CN116413104B - System and method for in-situ analysis of carbonate carbon-oxygen isotope micro-region by ultraviolet laser ablation-gas isotope mass spectrometry - Google Patents

System and method for in-situ analysis of carbonate carbon-oxygen isotope micro-region by ultraviolet laser ablation-gas isotope mass spectrometry Download PDF

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CN116413104B
CN116413104B CN202310332415.8A CN202310332415A CN116413104B CN 116413104 B CN116413104 B CN 116413104B CN 202310332415 A CN202310332415 A CN 202310332415A CN 116413104 B CN116413104 B CN 116413104B
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gas
carbonate
isotope
laser ablation
ultraviolet laser
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CN116413104A (en
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胡斌
范昌福
郭东伟
李延河
孙成鹏
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Institute of Mineral Resources of Chinese Academy of Geological Sciences
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Institute of Mineral Resources of Chinese Academy of Geological Sciences
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/34—Purifying; Cleaning
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/40—Concentrating samples
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/40—Concentrating samples
    • G01N1/4022—Concentrating samples by thermal techniques; Phase changes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/40—Concentrating samples
    • G01N1/4044—Concentrating samples by chemical techniques; Digestion; Chemical decomposition
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • G01N27/64—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

The application relates to an ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon oxygen isotope micro-region in-situ analysis system and method, wherein ultraviolet laser with the wavelength of 193nm is utilized to ablate carbonate aerosol particles from a sample to be detected in a closed environment; carrying the degraded carbonate aerosol particles into CO in a closed environment by helium carrier gas 2 The reaction is carried out in a gas preparation device to obtain the catalyst containing CO 2 A mixture of gases; for CO-containing 2 The mixed gas of the gases is enriched and purified to obtain target CO 2 A gas; targeted CO using a blowback helium gas flow 2 The gas is supplied into the gas isotope ratio mass spectrometer through the micro split-flow interface, and the test result is obtained through measurement. The invention separates the traditional laser probe micro-area in-situ sampling and the analysis gas preparation, the laser ablation adopts 193nm ultraviolet laser with small thermal effect and small matrix effect, the size of aerosol particles formed by ablation is uniform, the transmission efficiency is high, and the occurrence of fractionation in the laser ablation and transmission process is avoided and reduced.

Description

System and method for in-situ analysis of carbonate carbon-oxygen isotope micro-region by ultraviolet laser ablation-gas isotope mass spectrometry
Technical Field
The application belongs to the technical field of carbonate carbon-oxygen isotope analysis, and particularly relates to an ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon-oxygen isotope micro-region in-situ analysis system and method.
Background
Laser ablation-gas isotope mass spectrometry is also known as Laser probe (Laser Microprobe) stable isotope micro-area in-situ analysis. The principle of the traditional laser probe carbonate carbon and oxygen isotope micro-region in-situ analysis method is as follows: focusing a high energy infrared laser beam through an optical system onto selected micro-areas of a sample sheetHeating micro-area carbonate sample by using thermal effect of infrared laser to directly decompose CO 2 Gas (CaCO) 3 →CaO+CO 2 ) After purification and chromatographic separation, the carbon and oxygen isotopes are introduced into a sample injection system of a gas isotope mass spectrometer to be measured.
However, the in situ analysis of carbonate carbon and oxygen isotopes by using a conventional infrared laser probe has the following two unavoidable and difficult problems: (1) CaCO when the infrared laser probe heats the sample 3 Decomposition into CO 2 And CaO. In the infrared laser micro-zone heating process, only part of heated carbonate is decomposed due to temperature gradient and boundary effect, obvious fractionation is generated, and accurate correction is difficult. (2) The analysis results of carbon and oxygen isotopes by the laser heating method have certain differences from the analysis results by the traditional phosphoric acid method, and the correction values are required to be corrected, so that the correction values are not completely the same for samples with different properties. The obvious unavoidable and difficult accurate correction fractionation exists in the in-situ analysis of the carbonate carbon-oxygen isotope microdomains of the infrared laser probe, so that the further improvement of the analysis precision and accuracy is influenced, and the development of the analysis technology is restricted.
In addition, since the existing laser ablation multi-receiving inductively coupled plasma mass spectrometry (LA-MC-ICPMS) micro-area in-situ analysis is performed in the atmosphere, O in the air 2 、CO 2 The concentration is high, and the atmospheric influence is difficult to avoid, so that the existing laser ablation multi-receiving inductively coupled plasma mass spectrometry (LA-MC-ICPMS) carbonate carbon and oxygen isotope micro-area in-situ analysis has difficulty.
Disclosure of Invention
In view of the above, the present invention is directed to an in-situ analysis system and method for carbonate carbon-oxygen isotope microdomains by ultraviolet laser ablation-gas isotope mass spectrometry, that is, an in-situ analysis system and method for carbonate carbon-oxygen isotope microdomains by ultraviolet laser probe, which are used to solve one or more of the above problems in the prior art.
The purpose of the invention is realized in the following way:
in one aspect, an in-situ analysis system for carbon-oxygen isotope microdomains of carbonate by ultraviolet laser ablation-gas isotope mass spectrometry is provided, which comprises the following steps:
the ultraviolet laser ablation device is provided with a 193nm excimer laser and a sample cell, and the sample cell is used for containing a sample to be tested; 193nm excimer laser is used to ablate carbonate aerosol particles from the sample to be tested in the sample cell;
CO 2 The gas preparation device is provided with a reaction space, and carbonate aerosol particles are carried by helium carrier gas into the reaction space and react in the reaction space to generate CO-containing gas 2 A mixture of gases;
CO 2 gas enrichment and purification device for enriching and purifying target CO in mixed gas 2 A gas;
a miniature shunt interface;
gas isotope ratio mass spectrometer, through miniature shunt interface and CO 2 The gas enrichment and purification device is connected.
