A small-volume ablation cell with multi-target co-located laser ablation and its working method

Abstract

The present invention relates to the technical field of chemical analysis equipment, and specifically discloses a small-volume ablation cell and a working method for laser ablation of multiple targets at the same position, comprising an ablation chamber, a sample chamber and a laser system. The ablation chamber comprises an ablation cover, a sealing chamber and a sealing partition. The sealing chamber adopts a spindle column structure and is fixed inside the ablation cover. A sealing partition is provided at the bottom of the ablation chamber, and a sample hole is provided in the middle of the sealing partition for the sample to enter the sealed chamber. The sample chamber is provided with a sample chamber shell, a rotating sample target holder and multiple sample targets. A slot is provided at the top of the sample chamber shell, and the sample chamber shell is connected to the bottom of the ablation cover through the slot. The sample is placed on the sample target, and the sample target is installed on the rotating sample target holder, which is used to rotate the sample target holder to push the sample on the sample target into the sample hole. The sample targets designed by the present invention are at the same position in the ablation chamber, so that the particle transmission efficiency is basically the same, thereby reducing the influence of the position effect on the accuracy and precision of the isotope composition determination result.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical analysis equipment, and in particular to a small-volume ablation cell for laser ablation of multiple targets at the same position and a working method thereof. Background Art

[0002] The design of the ablation cell has a direct impact on aerosol transport and analytical results. Typically, laser energy is focused onto the sample surface through a window transparent to the wavelength being used, ablating the selected area. A carrier gas is then introduced to transport the ablation-generated aerosol to the LA-MC-ICPMS. A good laser ablation cell should possess efficient sample aerosol transport, no position effects, low memory effects, and ease of operation.

[0003] Many outstanding scholars at home and abroad have developed ablation cells of varying volumes, geometries, and materials for various applications. Ablation cells with different design concepts play an important role in diverse research fields and for different sample types. Extensive preliminary research on ablation cells has shown that the final amount of effective aerosol entering the plasma is independent of the tube diameter and geometric design of the transmission path. The total effective aerosol volume is a function of the ablation cell volume. In contrast, small-volume ablation cells offer high sensitivity and minimal position effects, reducing laser sweep time but reducing sample capacity. Large-volume ablation cells can accommodate a large number of samples, but suffer from significant memory and position effects.

[0004] Due to its exceptional elemental detection capabilities, ICP-MS has become a key instrument in analytical chemistry and geochemistry. Its application is increasingly widespread in fields such as environment, geology, medicine, and agriculture. Due to the demands of scientific research and the superior analytical capabilities of ICP-MS, the technology for in-situ microanalysis of samples is becoming increasingly mature. Instruments currently suitable for in-situ microanalysis include electron microprobes, secondary particle microprobes, and laser ablation plasma mass spectrometry.

[0005] Laser ablation-ICP-MS is an accurate and precise technique for the in situ analysis of trace elements in solids, including natural and artificial silicates, carbonates, oxides, and sulfides. Laser ablation involves focusing laser light onto the sample surface through a laser beam path. Aerosol particles generated by the ablation are then transported via a carrier gas to an inductively coupled plasma mass spectrometer for elemental and isotopic analysis. After ionization by the plasma torch, the amount of analyte ultimately entering the MS mass analyzer is less than 1% of the total aerosol volume. To improve the sensitivity and precision of La-ICPMS analysis, previous research has focused on modifying the laser wavelength (1064 nm, 532 nm, 266 nm, 248 nm, 222 nm, 213 nm, 193 nm, and 157 nm), changing the ablation cell geometry, adding smoothing devices to the aerosol line, and changing the geometry of the sample cone (S-cone and Jet cone) and the skimmer cone (X-cone and H-cone). These improvements have significantly improved instrument performance. However, these ablation cells all have position effects due to the different positions of the sample targets in the ablation cells, which affects the accuracy and precision of the analysis results.

