Preparation method and application of secondary ion mass spectrometry sample for analyzing porous material

Abstract

The invention provides a sample preparation method for secondary ion mass spectrometry analysis of a porous material and application of the sample preparation method, the sample preparation method comprises the following steps: preparing a to-be-tested sample into sheet-shaped samples, then taking two sheet-shaped samples, enabling to-be-tested surfaces of the two sheet-shaped samples to be in opposite contact, applying pressure, maintaining pressure, releasing pressure, and then selecting one sheet as a test sample; and placing the hollow metal sheet at the hollow part of the secondary ion mass spectrometry sample table, placing the to-be-tested surface of the test sample facing the hollow metal sheet, and flattening the to-be-tested surface of the test sample to complete the preparation of the sample. The method provided by the invention does not destroy the surface pore structure of the porous material, can obviously improve the secondary ion mass spectrum signal of the porous material, obviously improves the detection repeatability, can repeat the mass spectrum signal after multiple tests, and is beneficial to the secondary ion mass spectrum analysis of the porous material.

Description

Technical Field

[0001] This invention belongs to the field of secondary ion mass spectrometry detection technology, specifically relating to a sample preparation method for secondary ion mass spectrometry analysis of porous materials and its application. Background Technology

[0002] Secondary ion mass spectrometry (SIMS) analysis of porous materials often presents various challenges due to their unique physical structure, characterized by high porosity, large specific surface area, and low density. SIMS testing requires an atomically flat surface, but porous materials exhibit significant height differences and suspended structures, making secondary ion yields highly susceptible to surface morphology. Furthermore, the low-density pore structure means that signals from lower layers are also detected when measuring surface mass spectrometry signals, further leading to poor repeatability and interpretability of the collected mass spectrometry signals. A common approach for analyzing such samples is to fix a small sample (e.g., 5×5mm) onto conductive tape before testing. However, experiments have shown that when the selected film thickness is too thick (greater than 2mm), the sample conductivity is very poor, making it impossible to obtain a valid secondary ion mass spectrometry signal. Reducing the sample thickness, for example to less than 1mm, further complicates sample preparation and results in low success rates. When a thin sheet less than 1 mm thick is fixed on conductive tape, although a mass spectrometry signal can be measured, double peaks / abnormal peaks still appear, and the repeatability is poor, that is, the mass spectrometry signal is not repeated after multiple tests, and the secondary ion mass spectrometry signal of the porous material itself cannot be obtained.

[0003] CN112229699A discloses a sample preparation method for dynamic secondary ion mass spectrometry (D-SIMS) analysis, particularly suitable for samples with a test surface side length not exceeding 200 μm. The preparation method is as follows: Adhesive tape is attached to a flat carrier; a mold is opened at both ends, and the mold material at one open end is folded and attached to the adhesive tape. The sample to be tested and the molding material are placed through the other open end, with the test surface of the sample adhering to the adhesive tape, thus obtaining the carrier material; the carrier material is heated to a temperature not lower than the melting point of the molding material; after the molding material melts, the height of the liquid molding material is higher than the height of the sample to be tested. After heating, it is compacted, and the mold is removed; the carrier and adhesive tape are removed, and the sample to be tested is embedded in the molding material, completing the sample preparation. This method has a high sample preparation success rate, and the accuracy and precision of the analysis are greatly improved, overcoming the problems of inaccurate D-SIMS analysis results and easy introduction of contamination in previous sample preparation methods. However, it is still a tape-based sample preparation method, which is difficult to apply to the detection of porous materials.

[0004] Therefore, how to provide a sample preparation method that can be used for secondary ion mass spectrometry analysis of porous materials has become an urgent problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a sample preparation method for secondary ion mass spectrometry analysis of porous materials and its application. The method provided by this invention does not damage the pore structure of the porous material surface, significantly improves the secondary ion mass spectrometry signal of the porous material, and significantly enhances detection repeatability. Multiple tests yield reproducible mass spectrometry signals, which is beneficial for the secondary ion mass spectrometry analysis of this type of porous material.