Further, CO 2 The gas preparation device comprises an acidolysis device, wherein the acidolysis device comprises an acidolysis container and an acidolysis heater for heating the acidolysis container; the acidolysis container comprises an outer pipe and an inner pipe which are coaxially arranged, wherein one end of the outer pipe is open, and the other end of the outer pipe is closed and is used for accommodating phosphoric acid; the two ends of the inner tube are opened, phosphoric acid is added into the outer tube, helium carrier gas is supplied to carry carbonate aerosol particles into the phosphoric acid, one end opening of the inner tube is positioned in the outer tube and is close to the bottom of the outer tube, the other end opening of the inner tube is positioned outside the outer tube, and the outer wall of the inner tube is connected with the opening of the outer tube in a sealing way; an annular space is formed between the outer tube and the inner tube, a side wall air outlet tube is further arranged on the side wall of the outer tube, and the side wall air outlet tube is communicated with the annular space;
Further, the acidolysis heater comprises an aluminum alloy heating base, an electric heating element and a temperature controller, wherein the top surface of the aluminum alloy heating base is provided with a plurality of heating holes for accommodating acidolysis containers, the electric heating element is arranged on the circumferential side wall of the aluminum alloy heating base in a surrounding manner, and the temperature controller is electrically connected with the electric heating element in a control manner and is used for controlling the heating temperature during acidolysis reaction;
alternatively, CO 2 The gas preparation device comprises a high-temperature cracking device, wherein the high-temperature cracking device comprises a reaction tube and a high-temperature cracking furnace, and the reaction tube is arranged in the high-temperature cracking furnace; the middle part of the reaction tube is filled with quartz wool.
Further, the sample cell is an elliptical sample cell; alternatively, the sample cell is a dual-chamber sample cell.
Further, the ultraviolet laser ablation device also comprises a first cold trap, and the first cold trap is arranged on a gas path between the helium carrier gas inlet and the sample cell;
CO 2 the gas preparation device also comprises a water trap or a low-temperature cold trap at-60 ℃, wherein the water trap or the low-temperature cold trap at-60 ℃ is arranged on the CO 2 Upstream of the gas inlet of the gas enrichment and purification device.
Further, CO 2 The gas enrichment and purification device comprises a six-way valve and a second cold trap; the first valve port of the six-way valve is communicated with the outlet of the water trap, and the second valve port of the six-way valve is connected with the micro diversion interface through a Teflon pipe; the third valve port and the fourth valve port of the six-way valve are respectively connected with two opening ends of the second cold trap; the fifth valve port of the six-way valve is connected with a back-blowing helium pipeline, and a third cold trap is arranged on the back-blowing helium pipeline; the sixth valve port of the six-way valve is an exhaust gas outlet.
Further, the low-temperature cold trap and the third cold trap at the temperature of minus 60 ℃ are adjustable liquid nitrogen cold traps; the temperature-adjustable liquid nitrogen cold trap comprises a liquid nitrogen barrel, an outer pipe and an inner pipe; the inner space of the liquid nitrogen barrel is a first freezing space; the inner space of the outer tube is a second freezing space; the inner space of the inner tube 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; the first freezing medium is liquid nitrogen and the second freezing medium is nitrogen.
On the other hand, the invention also provides an ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon-oxygen isotope micro-region in-situ analysis method, and the ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon-oxygen isotope micro-region in-situ analysis system adopting the technical scheme is provided; the analysis method comprises the following steps:
using ultraviolet laser with the wavelength of 193nm to degrade carbonate aerosol particles from a sample to be tested in a closed environment;
carrying the degraded carbonate aerosol particles into CO in a closed environment by helium carrier gas 2 The reaction is carried out in a gas preparation device to obtain the catalyst containing CO 2 A mixture of gases;
for CO-containing 2 The mixed gas of the gases is enriched and purified to obtain target CO 2 A gas;
targeted CO using a blowback helium gas flow 2 The gas is supplied into the gas isotope ratio mass spectrometer through the micro split-flow interface, and the test result is obtained through measurement.
Further, CO-containing is obtained by acidolysis reaction 2 A mixture of gases; wherein 100% phosphoric acid is adopted in acidolysis reaction, and the acidolysis reaction temperature is 110+/-0.2 ℃.
Further, CO-containing is obtained by pyrolysis reaction 2 A mixture of gases; wherein the pyrolysis temperature is 1020 ℃.
Further, the flow rate of the back-blowing helium flow is 1-3 mL/min.
Compared with the prior art, the ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon-oxygen isotope micro-region in-situ analysis system and method provided by the invention can at least realize one of the following beneficial effects:
a) The micro-area in-situ sampling and the analysis gas preparation of the traditional laser probe are carried out separately, the original design defects of the traditional laser probe technology are overcome, 193nm ultraviolet laser with small thermal effect and small matrix effect is adopted for laser ablation, so that aerosol particles formed by ablation are uniform in size, the transmission efficiency is high, and fractionation in the laser ablation and transmission processes is avoided and reduced.
b) The target particles are degraded out in a closed sample cell, and then helium carrier gas is used for carrying the target particles into CO 2 In the gas preparation device, CO is produced by reaction 2 Gas, CO is obtained 2 Avoiding O in air during gas process 2 、CO 2 Entering and contaminating target CO 2 And the accuracy of the test result is improved by the gas.
c) The analysis gas is prepared by adopting a classical phosphoric acid method, so that fractionation and influence caused by incomplete reaction in the preparation process of the analysis gas are avoided.
