap Tr at-196 ℃ through a micro valve 401 ₄ Is a kind of medium.

(7) The micro valve 401 is closed, wherein residual helium is pumped from the fourth cold trap 402 of liquid nitrogen through the ion source of the mass spectrometer to avoid the influence of trace impurity gases in helium carrier gas on the m/z 131 signal measurement, and then the fourth cold trap is lifted from the liquid nitrogen to release SF ₆ The tetra-sulfur isotope composition is measured as a short pulse of inlet gas into the gas isotope mass spectrometer 500.

Compared with the prior art, the femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-area in-situ analysis system and method provided by the embodiment have at least one of the following beneficial effects:

1. the invention samples and SF by in-situ ablation of the micro-area of the traditional laser probe ₆ The fluorination preparation of (C) is carried out simultaneously in situ, and is changed into different places and is completed successively, thereby avoiding infrared laser ablation-SF ₆ Fractionation and effects resulting from incomplete reactions and reaction of the fluorinating agent with the matrix component during the preparation process. Aiming at fractionation generated in the process of infrared laser heating and ablation, a femtosecond ultraviolet laser ablation sample without obvious thermal effect and matrix effect is adopted, elements and isotopes are small in fractionation in the ablation process, aerosol particles generated by ablation are uniform in size and high in transmission efficiency, fractionation in the laser ablation and transmission process is avoided and reduced, and the chemical characteristics of the sample can be truly represented, so that the sample does not need to be strictly matched with a standard sample, and compared with nanosecond laser, the femtosecond laser has higher sensitivity and accuracy, and the application range of the femtosecond laser is greatly widened.

2. Adopts an improved miniature nickel fluorination reactor and adopts a temperature-adjustable liquid nitrogen cold trap for the purpose Label SF ₆ The gas is enriched and purified for three times, and the Gas Chromatography (GC) is utilized to further separate the impurity gas before the second enrichment and purification, thereby improving the target SF ₆ The enrichment purity of the gas improves the sensitivity and precision of the test.

3、SF ₆ Viscosity of (C) is less than SO ₂ The memory effect of gas in pipeline transportation can be reduced, the ionization rate in a mass spectrum ion source is high, and the sensitivity is high; fluorine (F) is a monoisotopic element, and is not interfered by homoisobaric element, so that data correction is not needed, the result is more accurate, and the method is a classical method for developing sulfur isotope non-quality fractionation research.

Example 2

As the freezing temperature of the liquid cryogen is certain, such as the freezing temperature of the pure liquid cryogen is-196 ℃ in the prior art, and the freezing temperature range of the liquid nitrogen and ethanol mixed cryogen with different proportions is-120 ℃ to-60 ℃, the freezing environment temperature of the existing cold trap is also certain, and the same cold trap can not realize the requirement of accurate adjustment of the large-scale freezing temperature.

Based on the above-mentioned problems, a further embodiment of the present invention discloses that the first temperature-adjustable liquid nitrogen cold trap 308 and the second temperature-adjustable liquid nitrogen cold trap 309 can replace any one of the first cold trap 203, the second cold trap 302, the third cold trap 304 and the fourth cold trap 402 in embodiment 1, so that not only can accurate adjustment of different freezing temperatures be realized, but also temperature rise after freezing can be realized, and SF is enabled to be realized ₆ The target gas and the impurity gas are separated more thoroughly, and the purity is higher.

As shown in fig. 6, the first type of tunable temperature liquid nitrogen cold trap 308 includes:

a first cryogen space configured to hold a first cryogen medium;

a second cryogen space disposed within the first cryogen space and configured to receive a second cryogen medium having a temperature that is higher than the temperature of the first cryogen medium; the second freezing space is provided with a first inlet and a first outlet, the first inlet is used for allowing the second freezing medium to flow in, and the first outlet is used for allowing the second freezing medium to flow out;

the third refrigerating space is arranged in the second refrigerating space and is provided with a second inlet and a second outlet, the second inlet is used for flowing in the mixed gas containing the target gas, the second outlet is connected with the downstream test gas circuit, unfrozen gas flows out from the second outlet, and the gas obtained by heating and sublimating the frozen solid flows out from the second outlet;

the temperature of the second freezing medium is higher than that of the first freezing medium, the first freezing medium is liquid nitrogen, and the temperature of the liquid nitrogen is-196 ℃; the second freezing medium is nitrogen, such as normal temperature nitrogen.

In this embodiment, the first temperature-adjustable liquid nitrogen cold trap 308 further includes a nitrogen source connected to the first inlet of the second cryogen space via a gas supply tube. Optionally, the nitrogen temperature that the nitrogen source provided is normal atmospheric temperature, and in the use was placed in first freezing medium with nitrogen gas air supply pipeline coiling part, make normal atmospheric temperature nitrogen cooling to need not to set up additionally thermodynamic just can realize carrying out accurate, continuous regulation to the freezing temperature in the second freezing space.

In one alternative embodiment, the first temperature-adjustable liquid nitrogen cold trap 308 comprises a liquid nitrogen barrel 3081 and sleeved outer and inner tubes 3082, 3083; wherein, the containing space in the liquid nitrogen barrel 3081 is a first freezing space, the inner space of the outer tube 3082 is a second freezing space, and the inner space of the inner tube 3083 is a third freezing space; wherein the first cryogen space is configured to hold a first cryogen medium; the second cryogen space is disposed within the first cryogen space and configured to receive a second cryogen medium, and the third cryogen space is disposed within the second cryogen space and configured to pass a gas mixture comprising a target gas.