[0006] To achieve this objective, the present invention employs the following technical solution:

[0007] On one hand, the present invention provides a sample preparation method for secondary ion mass spectrometry analysis of porous materials, the sample preparation method comprising the following steps:

[0008] The sample to be tested is prepared into a sheet sample. Then, two sheet samples are taken, their test surfaces are brought into contact and pressure is applied and maintained. After the pressure is released, one of the sheets is randomly selected as the test sample.

[0009] Place the test surface of the sample onto the cutout area of ​​the secondary ion mass spectrometry sample stage and flatten it to complete the sample preparation.

[0010] The above method utilizes the "mirror contact compression method," which involves placing the test surfaces of two samples in relative contact to form a "mirror contact" structure for pressure application. This method effectively compacts the sample without damaging the pore structure on the surface of the porous material, avoiding interference from the lower layer of the porous material. Furthermore, the contact between the test surfaces prevents the introduction of additional contamination, significantly improving the secondary ion mass spectrometry signal of the porous material. It also significantly enhances detection repeatability, allowing for reproducible mass spectrometry signals from multiple tests, which is beneficial for the secondary ion mass spectrometry analysis of this type of porous material.

[0011] Preferably, the thickness of the sheet sample is 0.5-1 cm, such as 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm or 1 cm, but is not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0012] Preferably, the size of the sheet-like sample does not exceed 1cm × 1cm.

[0013] Preferably, the applied pressure is 10-30 MPa, such as 10 MPa, 15 MPa, 20 MPa, 25 MPa or 30 MPa, but not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0014] Preferably, the pressurization process is a uniform pressurization.

[0015] Preferably, the pressure holding time is 0.5-2 min, such as 0.5 min, 0.6 min, 0.7 min, 0.8 min, 0.9 min, 1 min, 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min, 1.9 min, or 2 min, but is not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0016] The above-mentioned pressure application and holding process can effectively ensure that the test surface of the sample is flat, the pore structure is not damaged, the surface density is increased and it is more compact, thereby effectively improving the repeatability of the test.

[0017] Preferably, the thickness of the test sample is not higher than 1 mm, such as 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm, but is not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0018] Preferably, the thickness of the test sample is 0.2-0.8 mm.

[0019] Preferably, all instruments and tools used in the sample preparation method have been cleaned.

[0020] On the other hand, the present invention also provides the application of the sample preparation method described above in secondary ion mass spectrometry analysis of porous materials.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention provides a sample preparation method for secondary ion mass spectrometry analysis of porous materials. Utilizing a "mirror contact compression method," two samples are placed face-to-face to form a "mirror contact" structure for compression. This method effectively compacts the sample without damaging the surface pore structure of the porous material, avoiding interference from signals in the lower layers of the porous material. Furthermore, the mutual contact between the sample surfaces prevents the introduction of additional contamination, significantly improving the secondary ion mass spectrometry signal of the porous material and enhancing detection repeatability. Multiple tests yield reproducible mass spectrometry signals, which is beneficial for the secondary ion mass spectrometry analysis of this type of porous material. Attached Figure Description

[0023] Figure 1 These are schematic diagrams of the sample sheets in Examples 1-5;

[0024] Figure 2 These are schematic diagrams of the mirror contact pressing method in Examples 1-5;

[0025] Figure 3 These are schematic diagrams of the structures of the samples after compression in Examples 1-5;

[0026] Figure 4 These are secondary ion mass spectra at different positions in the sample obtained in Example 1;

[0027] Figure 5 This is a comparison of the secondary ion mass spectra of the samples obtained in Example 1 and Comparative Example 1. Detailed Implementation

[0028] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0029] All instruments and tools used in the following methods have been cleaned.

[0030] Example 1

[0031] This embodiment provides a sample preparation method for secondary ion mass spectrometry analysis of porous materials, the specific steps of which are as follows:

[0032] 1. Using a clean blade, remove two 5×5mm, 0.8cm thick sample sheets (polyethylene foam, e.g.) of similar size and shape. Figure 1 As shown, the following examples are the same.