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 an ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon-oxygen isotope micro-zone in-situ analysis system (high-temperature acidolysis);
FIG. 2 is a schematic structural diagram of an ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon-oxygen isotope micro-zone in-situ analysis system (pyrolysis) provided by the invention;
FIG. 3 is a schematic view of the structure of an ultraviolet laser ablation apparatus employing a dual chamber cuvette in accordance with the present invention;
fig. 4 is a schematic structural diagram of an acidolysis container provided by the invention;
fig. 5 is a schematic structural diagram of an acidolysis heater provided by the invention;
FIG. 6 is a schematic diagram of a prior art dual chamber sample cell;
FIG. 7 is a schematic diagram of a dual-chamber sample cell according to the present invention;
FIG. 8 is a schematic diagram of a second sample cell of the dual-chamber sample cell provided by the present invention;
FIG. 9 is a schematic view showing an oval sample cell according to the present invention;
fig. 10 is a schematic view of a target holder of an elliptical sample cell provided by the invention mounted in a base.
Fig. 11 is a schematic structural diagram of a temperature-adjustable liquid nitrogen cold trap provided by the invention.
Reference numerals:
100. an ultraviolet laser ablation device; 101. 193nm excimer 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 target 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 cold trap;
200、CO 2 a gas preparation device; 201. a reaction tube; 201a, quartz cotton; 202. an acidolysis container; 202b, an outer tube; 202a, an inner tube; 202c, a side wall air outlet pipe; 203. a water trap; 204. acidolysis heater; 204a, an aluminum alloy heating base; 204b, an electric heating element; 204c, heating holes; 206. a cold trap at 60 ℃;
300、CO 2 a gas enrichment and purification device; 301. a six-way valve; 302. a second cold trap; 303. back blowing a helium pipeline; 304. a third cold trap; 305. a temperature-adjustable liquid nitrogen cold trap; 3051. a liquid nitrogen barrel; 3052. an outer tube; 3052a, nitrogen inlet; 3052b, nitrogen outlet; 3053. an inner tube; 3053a, air inlet; 3053b, air outlet; 3054. sealing the space; 3055. an air supply pipe;
400. a miniature shunt interface;
500. a gas isotope ratio mass spectrometer;
600. and the double-path sample injection system.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the 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. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
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, in which the embodiments are not intended to limit the embodiments of the present application.
In describing embodiments of the present invention, 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 invention can be understood by those of ordinary skill in the art according to the specific circumstances.
The terms "top," "bottom," "above … …," "below," and "on … …" are used throughout the description to refer to the relative positions of components of the device, such as the relative positions of the top and bottom substrates inside the device. It will be appreciated that the devices are versatile, irrespective of their orientation in space.
Example 1
1-3, an in-situ analysis system of ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon-oxygen isotope micro-area is disclosed, namely an in-situ analysis system of ultraviolet laser probe carbonate carbon-oxygen isotope micro-area is disclosed, and the sub-systems comprise the following components sequentially arranged on an analysis gas path:
An ultraviolet laser ablation device 100 having a 193nm excimer laser 101 and a sample cell for holding a sample to be tested; 193nm excimer laser 101 is used to ablate carbonate aerosol particles from the sample to be tested in the sample cell;
CO 2 the gas preparation apparatus 200 has a reaction space into which carbonate aerosol particles are carried by helium carrier gas and react in the reaction space to produce CO-containing gas 2 A mixture of gases;
CO 2 a gas enrichment and purification device 300 for enriching and purifying target CO in the mixed gas 2 A gas;
a micro shunt interface 400;
gas isotope ratio mass spectrometer 500, through micro-split interface 400 and CO 2 The gas enrichment and purification device 300 is connected.
In this embodiment, CO 2 The gas can be prepared by either acidolysis of phosphoric acid or pyrolysis, so that corresponding CO 2 The gas preparation apparatus 200 has the following two structures:
CO of the first structure 2 A gas preparation apparatus 200 including an acidolysis apparatus including an acidolysis container 202 and an acidolysis heater 204 for heating the acidolysis container 202; as shown in fig. 4, the acidolysis vessel 202 comprises an outer tube 202b and an inner tube 202a coaxially arranged, wherein one end of the outer tube 202b is open, and the other end is closed for containing phosphoric acid; the two ends of the inner tube 202a are opened, which is used for adding phosphoric acid into the outer tube 202b and for helium carrier gas to carry carbonate aerosol particles into the phosphoric acid, the phosphoric acid liquid level exceeds the lower end opening of the inner tube 202a, so that the carbonate aerosol particles carried by the helium carrier gas fully react with the phosphoric acid, one end opening of the inner tube 202a is positioned in the outer tube 202b and is close to the bottom of the outer tube 202b, the other end opening of the inner tube 202a is positioned outside the outer tube 202b, and the outer wall of the inner tube 202a is in sealing connection with the opening of the outer tube 202 b; an annular space is formed between the outer tube 202b and the inner tube 202a, and a side wall air outlet tube 202c is further arranged on the side wall of the outer tube 202b, and the side wall air outlet tube 202c is communicated with the annular space. The joints of the outer tube 202b, the inner tube 202a and the side wall air outlet tube 202c of the acidolysis container 202 with the structure are all of a sealing structure, and are preferably integrally formed, so that the tightness is good.