Specifically, the outer tube 3082 and the inner tube 3083 are both U-shaped tubes, a sealed space 3084 is formed between the inner wall of the outer tube 3082 and the outer wall of the inner tube 3083, the tube orifice of the outer tube 3082 is connected with the outer wall of the inner tube 3083 in a sealed manner, and the two end tube orifices of the inner tube 3083 extend out of the two end tube orifices of the outer tube 3082; wherein, the side wall of the outer tube 3082 is provided with a nitrogen inlet 3082a and a nitrogen outlet 3082b which are communicated with the sealed space 3084, and the nitrogen provided by the nitrogen source flows into the sealed space 3084 from the nitrogen inlet 3082a and flows out from the nitrogen outlet 3082 b; one end of the inner tube 3083 is provided with an air inlet 3083a, the other end is provided with an air outlet 3083b, the air inlet 3083a is used for flowing in mixed gas containing target gas, the air outlet 3083b is connected with a downstream test gas path, unfrozen gas flows out from the air outlet 3083b, and gas obtained by sublimating frozen solid after being heated flows out from the air outlet 3083 b.

In this embodiment, the temperature-adjustable liquid nitrogen cold trap further includes a nitrogen source connected to the nitrogen inlet 3082a of the second cryogen space through a gas supply tube 3085. Optionally, the nitrogen temperature that the nitrogen source provided is normal atmospheric temperature, and in the liquid nitrogen was arranged in to the air supply pipe coiling part during the use, make normal atmospheric temperature nitrogen cooling to need not to additionally set up thermal power and just can realize adjusting the freezing temperature in the second freezing space, can realize freezing the thermal sublimation of solid.

In one alternative embodiment, the air supply pipe 3085 is provided with a flow valve, and the flow valve can control the flow rate and the flow velocity of nitrogen in the air supply pipe 3085 according to the pipe diameters of the inner pipe 3083 and the outer pipe 3082, and simultaneously, the temperature of the nitrogen in the air supply pipe 3085 is controlled in a matched manner, so that the freezing temperature in the second freezing space is accurately, continuously and dynamically adjusted, namely the temperature in the third freezing space is adjusted, the temperature adjusting range is-90 ℃ to-160 ℃, and the adjusting precision is not higher than 1 ℃, thereby meeting the purpose of accurate temperature adjustment.

In one alternative embodiment, at least a portion of the gas supply tube 3085 is located within the liquid nitrogen of the first cryogen space. If the gas supply pipe 3085 with the length of at least about 60cm is immersed in a liquid nitrogen barrel with the temperature of minus 196 ℃, the gas supply pipe 3085 is in contact refrigeration with liquid nitrogen, nitrogen with the temperature reduced is supplied into a sealed space 3084 between the outer pipe 3082 and the inner pipe 3083 through the nitrogen inlet 3082a and flows out from the nitrogen outlet 3082b, the liquid nitrogen medium in the first freezing space and the supplied low-temperature nitrogen jointly cool the inner pipe 3083, so that target gas is frozen in the inner pipe 3083, in the process, the supplied nitrogen plays a role of heating, and the freezing temperature is more stable by immersing part of the gas supply pipe into the liquid nitrogen to reduce the heating speed. In this embodiment, a part of the gas supply pipe 3085 is placed in liquid nitrogen, and the nitrogen flowing in the gas supply pipe 3085 is cooled by using the liquid nitrogen, so that the temperature difference between the nitrogen temperature and the set target temperature is reduced, and the low-temperature of the third freezing space is more stable.

Further, the air supply pipe 3085 is a hose, the air supply pipe 3085 is coiled in the first freezing space, the coiled part is positioned in liquid nitrogen, the cooling time of nitrogen in the air supply pipe 3085 can be prolonged, the temperature of the nitrogen fed into the second freezing space can reach a lower target temperature, and the temperature of the low-temperature nitrogen fed into the second freezing space can be kept consistent.

In this embodiment, the pipe diameter of the outer pipe 3082 is 20-40mm, the pipe diameter of the inner pipe 3083 is 5-7mm, and the pipe diameter of the air supply pipe 3085 is 2-3mm. For example, the tube diameter of the inner tube 3083 is 6.35mm and the tube diameter of the gas supply tube 3085 is 1.6mm.

In one alternative embodiment, a first temperature sensor is provided on the outer wall of the inner tube 3083 for monitoring the temperature within the inner tube 3083 in real time.

In an alternative embodiment, the number of the second freezing spaces is plural, the plural second freezing spaces are sleeved layer by layer from inside to outside, an annular ventilation space is formed between two adjacent second freezing spaces, each annular ventilation space is provided with a first inlet and a first outlet, that is, each annular ventilation space is provided with a nitrogen inlet 3082a and a nitrogen outlet 3082b, nitrogen is independently introduced into each annular ventilation space, and the flow of the nitrogen introduced into each annular ventilation space can be set differently. Further, the first inlet of each annular ventilation space is connected to the air supply pipe through a branch air pipe, and each branch air pipe is provided with a branch flow valve. Through setting up a plurality of second freezing spaces that independently arrange, through nitrogen gas velocity of flow, flow and nitrogen gas temperature in the different second freezing spaces of control, can realize multistage, accuse temperature step by step to can be more accurate, continuous regulation control second freezing space's cooling temperature.

In one alternative embodiment, the plurality of annular plenums are of different volumes, each of which is independent and non-contiguous. The inner wall spacing between two adjacent second freezing spaces is sequentially reduced from outside to inside. Through the volume differentiation setting with a plurality of annular ventilation spaces, and increase in proper order between the inner wall in annular ventilation space from inside to outside, the annular ventilation space that is close to more is narrower, is more sensitive by its inside nitrogen gas temperature, velocity of flow, flow influence, consequently, can promote the accurate regulation to the freezing temperature in the third freezing space through adjusting nitrogen gas temperature, velocity of flow, the flow in annular ventilation space from outside to inside in proper order, further promotes temperature control precision.

