An element concentration detection method based on laser-induced breakdown spectroscopy

Abstract

The application discloses an element concentration detection method based on laser-induced breakdown spectroscopy, and belongs to the technical field of laser spectrum analysis. The method comprises the following steps: acquiring plasma electron temperature, electron number density and element interference in LIBS of an unknown sample, and then acquiring energy and area of a plasma acoustic spectrum image corresponding to the unknown sample; inputting five features corresponding to the unknown sample into a mapping relationship to obtain a standard spectrum deviation, so as to correct an actual spectrum of a spectrum line to be corrected and obtain a corrected spectrum after elimination of a matrix effect; and finally, substituting the corrected spectrum into a calibration curve to obtain an element concentration after elimination of the influence of the matrix effect. The application summarizes main factors influencing spectral intensity due to the matrix effect, extracts features from LIBS and a plasma acoustic spectrum image, performs fitting and correction on the deviation of each spectrum, and has the advantages of clear physical meaning, no need for pretreatment, no need for complicated parameter adjustment, low cost and small amount of calculation compared with existing methods.

Description

Technical Field

[0001] This invention belongs to the field of laser spectral analysis technology, and more specifically, relates to a method for detecting elemental concentration based on laser-induced breakdown spectroscopy. Background Technology

[0002] Laser-induced breakdown spectroscopy (LIBS) is a technique for analyzing the elemental composition of materials based on atomic and ion emission spectra. It utilizes a high-energy laser to vaporize the surface of a material, generating plasma, and then analyzes the emitted spectrum. The elemental composition of the sample is determined based on the acquired spectral wavelengths, and the elemental content is determined based on the acquired spectral intensities. LIBS has been widely applied in industries such as industrial processing, food analysis, tumor detection, and geology due to its advantages of real-time, rapid, in-situ, and non-destructive analysis.

[0003] However, different types of samples contain different major elements, resulting in significant differences in the spectral intensities of the analyte even under identical experimental conditions and with the same analyte content. This highlights the challenge of matrix effects in LIBS quantification. Researchers have conducted extensive studies and proposed a series of methods to mitigate matrix effect interference, which can be broadly categorized into experimental improvement methods, single-standard calibration methods, algorithm correction methods, and external normalization methods. Experimental improvement methods mainly include laser wavelength optimization and sample pretreatment optimization. While these techniques have some effectiveness, their calibration models are simple and their application is limited. Single-standard calibration methods are suitable for real-time detection applications, but they only utilize the spectral data itself, resulting in limited correction effects. Algorithm correction also has some effect, but it lacks physical meaning and requires substantial data support. Plasma image correction has significant physical meaning and some effectiveness, but the high cost and complex operation of enhanced charge-coupled devices (ICCDs) for capturing plasma images hinder large-scale industrial application.

[0004] In summary, current methods for elemental concentration detection have not yet yielded a solution for the LIBS matrix effect that is effective, cost-effective, and has clear physical meaning. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides an element concentration detection method based on laser-induced breakdown spectroscopy, which aims to solve the technical problems of poor performance and high cost of the LIBS matrix effect solution in the existing element concentration detection methods.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for detecting elemental concentration based on laser-induced breakdown spectroscopy is provided, comprising:

[0007] S1: Acquire the first laser-induced breakdown spectrum (LIBS) and the first plasma acoustic signal of the unknown sample;

[0008] S2: Extract plasma electron temperature, electron number density, and elemental interference from the first LIBS;

[0009] S3: Extract the energy and area of ​​the plasma acoustic spectrum image corresponding to the first plasma acoustic signal;

[0010] S4: The plasma electron temperature, electron number density, elemental interference, energy and area of ​​the plasma acoustic spectrum image corresponding to the unknown sample are substituted into the mapping relationship of the spectral line to be corrected to obtain the standard spectral deviation of the spectral line to be corrected;

[0011] The mapping relationship of the spectral lines to be corrected is used to characterize the plasma electron temperature T and electron number density n of standard samples of various matrices. e The relationship between elemental interference EI, energy E, area S and the standard spectral deviation e of the standard samples of the various matrices;

[0012] S5: Using the standard spectral deviation of the spectral line to be corrected, the actual spectrum I of the spectral line to be corrected is obtained. real After correction, the corrected spectrum I′ after eliminating the matrix effect is obtained;

[0013] S6: Substitute the corrected spectrum I′ into the preset calibration curve to obtain the elemental content of the unknown sample; the calibration curve is the ideal spectrum I′ of the standard samples of the various matrices. ideal Elemental content C of the standard samples of the various matrices s The mapping relationship between them.

