Micro-area in-situ analysis system and analysis method for rare gas in extraterrestrial sample

Abstract

The invention discloses a micro-area in-situ analysis system and analysis method for extraterrestrial sample rare gas. The micro-area in-situ analysis system comprises a gas extraction system, a gas purification unit and a gas analysis unit which are connected in sequence, the gas extraction system comprises a laser sample analysis cavity, a cold trap I and a cold trap II which are connected in sequence; the gas purification unit comprises a third cold trap, an active gas suction device and a fourth cold trap which are connected in sequence; the second cold trap is connected with the third cold trap; and the fourth cold trap is connected with the gas analysis unit. When the system designed by the invention is used for detecting the rare gas of the extraterrestrial sample, not only can the use amount of the sample be reduced, but also rare gas isotope analysis can be efficiently and quickly performed on a single-particle sample on a micron scale, the influence of a matrix and other interference phases commonly existing in the sample can be avoided, and the detection accuracy is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of extraterrestrial rare gas detection, and in particular to a micro-area in-situ analysis system and analysis method for rare gases in extraterrestrial samples. Background Art

[0002] Noble gases include six elements: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). Noble gases have unique chemical inertness and extreme incompatibility. The changes in their chemical and isotopic compositions during geological processes are hardly affected by complex chemical reactions, reduction reactions and biological processes. The noble gases in extraterrestrial samples can be divided into three components based on their genesis: cosmic ray genesis, radioactive genesis and captured noble gases. The study of the composition and isotopes of each component of noble gases has been widely used in important scientific issues such as cosmic ray exposure history, impact collision events, calculation of the relationship between the exposure age of meteorites and the distance from the sun, the irradiation history of chondrules before chondrites were compressed to form parent bodies, the identification of paired meteorites, the sputtering history of planetary meteorites and the relative age of lunar craters. Therefore, the study of noble gases is an important means in the field of astrochemistry and comparative planetology.

[0003] Due to their extremely low content and special chemical properties in samples, rare gases can only be measured in static mode using special rare gas mass spectrometers. In solid rock samples, rare gases are generally present in the form of free molecules in the cracks of rocks / minerals, between mineral particles, in mineral lattices, and in inclusions. The primary process of rare gas analysis is the gas extraction process, that is, extracting the rare gases from the sample storage area. At present, for the analysis of a large number of samples, the heating method (total melting or step-wise heating) is still the preferred classical method, which can obtain rare gases between mineral particles, in mineral lattices, and in inclusions. The step-wise heating method can roughly estimate the specific depth or phase of the gas source sample based on the heating temperature stage. The heating devices currently include a double vacuum heating furnace (Pfander et al., 2014) and a CO2 infrared laser (Wang Ying et al., 2018). Crushing can obtain rare gases between mineral particles and in inclusions. Currently, the main devices for crushing are electromagnetic hammer devices and single static pressure devices. Due to the mechanical inhomogeneity of punching, the crushing method can only remove about 70-80% of the gases in inclusions and rock mineral cracks. Closed-system stepped etching (CSSE) obtains rare gases at different depths and specific phases by controlling the type and concentration of acid (Weiler et al., 1986; Benkert et al., 1993). This method is difficult to establish. Currently, there are only two CSSE devices built by the Swiss Federal Institute of Technology in the world, one for the Swiss Federal Institute of Technology and the other at the University of Manchester. The above methods all get roughly mixed results. Although the source of the released rare gas can be estimated empirically according to different experimental conditions (such as the temperature of the heating method or the type and concentration of the acid in the acid etching method), this will inevitably reduce the accuracy of the data. For different mineral phase analysis needs, mineral phase separation is usually used to make up for the shortcomings of the above methods. Common mineral phase separation methods include crushing and sorting, micro-drilling sampling, liquid nitrogen cooling, ultrasonic crushing and solution immersion. However, there are also regrets. Extraterrestrial samples are often small, small, and precious. Separation is very difficult. Even more special extraterrestrial samples (such as lunar soil particles) are prone to sampling failure even after tedious operation processes.

[0004] Therefore, how to provide a rare gas analysis system suitable for extraterrestrial samples is a problem that needs to be solved by those skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a micro-area in-situ analysis system and analysis method for rare gases in extraterrestrial samples. Compared with traditional sample preparation methods, the analysis system designed by the present invention can not only reduce the amount of sample used, but also can efficiently and quickly perform rare gas isotope analysis on single particle samples at the micron scale, and avoid the influence of matrix and other interfering phases commonly present in the sample, so the detection accuracy is higher.