When the first temperature-adjustable liquid nitrogen cold trap 308 is implemented, normal-temperature nitrogen is supplied into a sealed space 3084 between an outer pipe 3082 and an inner pipe 3083 by a nitrogen source, because part of an air supply pipe 3085 is positioned in liquid nitrogen, the temperature of the nitrogen is reduced by the liquid nitrogen before the nitrogen is supplied into the sealed space 3084, the flow rate of the nitrogen in the air supply pipe 3085 is controlled by adjusting a flow valve, and the nitrogen supplied into the sealed annular space 3084 can maintain a specific temperature in cooperation with the temperature of the nitrogen, so that a freezing environment for the inner pipe 3083 is formed; the mixed gas containing the target gas enters the inner tube 3083 through the gas inlet 3083a, and the mixed gas is frozen in the bottom of the inner tube 3083 while flowing through the inner tube 3083 because the inner tube 3083 is in the low temperature environment of the sealed space 3084, and the remaining non-target gas flows out through the gas outlet 3083 b. When it is desired to sublimate the solid material into a gaseous state, the outer tube 3082, the inner tube 3083, and the gas supply tube 3085 are taken out of the liquid nitrogen barrel, placed in air, sublimated into a gaseous state at room temperature, or the flow rate of nitrogen in the gas supply tube 3085 is adjusted by a flow valve to raise the temperature of the cold trap to sublimate into a gaseous state.

Compared with the prior art, the first temperature-adjustable liquid nitrogen cold trap 308 provided by the embodiment, the liquid nitrogen in the liquid nitrogen barrel directly cools the nitrogen in the air supply pipe and the sealing space, the low-temperature nitrogen in the annular space freezes the mixed gas in the inner pipe, and the frozen solid is heated and sublimated by adjusting the flow rate of the nitrogen, so that the temperature-adjustable liquid nitrogen cold trap is simple in structure, convenient to operate and low in cost, and unattended operation can be realized.

As shown in fig. 7, the second type of temperature-adjustable liquid nitrogen cold trap 309 includes:

liquid nitrogen container 3091, filled with liquid nitrogen;

the cylinder 3092 has one end open and the other end closed, the open end of the cylinder is positioned below the liquid nitrogen level of the liquid nitrogen container 3091, and the closed end of the cylinder is positioned above the liquid nitrogen level; the closed end of the cylinder 3092 is provided with an exhaust valve 3093, and the inner space of the cylinder 3092 is communicated with the outside atmosphere through the exhaust valve 3093;

the U-shaped enrichment pipe 3094, the U-shaped enrichment pipe 3094 is provided with an air inlet and an air outlet, a U-shaped enrichment section is arranged between the air inlet and the air outlet, the U-shaped enrichment section passes through the closed end of the cylinder body and is arranged in the inner space of the cylinder body, at least one part of the U-shaped enrichment section can be positioned in liquid nitrogen, the air inlet and the air outlet are positioned outside the cylinder body, the air inlet is used for inflow of mixed gas containing target gas, and the air outlet is used for outflow of impurity gas in the freezing process and the target gas after freezing enrichment purification; the U-shaped enrichment section is wound with a heating wire 3095, the heating wire 3095 is a nichrome heating wire, and the heating wire 3095 is used for heating the U-shaped enrichment section; the U-shaped enrichment section is also provided with a thermocouple 3096 for monitoring the temperature of the U-shaped enrichment section;

The temperature controller 3097 is electrically connected with the heating wire 3095 and the thermocouple 3096, and can control the heating temperature and time of the heating wire 3095 according to the temperature information monitored by the thermocouple 3096.

In this embodiment, the opening end of the cylinder 3092 is provided with a reduced diameter, the opening diameter of the cylinder 3092 is smaller than the diameter of the main body portion of the cylinder 3092, and the diameter of the main body portion of the cylinder 3092 is the same as the diameter of the closed end of the cylinder 3092.

In this embodiment, the cylinder 3092 is made of teflon material, the wall of the cylinder 3092 has a certain thickness, preferably, the thickness of the wall of the cylinder 3092 is 3-5cm, and the cylinder 3092 with this thickness can reduce the heat transfer between the inside and the outside of the cylinder 3092 as much as possible, so as to avoid the liquid nitrogen outside the cylinder 3092 from being sublimated due to heating. The U-shaped enrichment pipe 3094 has an outer diameter of 1.5mm, an inner diameter of 1.0mm and a length of 20cm, and can be made of stainless steel pipes or quartz glass pipes, and the outer diameter and the inner diameter can be selected according to actual needs.

In one alternative embodiment, the heating wire 3095 is wound around a U-shaped enrichment section, the U-shaped enrichment section including parallel first and second vertical sections and an arcuate section connecting the first and second vertical sections, the winding density of the heating wire 3095 on the arcuate section being greater than the winding density of the heating wire 3095 on the first and second vertical sections. The structure is arranged in such a way that the frozen matters frozen in the U-shaped enrichment section are also in a U shape, and the frozen matters are mainly concentrated in the arc-shaped section of the U-shaped enrichment section, so that the frozen matters in each part of the U-shaped enrichment section can be sublimated rapidly by winding the heating wires with high density on the arc-shaped section.