[0006] Currently, labs commonly use plasticine to fill ablation cells instead of target holders. However, this method is inconvenient and inefficient for sample exchange, has an uneven surface, and is prone to vortex formation. Furthermore, the plasticine can introduce background contamination, which can seriously affect analytical results. Therefore, there is an urgent need to design a small-volume ablation cell and operating method for co-location laser ablation of multiple targets. This ablation cell, which reduces the effect of sample and target position within the ablation cell, is of great significance for high-precision isotopic composition measurements using laser ablation multi-collector inductively coupled plasma-mass spectrometry. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention aims to provide a small-volume ablation cell and a working method for laser ablation of multiple targets at the same position.

[0008] The technical solution adopted by the present invention to solve the technical problem is: a small-volume ablation cell for laser ablation of multiple targets at the same position, comprising an ablation chamber, a sample chamber and a laser system. The ablation chamber comprises an ablation cover, a sealing chamber and a sealing partition. The sealing chamber adopts a spindle-shaped column structure and is fixed inside the ablation cover. The sealing partition is provided at the bottom of the ablation chamber, and a sample hole is provided in the middle of the sealing partition for the sample to enter the sealed chamber.

[0009] The sample chamber is provided with a sample chamber shell, a rotating sample target bracket and multiple sample targets. A slot is provided on the top of the sample chamber shell. The sample chamber shell is connected to the bottom of the erosion cover through the slot. The sample is placed on the sample target. The sample target is installed on the rotating sample target bracket, which is used to rotate the sample target bracket to push the sample on the sample target into the sample hole.

[0010] Specifically, the sealing partitions are two pieces arranged opposite to each other, and the sealing partitions are made of transparent soft elastic material. The opposite sides of the sealing partitions are provided with matching semicircular hole structures, and the semicircular hole structures of the two sealing partitions are used to form sample holes relative to each other. The rear of the sealing partition is fixed on the sealing fixing plate, and the sealing fixing plate is fixed on the bottom of the erosion cover to form a sealing base of the erosion cover.

[0011] Specifically, electromagnets and / or magnetic blocks are provided on both side plates of the semicircular hole structure of the sealing partition. The electromagnet and the magnetic block are arranged opposite to each other on the two sealing partitions, and are used to attract the magnetic block to seal the sample target in the sample hole when the electromagnet is energized. The electromagnet is connected to a power switch, and the power switch controls the on and off of the electromagnet.

[0012] Specifically, an observation window is provided on the top of the sealed chamber, and CaF glass is installed in the observation window. The observation window, sample hole and sample target are concentric. The laser beam of the laser system is irradiated on the sample through the observation window. The laser beam is emitted by a laser emitter provided in the laser system.

[0013] Specifically, the openings at both ends of the shuttle column structure of the sealed chamber are respectively the carrier gas inlet and the carrier gas outlet. The carrier gas inlet is located at the upper part of one side of the sealed chamber, and the carrier gas outlet is located at the lower part of one side of the sealed chamber, which is used to control the inlet and outlet of the carrier gas. The carrier gas is argon.

[0014] Specifically, a support frame is provided in the sample chamber shell, a motor is installed on the support frame, a rotating bearing is installed on the motor shaft of the motor, a rotating sample target bracket is installed on the rotating bearing, and a sample target is provided on the rotating sample target bracket for the motor to drive the sample target to rotate.

[0015] Specifically, an angle sensor is installed on the motor shaft of the motor, the angle sensor is electrically connected to a controller, the controller is installed outside the sample chamber housing, and the controller is electrically connected to a control switch for controlling the rotation angle of the motor shaft.

[0016] A method for operating a small-volume ablation cell for co-location laser ablation of multiple targets comprises the following steps:

[0017] 1) Mark the test point on the sample to be tested. Stick the bottom of the sample to be tested on the sample target with the marked position facing upwards. Press the control switch controller to control the motor shaft to rotate a certain angle, and stick another sample to be tested on the next sample target. Repeat the operation to fix the sample to be tested on different sample targets in turn.