[0014] In one embodiment, the process further includes the following step before step S4:

[0015] A1: Obtain the second LIBS and second plasma acoustic signals of the standard samples of the various matrices;

[0016] A2: Determine the spectral line to be corrected from the elemental spectral line database, and use the second LIBS to calculate the ideal spectrum I of the spectral line to be corrected under ideal plasma conditions. ideal ; Utilizing the ideal spectrum I ideal and the content of each element C in the standard sample s Construct the calibration curve;

[0017] A3: Obtain the actual spectrum I of the spectral line to be corrected in the second LIBS. real The actual spectrum I real and the ideal spectrum Iideal The difference is used as the standard spectral deviation e; the plasma electron temperature T and electron number density n are extracted from the second LIBS. e And elemental interference EI; extract plasma acoustic spectrum image energy E and area S from the second plasma acoustic signal to construct the mapping relationship.

[0018] In one embodiment, A2 includes:

[0019] A21: Determine the spectral line to be corrected from the elemental spectral line database, and use the formula... Calculate the ideal spectrum I of the spectral line to be corrected under ideal plasma conditions. ideal Among them, intermediate variables F0, C0, l0, T0, U(T0) and n e0 These are the instrument and environmental factors, the content of the analyte, the radiation path length, the plasma temperature, the partition function, and the electron number density under ideal plasma conditions, respectively. i A ij and E i These represent degeneracy, transition probability, and upper level energy, respectively, where k is the Boltzmann constant, and m... e where E is the electron mass, h is Planck's constant, and E is the electron mass. ion Let ΔE be the ionization energy of the neutral atom of the element to be analyzed. ion It is the ionization potential reduction factor;

[0020] A22: Utilizing the aforementioned ideal spectrum I ideal and the content of each element C in the standard sample s Construct the calibration curve.

[0021] In one embodiment, A22 includes:

[0022] Using formula C s =kI ideal +b, the ideal spectrum I ideal and the content of each element C in the standard sample s Construct the calibration curve; where k and b are coefficients.

[0023] In one embodiment, A3 includes:

[0024] A31: Obtain the actual spectrum I of the spectral line to be corrected in the second LIBS. real ;

[0025] A32: The actual spectrum I real and the ideal spectrum I ideal The difference is taken as the standard spectral deviation e;

[0026] A33: Extract plasma electron temperature T and electron number density n from the second LIBS. e And elemental interference SI; obtain the plasma acoustic spectrum image energy E and area S corresponding to the second plasma acoustic signal;

[0027] A34: Using the formula Construct the mapping relationship Where g1(E) represents the plasma acoustic spectrum image E corresponding to the second plasma acoustic signal and the total particle number density N. s The mapping relationship is as follows: g2(S) represents the mapping relationship between the plasma acoustic spectrum image corresponding to the second plasma acoustic signal and the plasma radiation path length l; g3(Saha) represents the plasma electron temperature T calculated by the second LIBS; g4(FWHM) represents the full width at half maximum (FWHM) and electron number density n of a certain spectral line of the second LIBS that is not affected by the self-absorption effect. e The mapping relationship is as follows: g5(SI) represents the mapping relationship between the spectral intensity SI of the second LIBS interfering element and the elemental interference EI.

[0028] In one embodiment, A32 includes:

[0029] Using the formula e = I real (C,n e ,T,l,EI)-I ideal (C0,n e0 Calculate the standard spectral deviation e using C0, l0, T0, and n. e0 These represent the content of the element to be analyzed, radiation path length, plasma temperature, and electron number density under ideal plasma conditions.

[0030] In one embodiment, S3 includes:

[0031] Wavelet transform is performed on the first plasma acoustic signal to obtain an initial plasma acoustic spectrum image representing the time-domain and frequency-domain information;

[0032] The target plasma acoustic spectrum image is obtained by selecting the audible frequency bands, and the energy and area of ​​the target plasma acoustic spectrum image are extracted.