When the second temperature-adjustable liquid nitrogen cold trap 309 is implemented, liquid nitrogen with a certain liquid level is filled in a liquid nitrogen container 3091, a cylinder 3092 provided with an exhaust valve 3093 and a U-shaped enrichment pipe 3094 is inverted in the liquid nitrogen container 3091, the open end of the cylinder 3092 is placed below the liquid nitrogen level of the liquid nitrogen container 3091, the closed end of the cylinder is placed above the liquid nitrogen level, the lower part of a U-shaped enrichment section of the U-shaped enrichment pipe 3094 is placed below the liquid nitrogen level, and the U-shaped enrichment section is frozen by liquid nitrogen; the air inlet and the air outlet of the U-shaped enrichment pipe 3094 are respectively connected into a system pipeline; in the initial state, the heater wire 3095 is de-energized and in the unheated state, the top vent valve 3093 is opened to cool the U-shaped enrichment tube 3094 to the same temperature as the liquid nitrogen (-196℃.). When the temperature of the U-shaped enrichment pipe 3094 needs to be raised, the exhaust valve 3093 at the top is closed, the heating wire 3095 is electrified and heated, liquid nitrogen in the inner space of the cylinder 3092 begins to boil, and part of liquid nitrogen sublimates from liquid to gaseous N ₂ Thereby increasing the gas pressure in the inner space of the cylinder 3092, sublimated N ₂ The pressure will apply downward pressure to the liquid level of the liquid nitrogen inside the cylinder 3092, causing the liquid nitrogen inside the cylinder 3092 to be discharged from the bottom open end of the cylinder 3092, and finally from the opening of the liquid nitrogen container to the atmosphere, with the temperature of the internal space of the cylinder 3092 being controlled by the low temperature nitrogen vaporized from the liquid nitrogen inside the cylinder 3092. The heater wire 3095 continues to heat and the thermocouple monitors the temperature of the U-shaped enrichment tube 3094 in real time until the temperature of the U-shaped enrichment tube 3094 reaches a set temperature and maintains the set temperature for a predetermined time. When the temperature of the U-shaped enrichment tube 3094 needs to be reduced, the heating wire 3095 is powered off to stop heating, the top exhaust valve 3093 is opened, nitrogen in the inner space of the cylinder 3092 is discharged, the liquid level of liquid nitrogen in the cylinder 3092 is increased, the U-shaped enrichment section is placed below the liquid level of liquid nitrogen again, and the liquid nitrogen is used for U-shaped enrichment The enrichment section is frozen. The low-temperature freezing temperature or the heating temperature of the U-shaped enrichment section is controlled by a programmable microprocessor using a thermocouple, so that the automatic temperature rising and lowering process can be realized.

Compared with the prior art, the second temperature-adjustable liquid nitrogen cold trap 309 provided in this embodiment adopts triple freezing space design, through arranging the barrel with the exhaust valve and the U-shaped enrichment pipe in the liquid nitrogen container, the space between the outer wall of the barrel and the inner wall of the liquid nitrogen container is the first freezing space, the space between the outer wall of the U-shaped enrichment pipe and the inner wall of the barrel is the second freezing space, the inner space of the U-shaped enrichment pipe is the third freezing space, and through arranging the electric heating wire and the thermocouple on the U-shaped enrichment pipe, one end of the barrel is closed, the other end is opened, the opening end is positioned below the liquid nitrogen liquid level of the liquid nitrogen container, the liquid nitrogen in the second freezing space is heated and sublimated by utilizing the electric heating wire, the liquid nitrogen liquid level in the barrel is lowered, sublimated gas is discharged from the opening end of the barrel, thereby improving the freezing temperatures of the second freezing space and the third space, realizing the temperature adjustment of the cold trap, the whole process can realize automatic control, and the temperature adjustment accuracy is controllable.

Example 3

The sample cell matched with the existing RESOUTION excimer ultraviolet laser ablation system is a double-chamber sample cell, the structure of the sample cell is shown in FIG. 8, the existing double-chamber sample cell comprises an existing sample cell I and an existing sample cell II 2, the existing sample cell I is located below the existing sample cell II 2, the existing sample cell I is connected with a helium source through a helium carrier gas path, a sample inlet is formed in the bottom of the existing sample cell II 2 and communicated with the existing sample cell I, an argon inlet pipeline 21 and an argon outlet pipeline 22 are arranged on the side wall of the existing sample cell II 2, the argon inlet pipeline 21 is used for supplying argon to the existing sample cell II 2, and the air outlet pipeline 22 is communicated with a reaction tube. Wherein, a target frame is arranged in the first sample cell 1, a helium carrier gas path is communicated with the space of the target frame, the target frame is moved to align a certain sample to be degraded with the second sample cell 106 during testing, an excimer laser is utilized to degrade aerosol particles containing a target object from the sample to be degraded in the first sample cell 1, the degraded aerosol particles are positioned in the first sample cell 1, helium is supplied into the first sample cell 1, and the degraded aerosol particles in the first sample cell 1 are purged and carried into the second sample cell 2 by helium gas flow and flow out from the gas outlet pipeline 22 into a reaction tube. However, the existing second sample cell 2 with the double-chamber sample cell structure needs two carrier gases of He and Ar during the test, and needs to purge the aerosol particles degraded in the existing first sample cell 1 into the existing second sample cell 2 by adopting a high-flow helium flow and an argon flow with the flow rate of more than 1000ml/min, wherein the Ar gas has 2 functions: (1) Ar gas is working gas in plasma, which must be provided, or else, the plasma cannot be formed, (2) Ar gas is heavier than He gas, he gas carries aerosol particles to flow from bottom to top, ar gas flows from top to bottom, and the Ar gas are mutually matched to enable the aerosol particles to be intensively blown out from the middle outlet of the second sample pool and enter the reaction tube, but the flow rate of He carrier gas of the laser ablation-gas isotope mass spectrometry stable isotope micro-area in-situ analysis system cannot exceed 200ml/min, so that high-flow helium gas does not meet the requirement of LA-IRMS stable isotope micro-area in-situ analysis, and the aerosol cannot be completely blown out when the flow rate of helium gas is reduced.