[0033] 2. The sample was pressed using the "mirror image contact pressing method" (see...). Figure 2 ): Place one sample (sample A) in the center of the lower cavity of a clean tableting mold, with the test surface facing upwards. Carefully cover sample A with another sample (sample B), ensuring that its test surface is in relative contact with the test surface of sample A, forming a "mirror contact" structure.

[0034] 3. Compression: Apply pressure by gently placing the upper die head of the mold into the center of the tablet press and applying pressure steadily and slowly at 20 MPa. The compression process should be uniform to avoid impact.

[0035] 4. Hold pressure: Maintain the target pressure for 1 minute.

[0036] 5. Depressurize and remove: Depressurize slowly and carefully open the mold. At this time, the two samples will be tightly pressed together (thickness 0.5 mm).

[0037] 6. Sample Separation: Carefully remove the pressed "mirror-contact" structure from the mold using tweezers. The two samples are usually easy to separate. Select one of them (sample A) as the test sample (the pressed sample has a higher surface density and becomes more compact, as shown in the diagram). Figure 3 ).

[0038] 7. Secure the sample to the SIMS sample stage using the back-side fixing method: Place the test surface of the sample facing the cutout on the sample stage, and press the back of the sample flat with an aluminum block to ensure the sample surface is flat and has good contact with the sample stage. Ensure the sample is firmly fixed and does not wobble.

[0039] 8. Once the sample is prepared, it can be sent into the SIMS chamber for vacuuming and testing.

[0040] The results of testing at different locations on the sample are as follows: Figure 4 As shown, the images at different locations of the same porous material sample are highly consistent, indicating that the method of the present invention has high repeatability.

[0041] Example 2

[0042] This embodiment provides a sample preparation method for secondary ion mass spectrometry analysis of porous materials, the specific steps of which are as follows:

[0043] 1. Using a clean blade, remove two sample slices (1×1cm, 1cm thick) that are similar in size and shape (e.g., ...). Figure 1 (As shown).

[0044] 2. The sample was pressed using the "mirror image contact pressing method" (see...). Figure 2 ): Place one sample (sample A) in the center of the lower cavity of a clean tableting mold, with the test surface facing upwards. Carefully cover sample A with another sample (sample B), ensuring that its test surface is in relative contact with the test surface of sample A, forming a "mirror contact" structure.

[0045] 3. Compression: Apply pressure by gently placing the upper die head of the mold into the center of the tablet press and applying pressure steadily and slowly at 30 MPa. The compression process should be uniform to avoid impact.

[0046] 4. Hold pressure: Maintain the target pressure for 0.5 minutes.

[0047] 5. Depressurize and remove: Depressurize slowly and carefully open the mold. At this time, the two samples will be tightly pressed together (thickness 0.8 mm).

[0048] 6. Sample Separation: Carefully remove the pressed "mirror-contact" structure from the mold using tweezers. The two samples are usually easy to separate. Select one of them (sample A) as the test sample (the pressed sample has a higher surface density and becomes more compact, as shown in the diagram). Figure 3 ).

[0049] 7. Secure the sample to the SIMS sample stage using the back-side fixing method: Place the test surface of the sample facing the cutout on the sample stage, and press the back of the sample flat with an aluminum block to ensure the sample surface is flat and has good contact with the sample stage. Ensure the sample is firmly fixed and does not wobble.

[0050] 8. Once the sample is prepared, it can be sent into the SIMS chamber for vacuuming and testing.

[0051] Example 3

[0052] This embodiment provides a sample preparation method for secondary ion mass spectrometry analysis of porous materials, the specific steps of which are as follows:

[0053] 1. Using a clean blade, remove two sample slices (5×5mm, 0.5cm thick) that are similar in size and shape (e.g., Figure 1 (As shown).

[0054] 2. The sample was pressed using the "mirror image contact pressing method" (see...). Figure 2 ): Place one sample (sample A) in the center of the lower cavity of a clean tableting mold, with the test surface facing upwards. Carefully cover sample A with another sample (sample B), ensuring that its test surface is in relative contact with the test surface of sample A, forming a "mirror contact" structure.