[0018] 2) The ablation chamber is installed in the groove of the sample chamber housing. The sample on the sample target in the sample hole enters the sealed chamber. The electromagnet is energized to attract the magnetic block, so that the soft sealing partition seals the sample target, and the sealed chamber forms a closed space.

[0019] 3) Turn on the laser emitter, allowing the laser beam to enter the sealed chamber through the observation window and hit the sample, generating aerosol particles. At the same time, argon gas enters through the carrier gas inlet and is transported through the carrier gas outlet to the LA-MC-ICPMS instrument for sample plasma mass spectrometry elemental and isotope analysis;

[0020] 4) After the sample analysis is completed, the laser beam and carrier gas are turned off, the electromagnet is powered off, the sample target is unsealed, and the control switch is pressed. The controller controls the motor to drive the rotating sample target holder to rotate a certain angle. The next sample target presses the soft sealing partition so that the sample target is located in the sample hole. The sample on the sample target enters the sealing chamber, and then the electromagnet is powered on to seal the sample target;

[0021] 5) Repeat steps 3)-4) to perform plasma mass spectrometry element and isotope analysis on the sample on each target.

[0022] The present invention has the following beneficial effects:

[0023] The small-volume ablation cell and working method for laser ablation of multiple targets at the same position designed by the present invention adopt a rotatable sample target position, and the sample is fixed on the sample target position. Each rotation has a target at the position to be tested, and the sealing partition seals the sample to be tested in the ablation chamber. At this time, the upper ablation chamber is the same as the traditional ablation cell, overcoming the problem that the existing sample chamber places multiple sample targets to produce position effects, and frequent sample changes easily affect the accuracy of sample analysis. In addition, the ablation sealing chamber is changed from the traditional circular shape to the shuttle shape, and the carrier gas inlet and carrier gas outlet are distributed at both ends of the shuttle structure. No vortex airflow is generated during the aerosol transmission process, so the position effect in the ablation chamber is minimized, and the accuracy and precision of the analysis results are improved; the designed sample targets are at the same position in the ablation chamber, so that the particle transmission efficiency is basically the same, thereby reducing the influence of the position effect on the accuracy and precision of the isotope composition determination results. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the overall structure of a small-volume ablation cell for laser ablation of multiple targets at the same position.

[0025] Figure 2 yes Figure 1 Top view of .

[0026] Figure 3 It is a structural diagram of the sealing partition.

[0027] Figure 4 It is a structural diagram of the motor transmission mechanism.

[0028] In the figure: 1-erosion chamber; 2-sample chamber; 3-laser system; 1.1-erosion cover; 1.2-sealing partition; 1.3-sample hole; 1.4-electromagnet; 1.5-magnetic block; 1.6-observation window; 1.7-carrier gas inlet; 1.8-carrier gas outlet; 1.9-sealing fixing plate; 1.10-sealing chamber; 2.1-sample target; 2.2-rotating sample target bracket; 2.3-sample chamber housing; 2.4-rotating bearing; 2.5-motor; 2.6-angle sensor; 2.7-support frame; 3.1-laser emitter; 3.2-laser beam. DETAILED DESCRIPTION

[0029] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely further describe the technical solutions in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] like Figure 1-4 As shown, a small-volume ablation cell for laser ablation of multiple targets at the same position includes an ablation chamber 1, a sample chamber 2 and a laser system 3. The laser system 3 includes a laser emitter 3.1 and a laser beam 3.2. The laser emitter 3.1 emits a laser beam 3.2 to irradiate the sample.

[0031] The erosion chamber 1 includes an erosion cover 1.1, a sealing chamber 1.10, a sealing partition 1.2, a sample hole 1.3, an electromagnet 1.4, a magnetic block 1.5, an observation window 1.6, a carrier gas inlet 1.7, a carrier gas outlet 1.8 and a sealing fixing plate 1.9. The sealed chamber 1 adopts a spindle column structure, and the sealed chamber 1.10 is fixed inside the erosion cover 1.1. A sealing partition 1.2 is provided at the bottom of the erosion chamber 1, and a sample hole 1.3 is provided in the middle of the sealing partition 1.2 for the sample to enter the sealed chamber 1.10.