Aiming at the technical problems existing in the existing double-chamber sample cell, the embodiment provides the following two improved sample cells:

the first modified cell is a single cell, the single cell is an elliptical cell 102, and the degraded aerosol particles can be transferred to SF with maximum efficiency by using a small carrier gas flow rate ₆ The micro nickel fluorination reactor 201 of the gas preparation apparatus 200 improves the sensitivity and can avoid the positional effect in the sample stripping process. The analysis system in fig. 1 is provided with an elliptical sample cell, see fig. 9 to 10, the elliptical sample cell 102 comprising:

base one 1023, base one 1023 is provided with a chamber 1024, and the cross section of chamber 1024 is elliptical;

the cross section of the first target frame 1027 is oval, the first target frame 1027 is detachably arranged in the chamber 1024, the outer wall surface of the first target frame 1027 can be attached to the chamber wall surface of the chamber 1024, the first target frame 1027 is provided with a plurality of test points 1030, and the centers of the test points 1030 are equidistantly arranged on the long axis of the oval;

the air inlet channel 1021 and the air outlet channel 1022 are coaxially arranged, the air inlet channel 1021 and the air outlet channel 1022 are horizontally arranged at two ends of the base 1023, and the axes of the air inlet channel 1021 and the air outlet channel 1022 are coincident with or parallel to the long axis of the ellipse; the inlet passage 1021 supplies helium carrier gas to flow into the chamber 1024, and the outlet passage one 1022 supplies helium carrier gas to flow out with sulfide aerosol particles;

MgF ₂ Glass one 1026, locate above base one 1023, cover and seal the top opening of cavity 1024 locating in base one 1023;

a top cover 1025 arranged on MgF ₂ Above the first glass 1026, a transparent window is provided in the center of the first top cap 1025, and all the test points 1030 are located in the longitudinal projection area of the transparent window.

In this embodiment, the elliptical sample cell 102 is designed with a small volume, the elliptical major axis of the chamber 1024 is 42mm, and the minor axis is 15mm; the test points 1030 are circular, the number of the test points 1030 is 4, and the radius of the circular test points 1030 is 4.5mm; the gap between two adjacent test points 1030 is 0.5mm; the depth of the chamber 1024 is 13mm and the diameters of the inlet passage 1021 and the outlet passage one 1022 are 3-5mm.

When the oval sample cell is used for testing, the femtosecond laser 101 erodes sulfide aerosol particles from a sample to be tested in the oval sample cell 102, he carrier gas is blown into a cavity 1024 of the oval sample cell from an air inlet channel 1021 at one end of the oval sample cell at a certain flow rate, and is blown out from an air outlet channel 1022 at the other end of the oval sample cell to enter a micro nickel fluorination reactor 201; because the cross section shape of the chamber 1024 is elliptical, the gas flow is smoother, no dead angle exists, the aerosol blowing efficiency is high, the blowing efficiency of each test point 1030 is the same, so that the position effect is effectively avoided, the small-volume design can ensure that degraded aerosol particles are transmitted to the gas preparation device with the maximum efficiency by using the small carrier gas flow rate, and the sensitivity is improved.

In order to improve the tightness of the oval sample cell, the oval sample cell 102 further comprises a sealing ring 1028, wherein the sealing ring 1028 is an oval sealing ring, preferably a silicone rubber sealing ringThe cross section of the ring, the sealing ring 1028 is elliptical, the cross section of the sealing ring 1028 is of a T-shaped structure, and the sealing ring 1028 can be understood to comprise an elliptical sealing ring main body and an elliptical convex ring arranged on the elliptical sealing ring main body, the top surface of the first base 1023 and the bottom surface of the first top cover 1025 are both provided with grooves 1029 matched with the elliptical convex ring, the grooves 1029 are elliptical grooves, the elliptical convex ring can be arranged in the elliptical grooves, and the top surface of the first base 1023 and MgF are provided with grooves 1029 matched with the elliptical convex ring ₂ A first sealing ring is arranged between the first 1026 pieces of glass, mgF ₂ And a second sealing ring is arranged between the bottom surfaces of the first glass 1026 and the first top cover 1025, and the sealing cavity is sealed by using the two sealing rings 1028, so that the sealing performance is better.

Further, the oval convex ring has a trapezoid cross section, and correspondingly, the oval grooves on the top surface of the first base 1023 and the bottom surface of the first top cover 1025 have a trapezoid cross section, and the groove bottom area of the groove 1029 is larger than the notch area of the groove, and the structure enables the extrusion force between the oval convex ring and the side wall of the oval groove to be increased when the first top cover 1025 and the first base 1023 are fixedly locked, so that the tightness can be further improved, and MgF can be prevented ₂ The glass breaks.

Furthermore, the lower end surface of the first top cover 1025 is further provided with a cylindrical side wall, the outer peripheral surface of the top of the first base 1023 is provided with a yielding space for yielding the cylindrical side wall, the yielding space is provided with a transverse end surface, the transverse end surface is provided with a threaded hole, the cylindrical side wall of the first top cover 1025 can be sleeved and installed at the top of the first base 1023, the cylindrical side wall of the first top cover 1025 is provided with a through hole in a penetrating manner, and the first top cover 1025 is fixedly connected with the transverse end surface of the first base 1023 by a screw; mgF (MgF) ₂ The cross-sectional dimensions of glass one 1026, the oval seal, and the cylindrical side wall match, i.e., when the cap one 1025 is snapped onto the MgF ₂ After the first glass 1026 and the first base 1023 are arranged, the inner wall of the cylindrical side wall and MgF ₂ The side peripheral wall surface of the first glass 1026 and the side peripheral surfaces of the upper and lower seal rings are in contact. The above structure is arranged to make MgF ₂ The first glass 1026 and the upper and lower sealing rings are both positioned in the cylindrical side wall of the first top cover 1025, and a plurality of end surfaces of the sealing rings play a role in sealingWith better tightness.

Further, the intake passage 1021 has a first gas inlet connected to a helium source and a first gas outlet in communication with the chamber 1024; the first outlet channel 1022 has a second gas inlet in communication with the chamber 1024 and a second gas outlet in communication with the inlet of the mini nickel fluorination reactor 201. Wherein, from the first gas inlet to the first gas outlet, the aperture of the gas inlet channel 1021 is gradually increased; the pore size of the first outlet channel 1022 becomes smaller gradually from the second gas inlet to the second gas outlet. It can be also understood that the air inlet channel 1021 and the air outlet channel 1022 are both bell-mouthed, and the opening at one end communicated with the chamber 1024 is large, and the opening at the other end is small, so that helium carrier gas enters the chamber 1024 of the elliptical sample cell in a divergent mode when entering the chamber 1024 from the air inlet channel 1021, and flows into the chamber 1024 as close to the inner wall of the elliptical sample cell as possible, and gas in the chamber 1024 flows into the air outlet channel 1022 as close to the inner wall of the elliptical sample cell as possible, so that the purging blind area of the helium carrier gas can be further reduced, and the purging efficiency is improved.