Further, as shown in fig. 5, the acidolysis heater 204 includes an aluminum alloy heating base 204a, an electric heating element 204b and a temperature controller, wherein a plurality of heating holes 204c are formed in the top surface of the aluminum alloy heating base 204a, the aperture of each heating hole is larger than or equal to the outer diameter of the outer tube 202b, the heating holes 204c are used for accommodating the acidolysis container 202, the electric heating element is enclosed on the circumferential side wall of the aluminum alloy heating base 204a, and the temperature controller is electrically connected with the electric heating element 204b in a control manner and is used for controlling the heating temperature during acidolysis reaction.
CO of the second structure 2 The gas preparation device 200 comprises a high-temperature cracking device, wherein the high-temperature cracking device comprises a reaction tube 201 and a high-temperature cracking furnace, the reaction tube 201 is arranged in the high-temperature cracking furnace, the high-temperature cracking furnace is formed by reforming a high-temperature heating furnace of an element analyzer, the heating temperature is controlled by a computer, and the cracking temperature is 1020 ℃; the middle part of the reaction tube 201 is filled with quartz wool 201a.
In one alternative embodiment, the ultraviolet laser ablation apparatus 100 further includes a laser ablation platform 103, a camera 104, and a helium gas source; the position, the shape and the size of the target object to be degraded are observed and determined by using the camera 104, and the online real-time observation of the sample degradation process can be realized; the laser ablation platform 103 is provided with a sample cell for holding a sample to be tested, and a helium source provides helium carrier gas to blow out ablated aerosol particles from the sample cell.
In this embodiment, the ultraviolet laser ablation apparatus 100 further includes a first cold trap 107, where the first cold trap 107 is a liquid nitrogen cold trap, and the first cold trap 107 is disposed on a gas path between a helium carrier gas inlet and the sample cell, and is used for removing CO in the He carrier gas 2 And the blank background of the system is reduced.
To remove H in the mixed gas 2 O and prevention of phosphoric acid vapor from entering CO 2 Corrosion six-way valve in gas enrichment and purification device 300, CO in this embodiment 2 The gas preparation device 200 also comprises a water trap 203 or a low-temperature cold trap 206 at minus 60 ℃, wherein the water trap 203 or the low-temperature cold trap 206 at minus 60 ℃ is arranged at CO 2 On the upstream gas path of the gas inlet of the gas enrichment and purification device 300, wherein the water trap 203 is filled with magnesium perchlorate, and the cryogenic cold trap 206 at-60 ℃ adopts an adjustable temperature cold trap.
In this embodiment, CO 2 The gas enrichment purification device 300 comprises a six-way valve 301 and a second cold trap 302; wherein, the first valve port of the six-way valve 301 is communicated with the outlet of the water trap 203, the first valve port is an air inlet valve port, the second valve port of the six-way valve 301 is an air outlet valve port of target gas, and the second valve of the six-way valve 301 is a valve port of the target gasThe port is connected with the micro shunt interface 400 through a Teflon tube; the third valve port and the fourth valve port of the six-way valve 301 are respectively connected with two opening ends of the second cold trap 302; the fifth valve port of the six-way valve 301 is connected with a back-blowing helium pipeline 303, and a third cold trap 304 is arranged on the back-blowing helium pipeline 303; the sixth port of the six-way valve 301 is an exhaust outlet. Wherein, the second cold trap 302 and the third cold trap 304 are both liquid nitrogen cold traps, and trace CO in the back-flushing helium carrier gas can be removed by arranging the liquid nitrogen cold traps on the back-flushing helium pipeline 303 2 The blank background of the system can be reduced.
In one alternative embodiment, -60 ℃ cryotrap 206 and third cold trap 304 are temperature adjustable liquid nitrogen cold trap 305. Specifically, as shown in fig. 11, the temperature-adjustable liquid nitrogen cold trap 305 includes a liquid nitrogen barrel 3051, and an outer tube 3052 and an inner tube 3053 which are sleeved; wherein, the accommodation space in the liquid nitrogen barrel 3051 is a first freezing space, the inner space of the outer tube 3052 is a second freezing space, and the inner space of the inner tube 3053 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. The temperature of the second freezing medium is higher than that of the first freezing medium, the first freezing medium is liquid nitrogen, the temperature of the liquid nitrogen is-196 ℃, and the second freezing medium is normal-temperature nitrogen.
Specifically, the outer tube 3052 and the inner tube 3053 are both U-shaped tubes, a sealed space 3054 is formed between the inner wall of the outer tube 3052 and the outer wall of the inner tube 3053, a tube orifice of the outer tube 3052 is connected with the outer wall of the inner tube 3053 in a sealing manner, and two end tube orifices of the inner tube 3053 extend out of two end tube orifices of the outer tube 3052; wherein, the side wall of the outer tube 3052 is provided with a nitrogen inlet 3052a and a nitrogen outlet 3052b which are communicated with the sealed space 3054, and nitrogen provided by a nitrogen source flows into the sealed space 3054 from the nitrogen inlet 3052a and flows out from the nitrogen outlet 3052 b; one end of the inner tube 3053 is an air inlet 3053a, the other end is an air outlet 3053b, the air inlet 3053a is used for flowing in mixed gas containing target gas, the air outlet 3053b is connected with a downstream test gas path, unfrozen gas flows out from the air outlet 3053b, and gas obtained by sublimating frozen solid through heating flows out from the air outlet 3053 b.