[0032] An observation window 1.6 is provided at the top of the sealed chamber 1. CaF glass is installed in the observation window 1.6. The observation window 1.6, the sample hole 1.3 and the sample target 2.1 are concentric. The laser beam 3.2 of the laser system 3 is irradiated on the sample through the observation window 1.6, so that the sample target 2.1 is at the same position in the ablation chamber 1, so that the particle transmission efficiency is basically the same, thereby reducing the influence of the position effect on the accuracy and precision of the isotope composition results.

[0033] The openings at both ends of the spindle column structure of the sealed chamber 1 are respectively the carrier gas inlet 1.7 and the carrier gas outlet 1.8. The carrier gas inlet 1.7 is located at the upper part of one side of the sealed chamber 1, and the carrier gas outlet 1.8 is located at the lower part of one side of the sealed chamber 1, which is used to control the inlet and outlet of the carrier gas. The carrier gas uses argon, and the carrier gas is introduced to transport the aerosol generated by erosion to the analytical instrument.

[0034] Two sealing baffles 1.2 are arranged opposite each other. Sealing baffles 1.2 are made of a transparent, soft, elastic material. Matching semicircular hole structures are provided on opposite sides of sealing baffles 1.2. The semicircular hole structures of the two sealing baffles 1.2 are used to form sample wells 1.3. The rear portions of sealing baffles 1.2 are fixed to sealing fixing plates 1.9. Sealing fixing plates 1.9 are fixed to the bottom of erosion cover 1.1 to form a sealed base for erosion cover 1.1. Electromagnets 1.4 and / or magnetic blocks 1.5 are provided on both side panels of the semicircular hole structures of sealing baffles 1.2. Electromagnets 1.4 and magnetic blocks 1.5 are arranged opposite each other on the two sealing baffles 1.2. When electromagnet 1.4 is energized, magnetic blocks 1.5 engage and seal sample targets 2.1 within sample wells 1.3. Electromagnet 1.4 is connected to a power switch, which controls the on and off of electromagnet 1.4.

[0035] The sample chamber 2 includes a sample chamber shell 2.3, a rotating sample target bracket 2.2, a motor 2.5, a rotating bearing 2.4, an angle sensor 2.6, a support frame 2.7 and 6 sample targets. A slot is provided on the top of the sample chamber shell 2.3, and the sample chamber shell 2.3 is connected to the bottom of the erosion cover 1.1 through the slot, so that the erosion chamber 1 and the sample chamber 2 form a detachable upper and lower structure, which is more compact and convenient, and easy to install and use.

[0036] A support frame 2.7 is mounted within the sample chamber housing 2.3. A motor 2.5 is mounted on the support frame 2.7. A rotary bearing 2.4 is mounted on the motor shaft of the motor 2.5. A rotating sample target holder 2.2 is mounted on the rotating sample target holder 2.2. The rotating sample target holder 2.2 is provided with a sample target 2.1, which is driven by the motor 2.5 to rotate. A sample is placed on the sample target 2.1, which is mounted on the rotating sample target holder 2.2. The rotating sample target holder 2.2 has six struts, one end of which is connected to the sample target 2.1 and the other end to the rotary bearing 2.4. This allows the rotating sample target holder 2.2 to push the sample on the sample target 2.1 into the sample well 1.3.

[0037] An angle sensor 2.6 is installed on the motor shaft of the motor 2.5. The angle sensor 2.6 is electrically connected to a controller. The controller is installed outside the sample chamber housing 2.3 and is electrically connected to a control switch. When the control switch is pressed, the controller controls the motor shaft to rotate 60 degrees each time.