[0006] In order to achieve the above objectives, one of the objectives of the present invention is to provide a micro-area in-situ analysis system for rare gases in extraterrestrial samples: It includes a gas extraction system, a gas purification unit and a gas analysis unit connected in sequence; Wherein, the gas extraction system comprises a laser sample analysis chamber, a cold trap 1 and a cold trap 2 which are connected in sequence; The gas purification unit comprises a cold trap three, an active gas aspirator and a cold trap four which are connected in sequence; The second cold trap is connected to the third cold trap; The cold trap four is connected to the gas analysis unit; The laser sample analysis cavity comprises a sample chamber and an excimer laser; the excimer laser mainly adopts an ultraviolet laser.

[0007] Preferably, it also includes a residual gas analyzer, a vacuum gauge and a molecular pump, The residual gas analyzer and the vacuum gauge are relatively arranged between the second cold trap and the third cold trap; The molecular pump is connected to the residual gas analyzer.

[0008] Preferably, the active gas getter device is provided with at least an active gas getter 1 and an active gas getter 2 connected in sequence; The active gas getter 1 is connected to the cold trap 3; The active gas getter 2 is connected to the cold trap 4.

[0009] Preferably, it also includes: an atmospheric standard sample system and a standard gas standard sample system; The atmospheric standard sample system and the standard gas standard sample system are both arranged on the same branch of the main path between the active gas getter 1 and the active gas getter 2; Furthermore, the atmosphere standard sample system and the standard gas standard sample system are arranged in parallel.

[0010] Preferably, it also includes: an ultra-low temperature cold trap device and an ion pump; The ultra-low temperature cold trap device and the ion pump are both arranged on different branches of the main path between the cold trap 4 and the gas analysis unit.

[0011] Preferably, it also includes: a plurality of valves, wherein the valves are arranged on the main road and / or the branch road according to the operation requirements.

[0012] Preferably, the valve is provided with at least valve 1 to valve 12; The valve 1 is arranged between the cold trap 1 and the cold trap 2; The valve 2 is arranged between the cold trap 3 and the active gas getter 1; The valve three and the valve four are sequentially arranged at the front end of the atmospheric standard sample system; The valve five and the valve six are sequentially arranged at the front end of the standard gas standard sample system; The valve seven is arranged between the active gas getter one and the active gas getter two; The valve 8 is arranged at the front end of the ion pump; The valve nine and the valve ten are arranged in sequence at the front end of the ultra-low temperature cold trap device, and the valve nine is arranged at the rear end of the cold trap four; The valve eleven is arranged at the front end of the gas analysis unit.

[0013] The second object of the present invention is to provide a micro-area in-situ analysis method for rare gases in extraterrestrial samples, wherein the analysis system is used to analyze the rare gases in extraterrestrial samples, and the method specifically comprises the following steps: 1) Place the sample to be tested in the sample chamber of the laser sample analysis chamber and bake the sample chamber to a certain vacuum state; 2) Use laser to ablate the sample to be tested, and the released gas passes through a liquid nitrogen bath cold trap to adsorb the active gas; 3) monitoring the total gas pressure and target rare gas of the residual gas after adsorption in step 2) by means of a vacuum gauge and a residual gas analyzer; 4) After the monitoring result in step 3) meets the gas volume required for measurement, a liquid nitrogen bath is used to cool the second cold trap to a certain temperature to adsorb argon gas, while keeping the second cold trap in a liquid nitrogen bath state; 5) After step 4) is completed, the active gas is first removed through the active gas getter 1, and then the gas is purified through the active gas getter 2; 6) After purification, use a liquid nitrogen bath to cool the cold trap 4 to a certain temperature to adsorb Ar, while keeping the cold trap 4 in a liquid nitrogen bath state; 7) Adsorb Ne using ultra-low temperature cold trap device; 8) After step 7) is completed, the gas is introduced into the gas analysis unit for He isotope measurement; 9) After the He isotope measurement is completed, close the gas analysis unit and turn on the ion pump to pump gas; 10) Restore the ultra-low temperature cold trap device to room temperature and turn on the gas analysis unit to measure Ne isotopes 11) After the Ne isotope measurement is completed, close the gas analysis unit and turn on the ion pump to pump gas; 12) Both cold trap 2 and cold trap 4 are restored to liquid nitrogen bath state to room temperature, and cold trap 2 and cold trap 4 are heated to release Ar; 13) Turn on the gas analysis unit to perform Ar isotope measurement.