In this embodiment, the temperature-adjustable liquid nitrogen cold trap 305 further includes a nitrogen source connected to the nitrogen inlet 3052a of the second freezing space through a gas supply pipe 3055. Optionally, the nitrogen temperature that the nitrogen source provided is normal atmospheric temperature, and in the liquid nitrogen was arranged in to the portion of coiling nitrogen gas air supply pipe 3055 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 solid and be heated the sublimation.
In an alternative embodiment, the air supply pipe 3055 is provided with a flow valve, and the flow valve can control the flow and the flow rate of nitrogen in the air supply pipe 3055, and simultaneously control the temperature of the nitrogen in the air supply pipe 3055 in a matching manner according to the pipe diameters of the inner pipe 3053 and the outer pipe 3052, so that the freezing temperature in the second freezing space can be accurately, continuously and dynamically adjusted, namely, the temperature in the third freezing space is adjusted, the adjusting precision is not higher than 1 ℃, and the purpose of accurately adjusting the temperature is achieved.
In one alternative embodiment, at least a portion of the gas supply pipe 3055 is located within the liquid nitrogen of the first cryogen space. For example, an air supply pipe 3055 with a length of at least about 60cm is immersed in a liquid nitrogen barrel with a temperature of-196 ℃, the air supply pipe 3055 is refrigerated by contact with liquid nitrogen, nitrogen with a reduced temperature is supplied into a sealed space 3054 between an outer pipe 3052 and an inner pipe 3053 through a nitrogen inlet 3052a and flows out from a nitrogen outlet 3052b, liquid nitrogen medium in a first freezing space and the supplied low-temperature nitrogen jointly cool the inner pipe 3053, so that target gas is frozen in the inner pipe 3053, in the process, the supplied nitrogen plays a role of heating, and the freezing temperature is more stable by immersing part of the air supply pipe of nitrogen in the liquid nitrogen to reduce the heating speed. In this embodiment, a part of the gas supply pipe 3055 is placed in liquid nitrogen, and the nitrogen flowing in the gas supply pipe 3055 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 3055 is a hose, the air supply pipe 3055 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 3055 can be prolonged, the temperature of the nitrogen supplied into the second freezing space can be ensured to reach a lower target temperature, and the temperature of the supplied low-temperature nitrogen can be kept consistent.
In this embodiment, the pipe diameter of the outer pipe 3052 is 20-40 mm, the pipe diameter of the inner pipe 3053 is 5-7 mm, and the pipe diameter of the air supply pipe 3055 is 2-3 mm. For example, the inner tube 3053 has a tube diameter of 6.35 mm and the air supply tube 3055 has a tube diameter of 1.6 mm.
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.
In one alternative embodiment, a first temperature sensor is provided on the outer wall of the inner tube 3053 for monitoring the temperature within the inner tube 3053 in real time.
In practice, nitrogen at normal temperature is supplied into a sealed space 3054 between an outer pipe 3052 and an inner pipe 3053 from a nitrogen source through a nitrogen inlet 3052a, and because a part of an air supply pipe 3055 is positioned in liquid nitrogen, the nitrogen is cooled by the liquid nitrogen before being supplied into the sealed space 3054, and the flow rate of the nitrogen in the air supply pipe 3055 is controlled through a flow valve adjustment, and the nitrogen supplied into the annular sealed space 3054 can be maintained at a specific temperature in cooperation with the temperature of the nitrogen, so that a freezing environment for the inner pipe 3053 is formed; the mixed gas containing the target gas enters the inner tube 3053 through the gas inlet 3053a, and the mixed gas is frozen at the bottom of the inner tube 3053 during the process of flowing through the inner tube 3053 because the inner tube 3053 is in the low-temperature environment of the sealed space 3054, and the rest of the non-target gas flows out through the gas outlet 3053 b. When solid matter is required to sublimate into a gaseous state, the outer tube 3052, the inner tube 3053 and the air supply tube 3055 are taken out from the liquid nitrogen barrel and placed in air, and sublimated into a gaseous state at room temperature, or the flow rate of nitrogen in the air supply tube 3055 is regulated by a flow valve, and the temperature of the cold trap is increased to sublimate into the gaseous state.
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 。
Compared with the prior art, the ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon-oxygen isotope micro-region in-situ analysis system and method provided by the embodiment have at least one of the following beneficial effects:
1. the in-situ sampling of the laser ablation micro-area and the preparation of the analysis gas are simultaneously carried out from the original place to the different place, so that the fractionation caused by incomplete reaction and the carbonate pyrolysis process is avoided, the system background is reduced, and the precision and the accuracy of the analysis method are improved. Aiming at fractionation generated in the laser heating and melting process, 193nm ultraviolet laser with small thermal effect and small matrix effect is adopted to degrade a sample, aerosol particles generated by the ablation are uniform in size and high in transmission efficiency, and fractionation generated in the laser ablation and transmission process is avoided and reduced.
2. CO of the present embodiment 2 Gas enrichment and purification device capable of greatly improving CO 2 The gas utilization rate and the sensitivity of the system can meet the in-situ high-precision, high-resolution and high-efficiency test of carbon and oxygen isotope micro-regions of carbonate samples.
3. To remove trace CO that is neutralized by He carrier gas and leaks into the system 2 A liquid nitrogen cold trap is arranged between the helium carrier gas inlet and the sample pool, and a liquid nitrogen cold trap is also arranged on the back-blowing helium gas pipeline, so that the blank background of the system is greatly reduced. The results of testing the carbonate carbon-oxygen isotope standard sample show that: 44 CO 2 about 4000-5000 mV, system blank background 70-100 mV, blank bookThe effect of the bottom on the measurement results is substantially negligible.