[0038] An embodiment of the present invention:

[0039] The sealed chamber 1.10 inside the erosion chamber 1 is in the shape of a flat spindle-shaped column. The upper surface of the spindle-shaped column is a CaF glass circular observation window 1.6. The middle width of the spindle-shaped column is 3 cm, the length is 6.7 cm, and the height is 2.1 cm. The air inlet and outlet are located at both ends of the spindle-shaped column.

[0040] The elastic material of the sealing partition 1.2 is transparent. The two parts of the sealing partition 1.2 are integrally formed. The main body of the sealing partition 1.2 is formed by pouring the elastic material. The surface of the sealing partition 1.2 main body is flat. A sample hole 1.3 is opened in the center of the sealing partition 1.2. The inner diameter of the sample hole 1.3 can be increased by extrusion, thereby making the inner diameter of the sample hole 1.3 variable, and can accommodate samples with a diameter deviation within ±2mm (the diameter of the sample target 2.1 is generally 2.5cm).

[0041] The sample chamber 2 has a semi-elliptical side, an inner diameter of 6.7 cm, and an inner maximum thickness of 2.8 cm. The rotating sample target holder 2.2 has six sample target positions, which are evenly distributed at an angle of 60 degrees.

[0042] A method for operating a small-volume ablation cell for co-location laser ablation of multiple targets comprises the following steps:

[0043] 1) Mark the test point on the sample to be tested. Stick the bottom of the sample to be tested on the sample target 2.1 with the marked position facing upwards. Press the control switch controller to control the motor shaft to rotate 60 degrees, and stick another sample to be tested on the next sample target 2.1. Repeat the operation to fix the sample to be tested on the other four sample targets 2.1 in turn;

[0044] 2) The ablation chamber 1 is installed in the groove of the sample chamber housing 2.3. The sample on the sample target 2.1 in the sample hole 1.3 enters the sealed chamber 1.10. The electromagnet 1.4 is energized to attract the magnetic block 1.5, causing the soft sealing diaphragm 1.2 to seal the sample target 2.1, and the sealed chamber 1.10 forms a closed space.

[0045] 3) Turn on laser emitter 3.1, allowing laser beam 3.2 to enter sealed chamber 1.10 through observation window 1.6 and strike the sample, generating aerosol particles. Simultaneously, argon gas enters through carrier gas inlet 1.7 and is delivered through carrier gas outlet 1.8 to the LA-MC-ICPMS instrument for elemental and isotopic analysis of the sample by plasma mass spectrometry.

[0046] 4) After sample analysis is complete, the laser beam 3.2 and carrier gas are turned off, the electromagnet 1.4 is de-energized, the sample target 2.1 is unsealed, and the control switch is pressed. The controller controls the motor 2.5 to rotate the rotating sample target holder 2.2 60 degrees. The lower sample target 2.1 presses against the soft sealing diaphragm 1.2, positioning the sample target 2.1 within the sample hole 1.3. The sample on the sample target 2.1 enters the sealing chamber 1.10, and the electromagnet 1.4 is then energized to seal the sample target 2.1.

[0047] 5) Repeat steps 3)-4) to perform plasma mass spectrometry element and isotope analysis on each sample on target 2.1.

[0048] The present invention is not limited to the above-mentioned embodiments. Anyone should be aware that any structural changes made under the guidance of the present invention, and any technical solutions that are the same or similar to those of the present invention, fall within the scope of protection of the present invention.

[0049] The technology, shape, and structure not described in detail in the present invention are all well-known technologies.