[0014] Preferably, the baking temperature in step 1) is 120°C and the vacuum state in the sample chamber is 10 -7 mbar; Step 2) The active gas mainly includes: H2, CO, CO2, H2O and hydrocarbon substances; and the laser mainly uses ultraviolet laser; The total gas pressure and target rare gas content in step 3) are detected to reach a certain amount and do not exceed the mass spectrometer detection range.

[0015] Preferably, the liquid nitrogen bath is cooled to -196°C.

[0016] In summary, the present invention has at least the following advantages: The present invention adopts the laser micro-area method to detect the rare gas content of extraterrestrial samples. It mainly uses ultraviolet lasers. The laser beam spot can reach the micron level. Moreover, unlike visible or near-infrared lasers, the absorption of ultraviolet lasers by minerals has nothing to do with the elemental composition of the minerals. The thermal edge effect on adjacent minerals is almost negligible, thus achieving high spatial resolution analysis. The present invention uses laser to perform in-situ ablation of the sample to release the rare gas therein, and quickly and directly analyzes the target area at the micrometer scale, which can not only reduce the amount of sample loss, but also quickly and efficiently perform rare gas isotope analysis on single-particle samples at the micrometer scale, and has the advantages of avoiding the influence of matrix and other interfering phases in the sample, and is suitable for rare gas analysis of extraterrestrial samples; Under the premise of ensuring the measurement accuracy, the estimated amount of rare gas in the sample required by the detection system is approximately 36 Ar~1.2ⅹ10 -11 ccSTP, 20 Ne~3.3ⅹ10 -12 ccSTP; For meteorite samples, for example, Okazaki et al. (2001) reported that individual chondrules in the enstatite chondrite Yamato have high rare gas contents (e.g. 36 Ar can be as high as 7ⅹ10 -6 cm 3 STP / g), the present invention adopts the micro-area in-situ noble gas analysis method, and only 0.02 mg of sample needs to be etched; the present invention can reduce the amount of sample required in terms of the required sample content, and can also efficiently perform noble gas isotope analysis on the sample at the micron scale, which is very suitable for the noble gas analysis of extraterrestrial samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0018] Attached Figure 1 A micro-area in-situ analysis system for rare gases in extraterrestrial samples provided in Example 1 of the present invention.

[0019] exist Figure 1 middle: Among them, Excimer LASER is a laser sample analysis cavity, GAUGE is a vacuum gauge, RGA is a residual gas analyzer, TP is a molecular pump, IP is an ion pump, GT1&2 is an active gas getter one, GT3&4 is an active gas getter two, CT1 is a cold trap one, CT2 is a cold trap two, CT3 is a cold trap three, CT4 is a cold trap four, CRYO is an ultra-low temperature cold trap device, AIR is an atmosphere standard system, STD is a standard gas standard system, LDV is a valve one, PS1V is a valve two, A1V is a valve three, A2V is a valve four, S1V is a valve five, S2V is a valve six, PS2V is a valve seven, IPV is a valve eight, PS3V is a valve nine, CRYOV is a valve ten, and INLETV is a valve eleven. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0021] This embodiment provides a micro-area in-situ analysis system for rare gases in extraterrestrial samples. It includes a gas extraction system, a gas purification unit and a gas analysis unit connected in sequence; The gas extraction system includes a laser sample analysis chamber, a first cold trap and a second cold trap connected in sequence; The gas purification unit comprises a cold trap three, an active gas aspirator and a cold trap four which are connected in sequence; Cold trap two is connected to cold trap three; The cold trap 4 is connected to the gas analysis unit.

[0022] The laser sample analysis cavity is an excimer laser sample analysis cavity, and the excimer laser sample analysis cavity includes a sample chamber and an excimer laser. The excimer laser is mainly an ultraviolet laser, and a REsolution M-50 model can be used. The gas analysis unit is an inert gas mass spectrometer, such as the Helix-MC plus model, which has the ability to test isotopes such as He, Ne, and Ar.

[0023] Preferably, it also includes a residual gas analyzer, a vacuum gauge and a molecular pump, The residual gas analyzer and the vacuum gauge are relatively arranged between the second cold trap and the third cold trap; The molecular pump is connected to the residual gas analyzer.

[0024] The residual gas analyzer is used to monitor the amount of gas removed and the approximate rare gas composition in real time.

[0025] In order to further optimize the above technical solution, the active gas getter device is provided with at least an active gas getter 1 and an active gas getter 2 connected in sequence; The active gas getter one is connected to the cold trap three; The active gas getter 2 is connected to the cold trap 4.