[0033] According to another aspect of the present invention, an element concentration detection device based on laser-induced breakdown spectroscopy is provided, comprising:

[0034] The acquisition module is used to acquire the first laser-induced breakdown spectrum (LIBS) and the first plasma acoustic signal of the unknown sample;

[0035] The first extraction module is used to extract plasma electron temperature, electron number density and elemental interference from the first LIBS;

[0036] The second extraction module is used to extract the energy and area of ​​the plasma acoustic spectrum image corresponding to the first plasma acoustic signal;

[0037] The first input module is used to input the plasma electron temperature, electron number density, elemental interference, energy and area of ​​the plasma acoustic spectrum image corresponding to the unknown sample into the mapping relationship of the spectral line to be corrected, so as to obtain the standard spectral deviation of the spectral line to be corrected.

[0038] The mapping relationship of the spectral lines to be corrected is used to characterize the plasma electron temperature T and electron number density n of standard samples of various matrices. e The relationship between elemental interference EI, energy E, area S and the standard spectral deviation e of the standard samples of the various matrices;

[0039] The calibration module is used to adjust the actual spectrum I of the spectral line to be calibrated using the standard spectral deviation of the spectral line to be calibrated. real After correction, the corrected spectrum I′ after eliminating the matrix effect is obtained;

[0040] The second input module is used to input the corrected spectrum I′ into a preset calibration curve to obtain the elemental content of the unknown sample; the calibration curve is the ideal spectrum I′ of the standard sample of the various matrices. ideal Elemental content C of the standard samples of the various matrices s The mapping relationship between them.

[0041] According to another aspect of the present invention, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described above.

[0042] According to another aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0043] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0044] (1) This invention provides a method for element concentration detection based on laser-induced breakdown spectroscopy (LIBS). The method acquires the first LIBS spectrum and the first plasma acoustic signal of an unknown sample; extracts the plasma electron temperature, electron number density, and elemental interference from the first LIBS; extracts the energy and area of ​​the plasma acoustic spectrum image corresponding to the first plasma acoustic signal; inputs these five features from the full-band LIBS spectrum and the plasma acoustic spectrum image of the unknown sample into a mapping relationship to obtain a standard spectral deviation; uses the standard spectral deviation to correct the actual spectrum of the spectral line to be corrected to obtain a corrected spectrum after eliminating the matrix effect; finally, substitutes the corrected spectrum into the calibration curve to obtain the element concentration after eliminating the matrix effect. This invention summarizes five main factors affecting spectral intensity due to the matrix effect, extracts features from the full-band LIBS spectrum and the plasma acoustic spectrum image to fit and correct the deviation of each spectrum. Compared with existing methods, this method simultaneously has the advantages of clear physical meaning, no preprocessing required, no cumbersome parameter adjustment required, low cost, and low computational load.

[0045] (2) This scheme acquires full-band spectra and plasma acoustic spectra of multiple standard samples from at least two matrices; calculates the standard spectral intensities of the spectral lines to be calibrated for all standard samples under ideal plasma conditions, and establishes calibration curves between standard spectral intensities and elemental concentrations; and integrates the plasma electron temperature T and electron number density n calculated from LIBS full-band spectra. e The system identifies five features, including elemental interference (SI) and plasma acoustic spectrum image energy (E) and area (S), and establishes a mapping relationship between these features and the standard spectral deviation (e). The operation is simple, and the obtained calibration curves and mapping relationships can accurately characterize the relationship between LIBS full-band spectrum and plasma acoustic spectrum image and elemental concentration.

[0046] (3) This scheme utilizes the formula Calculate the ideal spectrum I of the spectral line to be corrected under ideal plasma conditions. ideal This method takes into account ideal plasma conditions of optical thinness, stoichiometric ablation, and no elemental interference, and realizes the calculation of ideal plasma spectral intensity that eliminates matrix effects.

[0047] (4) This scheme utilizes formula C s =kI ideal +b, the ideal spectrum I ideal and the content of each element C in the standard sample s The calibration curve is constructed; this method takes into account the spectral intensity under ideal plasma conditions that are not affected by matrix effects, and realizes the mapping relationship between spectral intensity and elemental concentration under ideal plasma conditions.