Claims

1. A small-volume ablation cell for laser ablation of multiple targets at the same location, characterized in that: The apparatus comprises an ablation chamber, a sample chamber and a laser system. The ablation chamber comprises an ablation housing, a sealing chamber and a sealing partition. The sealing chamber adopts a spindle-shaped column structure and is fixed inside the ablation housing. A sealing partition is provided at the bottom of the ablation chamber, and a sample hole is provided in the middle of the sealing partition for the sample to enter the sealed chamber. The sealing partitions are arranged opposite to each other in two pieces and are made of a transparent soft elastic material. The opposite sides of the sealing partitions are provided with matching semicircular hole structures, and the semicircular hole structures of the two sealing partitions are used to form a sample hole relative to each other. The rear part of the sealing partition is fixed to a sealing fixing plate, and the sealing fixing plate is fixed to the bottom of the ablation housing to form a sealing base of the ablation housing. The sample chamber is provided with a sample chamber shell, a rotating sample target holder and multiple sample targets. A slot is provided on the top of the sample chamber shell, and the sample chamber shell is connected to the bottom of the erosion cover through the slot. The sample is placed on the sample target, and the sample target is installed on the rotating sample target holder, which is used to rotate the sample target holder to push the sample on the sample target into the sample hole. A support frame is provided in the sample chamber shell, and a motor is installed on the support frame. A rotating bearing is installed on the motor shaft of the motor, and a rotating sample target holder is installed on the rotating bearing. The rotating sample target holder is provided with a sample target, and the motor drives the sample target to rotate.

2. The small-volume ablation cell for multi-target co-location laser ablation according to claim 1, characterized in that: Electromagnets and / or magnetic blocks are provided on both side plates of the semicircular hole structure of the sealing partition. The electromagnet and the magnetic block are arranged opposite to each other on the two sealing partitions, and are used to attract the magnetic block to seal the sample target in the sample hole when the electromagnet is energized. The electromagnet is connected to a power switch, and the power switch controls the on and off of the electromagnet.

3. The small-volume ablation cell for multi-target co-location laser ablation according to claim 1, characterized in that: An observation window is provided on the top of the sealed chamber, in which CaF glass is installed. The observation window, the sample hole and the sample target are concentric. The laser beam of the laser system is irradiated on the sample through the observation window. The laser beam is emitted by a laser emitter provided in the laser system.

4. The small-volume ablation cell for multi-target co-location laser ablation according to claim 1, characterized in that: The two end openings of the shuttle column structure of the sealed chamber are respectively a carrier gas inlet and a carrier gas outlet. The carrier gas inlet is located at the upper part of one side of the sealed chamber, and the carrier gas outlet is located at the lower part of one side of the sealed chamber, which is used to control the inlet and outlet of the carrier gas. The carrier gas is argon.

5. The small-volume ablation cell for multi-target co-location laser ablation according to claim 1, characterized in that: An angle sensor is installed on the motor shaft of the motor, and the angle sensor is electrically connected to a controller. The controller is installed outside the sample chamber housing and is electrically connected to a control switch for controlling the rotation angle of the motor shaft.

6. The method for operating a small-volume ablation cell for co-location laser ablation of multiple targets according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) Mark the test point on the sample to be tested. Stick the bottom of the sample to be tested on the sample target with the marked position facing upwards. Press the control switch controller to control the motor shaft to rotate a certain angle, and stick another sample to be tested on the next sample target. Repeat the operation to fix the sample to be tested on different sample targets in turn. 2) The ablation chamber is installed in the groove of the sample chamber housing. The sample on the sample target in the sample hole enters the sealed chamber. The electromagnet is energized to attract the magnetic block, so that the soft sealing partition seals the sample target, and the sealed chamber forms a closed space. 3) Turn on the laser emitter, allowing the laser beam to enter the sealed chamber through the observation window and hit the sample, generating aerosol particles. At the same time, argon gas enters through the carrier gas inlet and is transported through the carrier gas outlet to the LA-MC-ICPMS instrument for sample plasma mass spectrometry elemental and isotope analysis; 4) After the sample analysis is completed, the laser beam and carrier gas are turned off, the electromagnet is powered off, the sample target is unsealed, and the control switch is pressed. The controller controls the motor to drive the rotating sample target holder to rotate a certain angle. The next sample target presses the soft sealing partition so that the sample target is located in the sample hole. The sample on the sample target enters the sealing chamber, and then the electromagnet is powered on to seal the sample target; 5) Repeat steps 3)-4) to perform plasma mass spectrometry element and isotope analysis on the sample on each target.

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