Compared with the prior art, the elliptical sample cell provided by the embodiment has the advantages of no position effect and stable high transmission efficiency, and can ensure that the test points of all parts are influenced by the blowing flow speed to be the same, thereby effectively avoiding the position effect, and ensuring that the degraded sulfide aerosol particles are transmitted to SF (sulfur hexafluoride) with maximum efficiency by a small-volume design ₆ And the gas preparation device improves the sensitivity.

The second improved sample cell is a dual-chamber sample cell specially used for stable isotope micro-area in-situ analysis, and the dual-chamber sample cell is different from the dual-chamber sample cell of the existing response excimer ultraviolet laser ablation system in that the second sample cell 106 adopted in the embodiment is different from the structure of the second existing sample cell 2, and the volume of the second sample cell 106 in the embodiment is smaller, the blowing efficiency of laser ablation aerosol is higher under the condition of low flow rate, the cleaning speed is high, the working efficiency is high, and no position effect exists. The analysis system in fig. 2 is provided with a dual-chamber sample cell, as shown in fig. 11 to 13, which includes:

the first sample cell 105, the first sample cell 105 is connected with helium source through helium carrier gas path 1051, the first sample cell 105 is provided with movable target frame two 1052, the target frame two 1052 can move along X and Y axes, the stepping resolution is <1 μm; the second target frame 1052 is used for placing a plurality of sample targets to be degraded, and can be used for placing sample targets with different sizes and shapes, so that the sample targets do not need to be replaced frequently, and the working efficiency is improved;

The second sample cell 106, the second sample cell 106 is located above the first sample cell 105, the second sample cell 106 is provided with a cylindrical cavity 1063, two ends of the cylindrical cavity 1063 are open, the bottom end opening of the cylindrical cavity 1063 is a sample inlet, the sample inlet is communicated with the inner space of the first sample cell 105, and the top end opening of the cylindrical cavity 1063 is provided with MgF in a sealing way ₂ Glass two 1065; the second sample cell 106 is provided with a second air outlet channel 1061, an argon inlet pipeline 1041 for argon to enter is not arranged, the second air outlet channel 1061 is obliquely upwards arranged, the second air outlet channel 1061 is provided with a channel inlet 1061a and a channel outlet 1061b, the channel inlet 1061a is positioned on the inner wall of the cylindrical cavity 1063 and communicated with the cylindrical cavity 1063, the channel outlet 1061b is positioned on the top end surface of the second base 1062, and the channel outlet 1061b is communicated with the inlet of the mini nickel fluorination reactor 201 through a Teflon tube 1069.

Further, the inclination angle of the second air outlet channel 1061 is 40-50 °, which indicates the included angle between the axis of the second air outlet channel 1061 and the axis of the cylindrical chamber 1063, the second air outlet channel 1061 is bell-mouth-shaped, the diameter of the channel inlet 1061a is larger than that of the channel outlet 1061b, the channel inlet 1061a is uniformly variable-diameter from the channel outlet 1061b to the channel outlet 1061a, the diameter of the channel outlet 1061b is 2mm, the diameter of the channel inlet 1061a is 4mm, and the second air outlet channel 1061 with bell-mouth-shaped structure can make the purged aerosol particles blow out of the sample cell more easily.

In this embodiment, the second sample cell 106 includes a second base 1062 and MgF ₂ A second glass 1065 and a second top cover 1064, a cylindrical chamber 1063 disposed within the second base 1062, mgF ₂ The second glass 1065 is fixed on the top end surface of the second base 1062 through the second top cover 1064, mgF ₂ The second glass 1065 can completely transmit 193nm ultraviolet light, and the second base 1062 is aluminum alloyJin Caizhi, the inner wall of the cylindrical cavity 1063 is smooth, so that the degraded aerosol particles can be ensured to be completely blown out of the second sample cell 106, and the influence of the degraded sample residues on the next test result is effectively avoided.

In this embodiment, the diameter of the cylindrical chamber 1063 of the second sample cell 106 is 4mm, and the volume of the cylindrical chamber 1063 of the second sample cell 106 is 0.15ml, so that the dead volume can be reduced, and the sample transfer efficiency can be effectively increased. The distance between the bottom opening of the cylindrical chamber 1063 and the top surface of the sample target is reduced from-2 mm to-1 mm, further improving the blowing efficiency of aerosol particles.

In this embodiment, mgF ₂ A third sealing ring 1067 is arranged between the second glass 1065 and the second base 1062, the third sealing ring 1067 is a circular sealing ring, the top surface of the second base 1062 is provided with a first circular groove, and the third sealing ring 1067 is arranged in the first circular groove; the second top cover 1064 is fixedly connected with the second base 1062 through a bolt, a containing groove is formed in the lower end face of the second top cover 1064, and MgF is arranged on the lower end face of the second top cover ₂ The diameter of the second glass 1065 is smaller than the diameter of the accommodating groove, and MgF is formed when the second top cover 1064 is fixed on the second base 1062 ₂ The second glass 1065 is secured within the receiving slot of the second top cover 1064. Alternatively, mgF ₂ A sealing ring is also arranged between the second glass 1065 and the bottom of the accommodating groove of the second top cover 1064 so as to further improve the sealing performance and prevent MgF ₂ Glass two 1065 is crushed.