4. 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 heated sublimation of frozen solids is realized by adjusting the flow rate of the nitrogen, so that the temperature-adjustable liquid nitrogen cold trap has the advantages of simple structure, convenient operation and low cost, and can realize unattended operation; and the temperature of the liquid nitrogen cold trap with adjustable temperature can be accurately set according to the difference between the freezing temperature of the target gas and the freezing temperature of the impurity gas, so that the impurity gas can be effectively separated and purified.
Example 2
The invention discloses an in-situ analysis method of carbonate carbon-oxygen isotope microdomains by ultraviolet laser ablation-gas isotope mass spectrometry, namely an in-situ analysis method of carbonate carbon-oxygen isotope microdomains by an ultraviolet laser probe, which uses an in-situ analysis system of carbonate carbon-oxygen isotope microdomains by ultraviolet laser ablation-gas isotope mass spectrometry in the embodiment 1, and comprises the following steps:
using ultraviolet laser with wavelength of 193 nm to degrade carbonate aerosol particles from a sample to be tested in a closed environment;
the degraded carbonate aerosol particles are carried into CO in a closed environment by helium carrier gas of 150 ml/min 2 The reaction is performed in the gas production apparatus 200 to obtain a gas containing CO 2 A mixture of gases;
by CO 2 The gas enrichment and purification device 300 is used for enriching CO 2 The mixed gas of the gases is enriched and purified, the freezing and enrichment process lasts 180s, and CO 2 The target CO is obtained after the frozen matter is heated and sublimated 2 A gas;
sublimating heated target CO using a back-blowing helium gas flow 2 The gas is carried out and is fed into the gas isotope ratio mass spectrometer 500 through the low-flow channel and the needle valve of the micro split-flow interface 400 to carry out carbon-oxygen isotope measurement, so that a test result is obtained.
Preferably, a back-blowing helium flow of 1-3 mL/min is utilized to sublimate the heated targetCO 2 The gas is carried out, the background is the lowest in the range, and the sensitivity and the precision are the highest.
In this embodiment, the laser ablation parameters of the ultraviolet laser to ablate the sample to be tested are: energy Density 2J/cm 2 The ablation frequency was 10 Hz, the ablation diameter was 80 μm, and the ablation time was 30 s.
In this embodiment, CO 2 The gas may be produced in either of two ways:
first CO 2 In the gas preparation mode, in CO 2 CO-containing gas obtained by acidolysis reaction in the gas production apparatus 200 2 A mixture of gases; wherein 100% phosphoric acid is adopted in acidolysis reaction, and the acidolysis reaction temperature is 110 ℃.
Second kind of CO 2 In the gas preparation mode, in CO 2 CO-containing gas obtained by pyrolysis in the gas production apparatus 200 2 A mixture of gases; wherein the pyrolysis temperature is 1020 ℃.
Compared with the prior art, the ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon oxygen isotope micro-region in-situ analysis method provided by the embodiment samples the micro-region of the traditional laser probe in situ and CO to be analyzed 2
The gas preparation is carried out simultaneously in situ, and is carried out in different places, so that fractionation caused by incomplete reaction and carbonate pyrolysis is avoided, the system background is reduced, and the test precision and the result accuracy are improved. Specifically, the target carbonate particles are firstly degraded out in a closed sample cell, and then helium carrier gas is used for carrying the target carbonate aerosol particles into CO 2 In the gas preparation device, CO is produced by reaction 2 Gas, CO is obtained 2 Avoiding O in air during gas process 2 、CO 2 Entering, for the target CO prepared 2 The gas causes pollution, so that the accuracy of a test result is improved; and the laser ablation adopts 193nm ultraviolet laser, has small thermal effect and matrix effect, and aerosol particles formed by ablation are uniform in size and high in transmission efficiency, so that fractionation in the laser ablation and transmission processes is avoided and reduced, and the accuracy of a test result is improved.
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. 6, 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 during testing to align a certain sample to be degraded with the second sample cell 2, an excimer laser is utilized to degrade aerosol particles containing target objects 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 the helium carrier gas and flow out from the air 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 the high flow rate helium carrier gas does not meet the requirement of LA-IRMS stable isotope micro-area in-situ analysis, and the reduction of the flow rate of helium carrier gas cannot completely blow out aerosol.
Aiming at the technical problems existing in the existing double-chamber sample cell, the embodiment provides a double-chamber sample cell specially used for stable isotope micro-area in-situ analysis, which is applied to the analysis systems and methods of the embodiment 1 and the embodiment 2, and the double-chamber sample cell is different from the double-chamber sample cell of the existing solution excimer ultraviolet laser ablation system in that the second sample cell 106 adopted in the embodiment is different from the existing sample cell II 2 in structure, and the volume of the second sample cell 106 is smaller in the embodiment, 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 of fig. 1 is provided with a dual-chamber sample cell, as shown in fig. 7 to 8, which includes:
the first sample cell 105, the first sample cell 105 is connected with a helium source through a helium carrier gas path 1051, a movable second target frame 1052 is arranged in the first sample cell 105, the second target frame 1052 can move along X and Y axes, and the stepping resolution is less than 1 mu m; 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 acidolysis device or the pyrolysis device 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, the second base 1062 is made of aluminum alloy, the inner wall of the cylindrical cavity 1063 is smooth, and the degraded aerosol particles can be ensured to be completely blown out of the second sample cell 106, so that the influence of the residue of the degraded sample 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 cavity 1063 and the top surface of the sample target is reduced from 2mm to 1mm, so that the blowing efficiency of aerosol particles is further improved.