[0026] In order to further optimize the above technical solution, it also includes: an atmospheric standard sample system and a standard gas standard sample system; The atmosphere standard sample system and the standard gas standard sample system are both arranged on the same branch of the main route between the active gas getter 1 and the active gas getter 2; Moreover, the atmosphere standard sample system and the standard gas standard sample system are arranged in parallel.

[0027] In order to further optimize the above technical solution, it also includes: an ultra-low temperature cold trap device and an ion pump; The ultra-low temperature cold trap device and the ion pump are both arranged on different branches of the main route between the cold trap 4 and the gas analysis unit.

[0028] In order to further optimize the above technical solution, it also includes: a plurality of valves, which are arranged on the main road and / or branch road according to the operation requirements.

[0029] In order to further optimize the above technical solution, the valve is provided with at least valve 1 to valve 12; Valve 1 is arranged between cold trap 1 and cold trap 2; Valve 2 is arranged between cold trap 3 and active gas getter 1; Valve 3 and valve 4 are sequentially arranged at the front end of the atmospheric standard sample system; Valve five and valve six are sequentially arranged at the front end of the standard gas sample system; Valve seven is arranged between active gas getter one and active gas getter two; Valve 8 is arranged at the front end of the ion pump; Valve nine and valve ten are arranged in sequence at the front end of the ultra-low temperature cold trap device, and valve nine is arranged at the rear end of cold trap four; The valve eleven is arranged at the front end of the gas analysis unit. Example 2

[0030] This embodiment provides a micro-area in-situ analysis method for rare gases in extraterrestrial samples, using an analysis system to analyze the rare gases in extraterrestrial samples, specifically comprising the following steps: The sample to be tested is placed in the sample chamber of the laser sample analysis chamber, and the sample chamber is baked to reach a certain vacuum state; The sample chamber is baked at 120°C through a heating belt and a heating base, and the vacuum state reaches 10 -7 mbar; Close valve 2, use laser to ablate the sample to be tested, and the released gas passes through liquid nitrogen bath cold trap 1 to adsorb active gas; The adsorbed gases are mainly H2, CO, CO2, H2O, hydrocarbons, etc. The total gas pressure and target rare gas of the residual gas after adsorption in step 2) are monitored by a vacuum gauge and a residual gas analyzer; In step 3), after the monitoring result meets the gas volume required for measurement, a liquid nitrogen bath is used to cool the second cold trap to -196°C to adsorb Ar gas for 20 minutes, while keeping the second cold trap in a liquid nitrogen bath state; Step 4) After the operation is completed, close valve seven, open valve two and first pass through active gas getter one to remove active gas; close valve eight and valve nine, open valve seven, and then purify the gas through active gas getter two for 10 minutes; After purification, a liquid nitrogen bath was used to cool the cold trap 4 to -196°C to adsorb Ar, while keeping the cold trap 4 in a liquid nitrogen bath state; Valve 11 is kept closed, valves 9 and 10 are opened, and Ne gas is adsorbed at -30K for 20 min using an ultra-low temperature cold trap device, and then valve 10 is closed; After step 7) is completed, valve 11 is opened and the gas is introduced into the gas analysis unit for He isotope measurement; After the He isotope measurement is completed, close valve 11, open valve 8 to pump air for 20 minutes, and then close valves 8 and 9; Restore the ultra-low temperature cold trap device to room temperature for 10 minutes, open valve 10 and valve 11, and conduct Ne isotope measurement in the gas analysis unit; After the Ne isotope measurement is completed, close valve 10 and valve 11, open valve 8 and valve 9 to pump air for 20 minutes, and close valve 8; Cold trap 2 and cold trap 4 were restored to liquid nitrogen bath state to room temperature, and cold trap 2 and cold trap 4 were heated to release Ar for 10 min; Open valve 11 and the gas analysis unit performs Ar isotope measurement.

[0031] In step 3), the total gas pressure and target rare gas content are detected to reach a certain amount and do not exceed the mass spectrometer detection range.

[0032] Each embodiment of this specification focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referenced to each other.

[0033] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A micro-area in-situ analysis system for rare gases in extraterrestrial samples, characterized in that: It includes a gas extraction system, a gas purification unit and a gas analysis unit connected in sequence; Wherein, the gas extraction system comprises a laser sample analysis chamber, a cold trap 1 and a cold trap 2 which are connected in sequence; The gas purification unit comprises a cold trap three, an active gas aspirator and a cold trap four which are connected in sequence; The second cold trap is connected to the third cold trap; The cold trap four is connected to the gas analysis unit; The laser sample analysis cavity comprises a sample chamber and an excimer laser.