Further, a mounting groove is formed in the top end surface of the first sample cell 105, a top sample outlet of the first sample cell 105 is formed in the bottom surface of the mounting groove, the second sample cell 106 is mounted in the mounting groove of the first sample cell 105, the outer contour of a second base 1062 of the second sample cell 106 is matched with the shape of the groove wall of the mounting groove, and a bottom sample inlet of the cylindrical cavity 1063 is aligned and communicated with the sample outlet of the first sample cell 105; in order to improve the tightness, the installation groove of the first sample tank 105 is a stepped groove, the lower diameter of the installation groove is small, the upper diameter of the installation groove is large, the installation groove is provided with an upward stepped end face, correspondingly, the lower diameter of the second base 1062 of the second sample tank 106 is small, the upper diameter of the installation groove is large, the installation groove is provided with a downward stepped end face, a fourth sealing ring 1068 is installed between the stepped end face of the installation groove of the first sample tank 105 and the stepped end face of the second base 1062, and optionally, a second circular groove is arranged on the stepped end face of the second base 1062, and the fourth sealing ring 1068 is installed in the second circular groove.

Compared with the prior art, the improved double-chamber sample cell provided by the embodiment adopts a micro-volume straight-through design, the chamber of the second sample cell is in a horn shape with a large upper part and a small lower part, and the structure of a step at the middle outlet is obviously different from that of the original chamber of the second sample cell, the diameter, the height and the volume of the inner chamber of the second sample cell are reduced, the diameter is reduced from 30mm to 4mm, the height is reduced from 40mm to 12mm, the volume is reduced from about 35ml to 0.15ml, the distance between the bottom end of the second sample cell and the top surface of a sample target is reduced from 2mm to 1mm, the carrier gas is changed from 2 paths to 1 path, ar carrier gas is removed, the inclination angle of an air outlet channel II is 40-50 degrees, the structural design ensures that the flow rate of the carrier gas is reduced from more than the original 1000ml/min to about 150ml/min, the transmission efficiency of the stripped aerosol sample can be rapidly carried away from the sample chamber of the second sample cell to enter a micro nickel fluoride reactor, and the micro-in-IRMS stable isotope analysis requirement of LA-in situ area is met.

The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the application, and is not meant to limit the scope of the application, but to limit the application to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the application are intended to be included within the scope of the application.

Claims

1. The femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in-situ analysis system is characterized by comprising the following components in sequence on an analysis gas path:

a femtosecond ultraviolet laser ablation device (100) configured to ablate sulfide aerosol particles from a sample to be tested in a sample cell;

SF ₆ a gas preparation device (200) connected with the gas outlet of the femtosecond ultraviolet laser ablation device (100) and configured toAccommodating sulfide aerosol particles and providing a reaction space, the sulfide aerosol particles and BrF ₅ The gas reacts in the reaction space to generate SF containing target ₆ A mixture of gases;

SF ₆ enrichment and purification device (300), and SF as described ₆ A gas outlet connection of a gas preparation device (200) configured to collect and purify a target SF in the gas mixture ₆ A gas;

a gas isotope ratio mass spectrometer (500), the gas isotope ratio mass spectrometer (500) is connected with SF through a diverter valve assembly (400) ₆ An enrichment purification device (300) is connected for measuring the target SF ₆ A polysulfide isotope composition of a gas;

wherein, the sample cell is two room sample cells, include:

the first sample pool (105), the first sample pool (105) is connected with a helium gas source through a helium carrier gas path (1051), a second target frame (1052) is arranged in the first sample pool (105), and the second target frame (1052) is used for placing a plurality of sample targets to be degraded;

The second sample cell (106), the second sample cell (106) is located the top of first sample cell (105), second sample cell (106) have cylindrical cavity (1063), cylindrical cavity (1063) both ends opening, cylindrical cavity (1063) bottom opening is the sample inlet, sample inlet and the interior space intercommunication of first sample cell (105), cylindrical cavity (1063) top opening seals and is equipped with MgF ₂ Glass two (1065); the second sample tank (106) is provided with a second air outlet channel (1061) which is obliquely upwards arranged, the second air outlet channel (1061) is provided with a channel inlet (1061 a) and a channel outlet (1061 b), the channel inlet (1061 a) is positioned on the inner wall of the cylindrical chamber (1063) and communicated with the cylindrical chamber (1063), the channel outlet (1061 b) is positioned on the top end surface of the second base (1062), and the channel outlet (1061 b) is communicated with the SF ₆ The inlet of the gas preparation device (200) is communicated.

2. The femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in-situ analysis system according to claim 1, wherein the femtosecond ultraviolet laser ablation apparatus (100) has a femtosecond laser (101), a laser ablation platform (103), and a first helium gas source (107); a sample pool for containing a sample to be tested is arranged in the laser ablation platform (103), and the femtosecond laser (101) is configured to emit femtosecond ultraviolet laser to the surface of the sample to be tested in the sample pool so as to ablate sulfide aerosol particles from the sample to be tested; the first helium source (107) is configured to provide a helium carrier gas to blow out ablated sulfide aerosol particles from the sample cell.

3. The femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in-situ analysis system of claim 1, wherein the SF ₆ The gas preparation device (200) comprises a micro nickel fluorination reactor (201) and a BrF ₅ A gas cylinder (202) and a second helium source (204);

the BrF is provided with ₅ The gas cylinder (202) is connected with a micro nickel fluorination reactor (201) for providing BrF needed by the reaction ₅ A gas;

the second helium source (204) and BrF ₅ A gas cylinder (202) connected to provide helium to dilute BrF fed to the micro nickel fluorination reactor (201) ₅ A gas;

the sulfide aerosol particles and BrF ₅ The gas reacts in the mini nickel fluorination reactor (201) to generate SF containing target ₆ A mixture of gases.

4. The femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in-situ analysis system of claim 3, wherein the SF ₆ The gas preparation device (200) also comprises a first cold trap (203), wherein the first cold trap (203) is arranged at the gas outlet of the micro nickel fluorination reactor (201) and SF ₆ Between the air inlets of the enrichment and purification device (300);

the SF ₆ The enrichment and purification device (300) comprises a first enrichment and purification assembly, a second enrichment and purification assembly and a gas chromatographic column (305), wherein the gas chromatographic column (305) is arranged between the first enrichment and purification assembly and the second enrichment and purification assembly;

The first enrichment purification assembly has a first six-way valve (301) and a second cold trap (302), and the second enrichment purification assembly has a second six-way valve (303) and a third cold trap (304).