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 tank provided by the embodiment adopts a micro-volume straight-through design, the chamber of the second sample tank is in a horn shape with a large upper part and a small lower part, the structure of the middle outlet is obviously different from that of the original chamber of the second sample tank, the diameter, the height and the volume of the inner chamber of the second sample tank are reduced from 40mm to 12mm, the diameter is reduced from 40mm to 12mm, the volume is reduced from 35 ml to 0.15ml, the distance between the bottom end of the second sample tank 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 the second outlet channel is 40-50 degrees, the structural design ensures that the flow rate of He carrier gas is reduced to about 150ml/min from more than the original 1000 ml/min, the transmission efficiency of aerosol is improved, and the degraded aerosol sample can be rapidly taken into a gas preparation device from the sample chamber of the second sample tank to meet the requirement of stable isotope analysis in situ of LA-IRMS.
Example 4
In yet another embodiment of the present invention, an elliptical sample cell 102 is disclosed, which can be used in place of the dual chamber sample cell of embodiment 3 in the analysis systems and methods of embodiments 1 and 2. The elliptical sample cell 102 uses a small carrier gas flow rate to maximize the efficiency of the ablated aerosol particles Ground transport to CO 2 The reaction space of the gas preparation apparatus 200 improves sensitivity and can avoid a positional effect. The analysis system in fig. 2 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 carbonate 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 elliptical sample cell is used for testing, 193nm excimer laser 101 is used for ablating carbonate aerosol particles from a sample to be tested in elliptical sample cell 102, he carrier gas is blown into a cavity 1024 of the elliptical sample cell from an air inlet channel 1021 at one end of the elliptical sample cell at a certain flow rate, and is blown out from an air outlet channel 1022 at the other end of the elliptical sample cell, and then the mixture is fed into an acidolysis device or a pyrolysis device; 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, the sealing ring 1028 is an oval sealing ring, preferably a silicone rubber sealing ring, the cross section of the sealing ring 1028 is oval, the cross section of the sealing ring 1028 is of a T-shaped structure, and also can be understood that the sealing ring 1028 comprises an oval sealing ring main body and an oval convex ring arranged on the oval 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 a groove 1029 matched with the oval convex ring, the groove 1029 is an oval groove, the oval convex ring can be filled in the oval groove, and the top surface of the first base 1023 and MgF are matched with each other 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 also 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, and the cylindrical side wall of the first top cover 1025 is provided with a threaded holeThe top cover can be sleeved and arranged at the top of the first base 1023, a through hole is formed in the tubular side wall of the first top cover 1025 in a penetrating manner, and the first top cover 1025 is fixedly connected with the transverse end face of the first base 1023 by using 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 1026 of glass and two upper and lower sealing washer all are located the tubular side wall of top cap one 1025, and a plurality of terminal surfaces of sealing washer all play sealed effect, so the leakproofness is better.
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 passage 1022 has a second gas inlet in communication with the chamber 1024 and a second gas outlet in communication with an inlet in the acidolysis device or pyrolysis device. 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 rate to be the same, thereby effectively avoiding the position effect, ensuring that the degraded carbonate aerosol particles are transmitted to the gas preparation device with maximum efficiency by the small-volume design, and improving the sensitivity.
The foregoing embodiments have been provided for the purpose of illustrating the general principles of the present application, and are not meant to limit the scope of the invention, but to limit the scope of the invention.

Claims (9)

1. An ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon oxygen isotope micro-region in-situ analysis system is characterized by comprising the following steps of:
an ultraviolet laser ablation device (100) having a 193nm excimer laser (101) and a sample cell for holding a sample to be tested; -the 193nm excimer laser (101) is used for ablating carbonate aerosol particles from a sample to be tested in the sample cell;
CO 2 A gas preparation device (200) having a reaction space into which carbonate aerosol particles are carried by helium carrier gas and react in the reaction space to form a gas containing CO 2 A mixture of gases;
CO 2 a gas enrichment and purification device (300) for enriching and purifying target CO in the mixed gas 2 A gas;
a micro shunt interface (400);
a gas isotope ratio mass spectrometer (500) connected with CO through the micro-split interface (400) 2 The gas enrichment and purification device (300) is connected;
the CO 2 The gas enrichment and purification device (300) comprises a six-way valve (301) and a second cold trap (302); the third valve port and the fourth valve port of the six-way valve (301) are respectively connected with two opening ends of the second cold trap (302);
the fifth valve port of the six-way valve (301) is connected with a back-blowing helium pipeline (303), and a third cold trap (304) is arranged on the back-blowing helium pipeline (303);
the third cold trap (304) is a temperature-adjustable liquid nitrogen cold trap (305);
the temperature-adjustable liquid nitrogen cold trap (305) comprises a liquid nitrogen barrel (3051), an outer tube (3052) and an inner tube (3053);
the inner space of the liquid nitrogen barrel (3051) is a first freezing space, the inner space of the outer tube (3052) is a second freezing space, and the inner space of the inner tube (3053) is a third freezing space; the first cryogen space is configured to hold a first cryogen medium; a second cryogen space disposed within the first cryogen space configured to receive a second cryogen medium, and a third cryogen space disposed within the second cryogen space configured to pass a gas mixture comprising a target gas; the first freezing medium is liquid nitrogen, and the second freezing medium is nitrogen;
The adjustable temperature liquid nitrogen cold trap (305) further comprises a nitrogen source, the nitrogen source is connected with a nitrogen inlet (3052 a) of the second freezing space through a gas supply pipe (3055), a flow valve is arranged on the gas supply pipe (3055), and at least one part of the gas supply pipe (3055) is located in liquid nitrogen of the first freezing space.