[0048] (5) This scheme utilizes the formula e = I real (C,ne ,T,l,EI)-I ideal (C0,n e0 The standard spectral deviation e is calculated by (T0, l0). This method takes into account the deviation between the actual spectral intensity under the non-ideal plasma state and the spectral intensity under the ideal plasma state, and realizes the quantification of the standard spectral deviation e.

[0049] (6) This plan utilizes Construct the mapping relationship This method considers the mapping relationship between the characteristics of LIBS spectra and plasma acoustic images and five influencing factors of matrix effects, and realizes the indirect characterization of the standard spectral deviation e under unknown element concentration and non-ideal plasma conditions.

[0050] (7) This scheme performs wavelet transform on the first plasma acoustic signal to obtain the initial plasma acoustic spectrum image corresponding to the time domain information and frequency domain information; selects the audible part frequency band to obtain the target plasma acoustic spectrum image. This method takes into account the problem that the transient characteristics of the plasma acoustic signal make it difficult to obtain the mapping relationship between the time domain signal and the plasma evolution. Wavelet transform is performed to realize the mapping of the time and frequency domain evolution of the plasma acoustic spectrum image to the plasma evolution process. Attached Figure Description

[0051] Figure 1 The flowchart shows a method for detecting elemental concentration based on laser-induced breakdown spectroscopy provided in Embodiment 1 of the present invention.

[0052] Figure 2 for Figure 1 A schematic diagram of the corresponding element concentration detection device based on laser-induced breakdown spectroscopy;

[0053] Figure 3 for Figure 2 A schematic diagram of the acquisition of plasma acoustic signals and the transformed plasma acoustic spectrum image;

[0054] Figure 4 for Figure 2 A schematic diagram of the three-dimensional morphology of ablation pits after different energy treatments, the acquired LIBS full-band spectrum, and the plasma acoustic spectrum image;

[0055] Figure 5 for Figure 2 A graph showing the functional relationship between energy E and ablation amount M in the plasma acoustic spectrum image of microalloyed steel sample No. 1.

[0056] Figure 6 for Figure 2 A schematic diagram showing the area of ​​the acquired plasma acoustic spectrum image and the fluctuations on different substrates;

[0057] Figure 7 The calibration curves of the two spectral lines MnⅡ 344.20nm and FeⅡ 239.56nm in the metal sample provided in Example 1 of the present invention before and after plasma acoustic spectrum image-spectral fusion calibration.

[0058] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0059] 1-Computer, 2-Acquisition card, 3-Acoustic pressure constant current source, 4-Microphone, 5-Plasma acoustic signal, 6-3D displacement platform, 7-Timing controller, 8-Six-channel fiber optic spectrometer, 9-Reflector, 10-Nd:YAG nanosecond pulsed laser, 11-Laser beam, 12-Spectral acquisition head, 13-Focusing lens, 14-Spectral coupling lens, 15-Laser-induced breakdown spectrum, 16-Sample, 17-Plasma. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0061] Example 1

[0062] like Figure 1 As shown, this embodiment of the invention provides a method for elemental concentration detection based on laser-induced breakdown spectroscopy, including: S1-S6. Specifically, S1: acquiring the first laser-induced breakdown spectrum (LIBS) and the first plasma acoustic signal of an unknown sample. S2: extracting the plasma electron temperature, electron number density, and elemental interference from the first LIBS. S3: extracting the energy and area of ​​the plasma acoustic spectrum image corresponding to the first plasma acoustic signal. S4: substituting the plasma electron temperature, electron number density, elemental interference, energy, and area of ​​the plasma acoustic spectrum image corresponding to the unknown sample into the mapping relationship of the spectral line to be corrected, obtaining the standard spectral deviation of the spectral line to be corrected. The mapping relationship of the spectral line to be corrected is used to characterize the plasma electron temperature T and electron number density n of standard samples corresponding to various matrices. e The relationship between elemental interference EI, energy E, area S, and the standard spectral deviation e of standard samples from various matrices. S5: Using the standard spectral deviation of the spectral line to be corrected, the actual spectrum I of the spectral line to be corrected. realCorrection is performed to obtain the corrected spectrum I′ after eliminating matrix effects. S6: Substitute the corrected spectrum I′ into the preset calibration curve to obtain the elemental content of the unknown sample. The calibration curve is the ideal spectrum I′ of standard samples with various matrices. ideal Elemental content C of standard samples with various matrices s The mapping relationship between them.