2. The micro-area in-situ analysis system for rare gases in extraterrestrial samples according to claim 1, characterized in that: Also includes residual gas analyzer, vacuum gauge and molecular pump, The residual gas analyzer and the vacuum gauge are relatively arranged between the second cold trap and the third cold trap; The molecular pump is connected to the residual gas analyzer.

3. The micro-area in-situ analysis system for rare gases in extraterrestrial samples according to claim 2, characterized in that: The active gas getter device is provided with at least an active gas getter 1 and an active gas getter 2 connected in sequence; The active gas getter 1 is connected to the cold trap 3; The active gas getter 2 is connected to the cold trap 4.

4. The micro-area in-situ analysis system for rare gases in extraterrestrial samples according to claim 3, characterized in that: Also includes: Atmospheric standard sample system and standard gas standard sample system; The atmospheric standard sample system and the standard gas standard sample system are both arranged on the same branch of the main path between the active gas getter 1 and the active gas getter 2; Furthermore, the atmosphere standard sample system and the standard gas standard sample system are arranged in parallel.

5. The micro-area in-situ analysis system for rare gases in extraterrestrial samples according to claim 1, characterized in that: Also includes: Ultra-low temperature cold trap device and ion pump; The ultra-low temperature cold trap device and the ion pump are both arranged on different branches of the main path between the cold trap 4 and the gas analysis unit.

6. The micro-area in-situ analysis system for rare gases in extraterrestrial samples according to any one of claims 1 to 5, characterized in that: Also includes: A plurality of valves are arranged on the main line and / or the branch line according to the operation requirements.

7. The micro-area in-situ analysis system for rare gases in extraterrestrial samples according to claim 6, characterized in that: The valve is at least provided with valve 1 to valve 12; The valve 1 is arranged between the cold trap 1 and the cold trap 2; The valve 2 is arranged between the cold trap 3 and the active gas getter 1; The valve three and the valve four are sequentially arranged at the front end of the atmospheric standard sample system; The valve five and the valve six are sequentially arranged at the front end of the standard gas standard sample system; The valve seven is arranged between the active gas getter one and the active gas getter two; The valve 8 is arranged at the front end of the ion pump; The valve nine and the valve ten are arranged in sequence at the front end of the ultra-low temperature cold trap device, and the valve nine is arranged at the rear end of the cold trap four; The valve eleven is arranged at the front end of the gas analysis unit.

8. A method for in-situ analysis of rare gases in extraterrestrial samples in micro-areas, characterized in that: Analyzing the noble gases in extraterrestrial samples using the analysis system described in claim 7 specifically comprises the following steps: The sample to be tested is placed in the sample chamber of the laser sample analysis chamber, and the sample chamber is baked to reach a certain vacuum state; Laser is used to ablate the sample to be tested, and the released gas passes through a liquid nitrogen bath cold trap to adsorb the active gas; The total gas pressure and target rare gas of the residual gas after adsorption in step 2) are monitored by a vacuum gauge and a residual gas analyzer; In step 3), after the monitoring result meets the gas volume required for measurement, a liquid nitrogen bath is used to cool the second cold trap to a certain temperature to adsorb argon gas, while keeping the second cold trap in a liquid nitrogen bath state; Step 4) After the operation is completed, the active gas is first removed through the active gas getter 1, and then the gas is purified through the active gas getter 2; After purification, a liquid nitrogen bath is used to cool the cold trap 4 to a certain temperature to adsorb Ar, while keeping the cold trap 4 in a liquid nitrogen bath state; Adsorb Ne using ultra-low temperature cold trap device; Step 7) After completion, the gas is introduced into the gas analysis unit for He isotope measurement; After the He isotope measurement is completed, the gas analysis unit is turned off and the ion pump is turned on to extract gas; Restore the ultra-low temperature cold trap device to room temperature and turn on the gas analysis unit to measure Ne isotopes; After the Ne isotope measurement is completed, the gas analysis unit is turned off and the ion pump is turned on to extract gas; Cold trap 2 and cold trap 4 are both restored to liquid nitrogen bath state to room temperature, and cold trap 2 and cold trap 4 are heated to release Ar; Turn on the gas analysis unit to perform Ar isotope measurement.

9. The micro-area in-situ analysis method of noble gases in extraterrestrial samples according to claim 8, characterized in that: Step 1) The baking temperature is 120°C and the vacuum state in the sample chamber is 10 -7 mbar; Step 2) The active gases mainly include: H2, N2, CO, CO2, H2O; and the laser mainly includes ultraviolet laser.

10. The micro-area in-situ analysis method of noble gases in extraterrestrial samples according to claim 9, characterized in that: The liquid nitrogen bath was cooled to -196°C.

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