5. The femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in-situ analysis system according to claim 4, wherein the diverter valve assembly (400) comprises a micro valve (401) and a fourth cold trap (402), a valve port of the micro valve (401) is connected with an air outlet of the second enrichment and purification assembly, a valve port of the micro valve (401) is connected with an inlet of the fourth cold trap (402), and an outlet of the fourth cold trap (402) is connected with a gas isotope ratio mass spectrometer (500); the third valve port of the micro valve (401) is an exhaust port (403) which is communicated with the atmosphere.

6. The femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-region in-situ analysis system of claim 5, wherein at least one of the first cold trap (203), the second cold trap (302), the third cold trap (304), and the fourth cold trap (402) is a temperature-adjustable liquid nitrogen cold trap;

the adjustable temperature liquid nitrogen cold trap comprises:

a liquid nitrogen container (3091) filled with liquid nitrogen;

a cylinder (3092), wherein one end of the cylinder (3092) is open, the other end of the cylinder is closed, the open end of the cylinder (3092) is positioned below the liquid nitrogen level of the liquid nitrogen container (3091), and the closed end of the cylinder (3092) is positioned above the liquid nitrogen level; the closed end of the cylinder body (3092) is provided with an exhaust valve (3093), and the inner space of the cylinder body (3092) is communicated with the outside atmosphere through the exhaust valve (3093);

The U-shaped enrichment pipe (3094), the U-shaped enrichment pipe (3094) is provided with an air inlet and an air outlet, a U-shaped enrichment section is arranged between the air inlet and the air outlet, the U-shaped enrichment section passes through the closed end of the cylinder body and is arranged in the inner space of the cylinder body, at least one part of the U-shaped enrichment section can be positioned in liquid nitrogen, the air inlet and the air outlet are positioned outside the cylinder body, the air inlet is used for inflow of mixed gas containing target gas, and the air outlet is used for outflow of mixed gas in the freezing process and the target gas after freezing enrichment and purification; a heating wire (3095) is wound on the U-shaped enrichment section; the U-shaped enrichment section is also provided with a thermocouple (3096) for monitoring the temperature of the U-shaped enrichment section;

the temperature controller (3097) is electrically connected with the heating wire (3095) and the thermocouple (3096) and can control the heating temperature and time of the heating wire (3095) according to the temperature information monitored by the thermocouple (3096);

or,

the adjustable temperature liquid nitrogen cold trap comprises:

a first cryogen space configured to hold a first cryogen medium;

the temperature of the second freezing medium is higher than that of the first freezing medium, the first freezing medium is liquid nitrogen, and the second freezing medium is normal-temperature nitrogen.

7. A femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in-situ analysis method, characterized in that the femtosecond ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone in-situ analysis system according to any one of claims 1-6 is used;

the analysis method comprises the following steps:

helium carrier gas is used for carryingThe sulfide aerosol particles are carried into SF under a closed environment ₆ In the gas preparation device (200), brF diluted with helium ₅ The gas reacts to obtain SF-containing gas ₆ A mixture of gases;

Removing the SF-containing ₆ Impurity gas in the mixed gas of the gases to obtain pure target SF ₆ Gas, purifying the target SF ₆ And (3) feeding the gas into a gas isotope ratio mass spectrometer (500) for testing to obtain a test result of the tetrasulfur isotope composition.

8. The method for in-situ analysis of a femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone of claim 7, wherein a flow rate of said helium carrier gas is 150ml/min.

9. The method of in situ analysis of femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone of claim 7, wherein said helium diluted BrF ₅ The gas is supplied into SF through a stainless steel capillary tube at a flow rate of 0.01ml/min ₆ In a gas preparation apparatus (200).

10. The method of in situ analysis of femto-second ultraviolet laser ablation-gas isotope mass spectrometry sulfide tetrasulfur isotope micro-zone of any one of claims 7 to 9, wherein said obtaining a pure target SF is achieved ₆ Gas, purifying the target SF ₆ A gas feed gas isotope ratio mass spectrometer (500) for testing, comprising the steps of:

helium carrier gas carrying the SF-containing gas ₆ The mixture of gases is passed through a first cold trap (203) at-160 ℃ to obtain primary pure SF ₆ A gas;

the primary pure SF ₆ The gas enters a second cold trap (302) at the temperature of minus 196 ℃ and SF ₆ The gas is frozen in a second cold trap (302), primary pure SF ₆ Impurity gas in the gas is discharged from an exhaust gas outlet of the first six-way valve (301); regulating the temperature of the second cold trap (302) to-130 ℃ while switching the first sixA through valve (301) for utilizing 20ml/min of a first back-blowing helium flow (306) to release SF released in the second cold trap (302) ₆ The gas is carried and injected into a gas chromatographic column (305) to obtain a secondary pure SF ₆ A gas;

the secondary pure SF ₆ SF after passing the gas through a gas chromatographic column (305) ₆ The gas is frozen in a third cold trap (304) at-196 ℃, a second six-way valve (303) is switched, the temperature of the third cold trap (304) is regulated to-180 ℃, and SF is frozen ₆ The gas releases non-freezing impurity gas; regulating the temperature of the third cold trap (304) to-130 ℃, and releasing SF in the third cold trap (304) ₆ The gas is pure target SF ₆ A gas;

the pure target SF is purged with a second flow of back-flushing helium (307) of 3ml/min ₆ The gas is carried out, enriched in a fourth cold trap at the temperature of minus 196 ℃ through a flow dividing valve assembly (400), and thawed and enters a gas isotope ratio mass spectrometer (500).