[0063] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but may be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but may be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0064] As a preferred embodiment, before S4, the method further includes: A1: acquiring the second LIBS and second plasma acoustic signals of standard samples from various matrices. A2: determining the spectral line to be corrected from an elemental spectral line database, and calculating the ideal spectrum I of the spectral line to be corrected under ideal plasma conditions using the second LIBS. ideal Using ideal spectrum I ideal The content of each element C in the standard sample s Construct the calibration curve. A3: Obtain the actual spectrum I of the spectral line to be calibrated in the second LIBS. real , to the actual spectrum I real and ideal spectrum I ideal The difference is used as the standard spectral deviation e. Plasma electron temperature T and electron number density n are extracted from the second LIBS. e And elemental interference EI. The plasma acoustic spectrum image energy E and area S are extracted from the second plasma acoustic signal to construct a mapping relationship.

[0065] Step A1: Obtain the second LIBS full-band spectrum and the second plasma acoustic signal for at least two matrices (at least 3 standard samples for each matrix).

[0066] Specifically, such as Figure 2As shown, in this embodiment, five standard samples of known element types and concentrations from each of the three matrices—aluminium alloy, iron (microalloy steel), and titanium (TC4)—were placed on a 3D displacement platform 6. With a defocusing depth of -3 mm, an Nd:YAG nanosecond pulsed laser 10 with a wavelength of 532 nm was used. A six-channel fiber optic spectrometer 8 was used with a gate width of 9 μs and a delay of 2 μs. The sampling rate of the acquisition card 2 was 400 kHz. Each sample was excited 400 times with an energy of 80 mJ, and 400 pairs of second LIBS full-band spectra 15 and second laser-induced plasma acoustic signals 5 were acquired.

[0067] Step A2: Determine the spectral lines of the element to be corrected based on the elemental spectral line database, and calculate the ideal plasma state spectrum I of the standard samples of all matrices under the second LIBS full-band spectroscopy. ideal To demonstrate that a calibration model can be established using any two matrices, two sets of calibration matrices were selected, and calibration models were established for each to prove the broad applicability of this method. Specifically, Mn was selected between aluminum-based and iron-based matrices, and Fe was selected between aluminum-based and titanium-based matrices for calibration demonstration. The contents of Mn and Fe in the selected aluminum-based, iron-based, and titanium-based samples are shown in Table 1, where the serial number represents the standard sample number in each matrix.

[0068] Table 1. Mn and Fe elemental contents (wt.%) in aluminum-based, iron-based, and titanium-based alloys.

[0069]

[0070] In this embodiment, the Mn II 344.20 nm spectral line corresponding to Mn and the Fe II 239.56 nm spectral line corresponding to Fe are selected for demonstration of calibration model establishment. When establishing calibration models using both aluminum-based and iron-based matrices, samples 1 from the aluminum-based matrix and samples 2 and 5 from the iron-based matrix are selected as test samples to evaluate the calibration effect of the calibration model on unknown samples, with the remaining 7 serving as training samples. When establishing calibration models using both aluminum-based and titanium-based matrices, samples 1 from the aluminum-based matrix and samples 2 and 5 from the iron-based matrix are selected as test samples to evaluate the calibration effect of the calibration model on unknown samples, with the remaining 7 serving as training samples. Based on the second LIBS full-band spectrum, according to the LIBS spectral line integral intensity expression formula, the standard spectral intensity I of the Mn II 344.20 nm spectral line of the aluminum-based and iron-based matrix training samples and the Fe II 239.56 nm spectral line of the aluminum-based and titanium-based matrix training samples under ideal plasma conditions are calculated respectively. ideal Its formula is as follows:

[0071]

[0072] F0, C0, l0, T0, U(T0) and n e0 These are the instrument and environmental factors, the content of the analyte, the radiation path length, the plasma temperature, the partition function, and the electron number density under ideal plasma conditions, respectively. i A ij and E i These represent degeneracy, transition probability, and upper level energy, respectively, where k is the Boltzmann constant, and m... e where E is the electron mass, h is Planck's constant, and E is the electron mass. ion Let ΔE be the ionization energy of the neutral atom of the element to be analyzed. ion It is the ionization potential reduction factor.