[0055] 3. Compression: Apply pressure by gently placing the upper die head of the mold into the center of the tablet press and applying pressure steadily and slowly at 10 MPa. The compression process should be uniform to avoid impact.

[0056] 4. Hold pressure: Maintain the target pressure for 2 minutes.

[0057] 5. Depressurize and remove: Depressurize slowly and carefully open the mold. At this time, the two samples will be tightly pressed together (thickness 0.2 mm).

[0058] 6. Sample Separation: Carefully remove the pressed "mirror-contact" structure from the mold using tweezers. The two samples are usually easy to separate. Select one of them (sample A) as the test sample (the pressed sample has a higher surface density and becomes more compact, as shown in the diagram). Figure 3 ).

[0059] 7. Secure the sample to the SIMS sample stage using the back-side fixing method: Place the test surface of the sample facing the cutout on the sample stage, and press the back of the sample flat with an aluminum block to ensure the sample surface is flat and has good contact with the sample stage. Ensure the sample is firmly fixed and does not wobble.

[0060] 8. Once the sample is prepared, it can be sent into the SIMS chamber for vacuuming and testing.

[0061] Example 4

[0062] This embodiment provides a sample preparation method for secondary ion mass spectrometry analysis of porous materials, the specific steps of which are as follows:

[0063] 1. Using a clean blade, remove two sample slices (5×5mm, 0.8cm thick) that are similar in size and shape (e.g., Figure 1 (As shown).

[0064] 2. The sample was pressed using the "mirror image contact pressing method" (see...). Figure 2 ): Place one sample (sample A) in the center of the lower cavity of a clean tableting mold, with the test surface facing upwards. Carefully cover sample A with another sample (sample B), ensuring that its test surface is in relative contact with the test surface of sample A, forming a "mirror contact" structure.

[0065] 3. Compression: Apply pressure by gently placing the upper die head of the mold into the center of the tablet press and applying pressure steadily and slowly at 40 MPa. The compression process should be uniform to avoid impact.

[0066] 4. Pressure holding: Maintain the target pressure for 25 seconds.

[0067] 5. Depressurize and remove: Depressurize slowly and carefully open the mold. At this time, the two samples will be tightly pressed together (thickness 0.5 mm).

[0068] 6. Sample Separation: Carefully remove the pressed "mirror-contact" structure from the mold using tweezers. The two samples are usually easy to separate. Select one of them (sample A) as the test sample (the pressed sample has a higher surface density and becomes more compact, as shown in the diagram). Figure 3 ).

[0069] 7. Secure the sample to the SIMS sample stage using the back-side fixing method: Place the test surface of the sample facing the cutout on the sample stage, and press the back of the sample flat with an aluminum block to ensure the sample surface is flat and has good contact with the sample stage. Ensure the sample is firmly fixed and does not wobble.

[0070] 8. Once the sample is prepared, it can be sent into the SIMS chamber for vacuuming and testing.

[0071] Detection was performed at different locations on the sample, but due to poor suppression, no effective mass spectrometry signal could be detected.

[0072] Example 5

[0073] This embodiment provides a sample preparation method for secondary ion mass spectrometry analysis of porous materials, the specific steps of which are as follows:

[0074] 1. Using a clean blade, remove two sample slices (5×5mm, 0.8cm thick) that are similar in size and shape (e.g., Figure 1 (As shown).

[0075] 2. The sample was pressed using the "mirror image contact pressing method" (see...). Figure 2 ): Place one sample (sample A) in the center of the lower cavity of a clean tableting mold, with the test surface facing upwards. Carefully cover sample A with another sample (sample B), ensuring that its test surface is in relative contact with the test surface of sample A, forming a "mirror contact" structure.

[0076] 3. Compression: Apply pressure by gently placing the upper die head of the mold into the center of the tablet press and applying pressure steadily and slowly at 7 MPa. The compression process should be uniform to avoid impact.