2. The ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon-oxygen isotope micro-zone in-situ analysis system of claim 1, wherein the CO 2 The gas preparation device (200) comprises an acidolysis device and a-60 ℃ low-temperature cold trap (206), wherein the-60 ℃ low-temperature cold trap (206) is arranged in CO 2 An upstream gas path of the gas inlet of the gas enrichment and purification device (300); the acidolysis device comprises an acidolysis container (202) and an acidolysis heater (204) for heating the acidolysis container (202); the acidolysis container (202) comprises an outer tube (202 b) and an inner tube (202 a) which are coaxially arranged, wherein one end of the outer tube (202 b) is open, and the other end of the outer tube is closed and is used for containing phosphoric acid; the two ends of the inner tube (202 a) are opened for adding phosphoric acid into the outer tube (202 b) and for helium carrier gas to carry carbonate aerosol particles into the phosphoric acid, and one end opening of the inner tube (202 a) is positioned in the outer tube (202 b) and is close to the outside The pipe bottom of the pipe (202 b), the opening at the other end of the inner pipe (202 a) is positioned outside the outer pipe (202 b), and the outer wall of the inner pipe (202 a) is in sealing connection with the opening of the outer pipe (202 b); an annular space is formed between the outer tube (202 b) and the inner tube (202 a), a side wall air outlet tube (202 c) is further arranged on the side wall of the outer tube (202 b), and the side wall air outlet tube (202 c) is communicated with the annular space; the acidolysis heater (204) comprises an aluminum alloy heating base (204 a), an electric heating element (204 b) and a temperature controller, wherein a plurality of heating holes (204 c) are formed in the top surface of the aluminum alloy heating base (204 a), the heating holes (204 c) are used for accommodating the acidolysis container (202), the electric heating element is arranged on the circumferential side wall of the aluminum alloy heating base (204 a) in a surrounding mode, and the temperature controller is electrically connected with the electric heating element (204 b) in a control mode and used for controlling heating temperature during acidolysis reaction;
alternatively, the CO 2 The gas preparation device (200) comprises a high-temperature cracking device and a water trap (203), wherein the high-temperature cracking device comprises a reaction tube (201) and a high-temperature cracking furnace, and the reaction tube (201) is arranged in the high-temperature cracking furnace; the middle part of the reaction tube (201) is filled with quartz cotton (201 a); the water trap (203) is arranged in CO 2 Upstream of the gas inlet of the gas enrichment and purification device (300).
3. The ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon oxygen isotope micro-zone in-situ analysis system of claim 1, wherein the sample cell is an elliptical sample cell; or the sample cell is a double-chamber sample cell.
4. The ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon oxygen isotope micro-zone in-situ analysis system of claim 1, wherein the ultraviolet laser ablation device (100) further comprises a first cold trap (107), the first cold trap (107) being disposed on a gas path between a helium carrier gas inlet and the sample cell.
5. The ultraviolet laser ablation-gas isotope mass spectrometry carbonate carbon oxygen isotope micro-region in-situ analysis system according to claim 2, wherein a first valve port of the six-way valve (301) is communicated with an outlet of a water trap (203) or an outlet of a-60 ℃ cryotrap (206), and a second valve port of the six-way valve (301) is connected with a micro shunt interface (400) through a teflon tube; the sixth valve port of the six-way valve (301) is an exhaust gas outlet.
6. An in-situ analysis method of carbon-oxygen isotope microdomains of ultraviolet laser ablation-gas isotope mass spectrometry carbonate, characterized in that the in-situ analysis system of carbon-oxygen isotope microdomains of ultraviolet laser ablation-gas isotope mass spectrometry carbonate is used;
The analysis method comprises the following steps:
using ultraviolet laser with wavelength of 193nm to ablate carbonate aerosol particles from the sample to be detected in a closed environment by an ultraviolet laser ablation device (100);
carrying the degraded carbonate aerosol particles into CO in a closed environment by helium carrier gas 2 The reaction is carried out in a gas preparation device (200) to obtain the CO-containing gas 2 A mixture of gases;
by CO 2 Gas enrichment and purification device (300) for CO-containing gas 2 The mixed gas of the gases is enriched and purified to obtain target CO 2 A gas;
target CO is generated by back-flushing helium flow through a back-flushing helium pipeline (303) 2 The gas is supplied to a gas isotope ratio mass spectrometer (500) through a micro shunt interface (400) and is measured to obtain a test result.
7. The method for in-situ analysis of carbonate carbon-oxygen isotope microdomains by ultraviolet laser ablation-gas isotope mass spectrometry according to claim 6, wherein the method is characterized in that the CO-containing product is obtained by acidolysis reaction 2 A mixture of gases;
wherein 100% phosphoric acid is adopted in acidolysis reaction, and the acidolysis reaction temperature is 110+/-0.2 ℃.
8. The method for in-situ analysis of carbonate carbon-oxygen isotope microdomains by ultraviolet laser ablation-gas isotope mass spectrometry according to claim 6, wherein the method is characterized in that the method comprises the step of obtaining the carbon-oxygen isotope by high-temperature cracking reaction 2 A mixture of gases;
wherein the pyrolysis temperature is 1020 ℃.
9. The method for in-situ analysis of carbonate carbon-oxygen isotope microdomains by ultraviolet laser ablation-gas isotope mass spectrometry of claim 6, wherein the flow rate of back-flushing helium gas flow is 1-3 mL/min.
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