[0077] 4. Hold pressure: Maintain the target pressure for 2.5 minutes.

[0078] 5. Depressurize and remove: Depressurize slowly and carefully open the mold. At this time, the two samples will be tightly pressed together (thickness 0.5 mm).

[0079] 6. Sample Separation: Carefully remove the pressed "mirror-contact" structure from the mold using tweezers. The two samples are usually easy to separate. Select one of them (sample A) as the test sample (the pressed sample has a higher surface density and becomes more compact, as shown in the diagram). Figure 3 ).

[0080] 7. Secure the sample to the SIMS sample stage using the back-side fixing method: Place the test surface of the sample facing the cutout on the sample stage, and press the back of the sample flat with an aluminum block to ensure the sample surface is flat and has good contact with the sample stage. Ensure the sample is firmly fixed and does not wobble.

[0081] 8. Once the sample is prepared, it can be sent into the SIMS chamber for vacuuming and testing.

[0082] Detection was performed at different locations on the sample, but due to poor suppression, no effective mass spectrometry signal could be detected.

[0083] Comparative Example 1

[0084] This comparative example provides a sample preparation method (thin-slice preparation method) for secondary ion mass spectrometry analysis of porous materials. The specific steps are as follows:

[0085] Use a blade to slowly remove a thin sheet less than 1 mm thick and fix it onto conductive tape. Then, fix the sample on the secondary ion mass spectrometry sample stage and perform secondary ion mass spectrometry analysis directly.

[0086] Its test results are compared with those of Example 1, for example Figure 5 As shown, it can be observed that although the comparative method can detect mass spectrometry signals, it still exhibits double peaks / abnormal peaks (such as...). Figure 5 (As shown in the box in the middle), and the repeatability is poor, that is, the mass spectrometry signal is not repeated after multiple tests, and the secondary ion mass spectrometry signal of the porous material itself cannot be obtained; while the method of the present invention does not have the above problems and has good repeatability.

[0087] The applicant declares that this invention illustrates the sample preparation method and its application for secondary ion mass spectrometry analysis of porous materials through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

[0088] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0089] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A sample preparation method for secondary ion mass spectrometry analysis of porous materials, characterized in that, The sample preparation method includes the following steps: The sample to be tested is prepared into a sheet sample. Then, two sheet samples are taken, their test surfaces are brought into contact and pressure is applied and maintained. After the pressure is released, one of the sheets is randomly selected as the test sample. Place the test surface of the sample onto the cutout area of ​​the secondary ion mass spectrometry sample stage and flatten it to complete the sample preparation.

2. The sample preparation method for secondary ion mass spectrometry analysis of porous materials according to claim 1, characterized in that, The thickness of the sheet-like sample is 0.5-1 cm.

3. The sample preparation method for secondary ion mass spectrometry analysis of porous materials according to claim 1, characterized in that, The size of the sheet-like sample does not exceed 1cm × 1cm.

4. The sample preparation method for secondary ion mass spectrometry analysis of porous materials according to claim 1, characterized in that, The applied pressure is 10-30 MPa.

5. The sample preparation method for secondary ion mass spectrometry analysis of porous materials according to claim 1, characterized in that, The pressurization process is a uniform pressurization.

6. The sample preparation method for secondary ion mass spectrometry analysis of porous materials according to claim 1, characterized in that, The pressure holding time is 0.5-2 minutes.

7. The sample preparation method for secondary ion mass spectrometry analysis of porous materials according to claim 1, characterized in that, The thickness of the test sample is no more than 1 mm.

8. The sample preparation method for secondary ion mass spectrometry analysis of porous materials according to claim 7, characterized in that, The thickness of the test sample is 0.2-0.8 mm.

9. The sample preparation method for secondary ion mass spectrometry analysis of porous materials according to claim 1, characterized in that, All instruments and tools used in the sample preparation method have been cleaned.

10. The application of a sample preparation method according to any one of claims 1-9 in secondary ion mass spectrometry analysis of porous materials.

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