[0073] Next, we establish the spectrum I under ideal plasma conditions. ideal With element content C s The calibration curves between them; specifically, based on the calculated Mn II 344.20 nm spectral line of the aluminum-based and iron-based training samples under ideal plasma conditions and the standard spectral intensity I of the aluminum-based and titanium-based training samples at 239.56 nm. ideal Then, the corresponding element concentrations C in Table 1 are... s Substitute into the calibration curve equation: C s =kI ideal +b. The obtained calibration curve is as follows: Figure 7 (a) and Figure 7 The black solid line in (c) shows the calibration curve obtained using actual spectral intensities and the curve obtained by calculating the standard spectral intensities I. ideal The significant deviation stems from matrix effects. However, the standard spectral intensity I... ideal The calculation requires prior knowledge of the content C0 of the element to be analyzed. When the calibration line is used for an unknown sample, the element content is unknown, so the standard spectral intensity I cannot be calculated. ideal Other parameters are needed to indirectly characterize the standard spectral intensity I. ideal The calculation factor is used to achieve spectral correction for unknown samples, and the corrected calibration curve is shown below. Figure 7 (b) and Figure 7 The black solid line in (d) is shown.

[0074] Step A3: Obtain the actual spectral intensity I of the spectral line to be corrected in the second LIBS full-band spectrum. real And calculate the standard spectral deviation e = I real -I ideal .

[0075] Specifically, the actual intensity I of the spectral line Mn II at 344.20 nm for aluminum-based and iron-based training samples, and the spectral line Fe II at 239.56 nm for aluminum-based and titanium-based training samples were extracted from the second LIBS full-band spectrum collected in the experiment. real (C,n e ,T,l), and based on the standard spectral intensity I under the ideal plasma state. ideal (C0,n e0 Calculate the deviation e of the spectral lines at 344.20 nm for MnII and 239.56 nm for FeII, and the actual spectral intensity I. real Compared with standard spectral intensity I ideal The deviation e between them is:

[0076] e = I real (C,n e ,T,l)-I ideal (C0,n e0 ,T0,l0).

[0077] Next, the plasma electron temperature T and electron number density n were extracted from the second LIBS full-band spectrum. e Interference with elements SI; extract the plasma acoustic spectrum image energy E and area S corresponding to the second plasma acoustic signal; specifically, the collected... Figure 3 The plasma acoustic signal shown in (a) is transformed by wavelet time-frequency transformation to obtain a plasma acoustic spectrum image, from which the audible frequency bands are extracted as follows: Figure 3 As shown in (b), the second relationship between the plasma acoustic spectrum image area S and the matrix is ​​extracted through image features, as follows: Figure 6 As shown, the area S of the plasma acoustic spectrum image exhibits a significant matrix effect.

[0078] Figure 4 Image (a) in the image is a photograph taken by laser confocal microscopy of Micro Alloysteel Sample 1 under different laser energies. Figure 4 (b) in the figure represents the LIBS spectra acquired under different laser energies. Figure 4 (c) in the image shows plasma acoustic spectrum images acquired under different laser energies. Figure 4 As shown in (a), based on the ablation mass M of the sample at different energies obtained from laser confocal microscopy, the energy feature E in the plasma acoustic spectrum image is extracted, and the first relationship between the plasma acoustic spectrum image energy E and the sample ablation mass M is established as follows: Figure 5 As shown, the plasma acoustic spectrum image energy E and the sample ablation mass M are linearly related.

[0079] Based on the above relationship, the features corresponding to the influencing factors of spectral deviation extracted from the plasma acoustic spectrum image of the sample include: plasma acoustic spectrum image energy E and plasma acoustic spectrum image area S; the features corresponding to the influencing factors of spectral deviation extracted from the full-band LIBS spectrum of the sample include: full width at half maximum (FWHM) of the HI 656.28nm elemental spectral line, plasma electron temperature T, and spectral intensity SI of interfering elements.

[0080] Among them, the plasma acoustic spectrum image energy E represents the total particle number density N. s The area S of the plasma acoustic spectrum image represents the plasma radiation path length l. The plasma electron temperature T of the LIBS full-band spectrum is calculated using the Saha Boltzmann oblique line method. The full width at half maximum (FWHM) of the 656.28 nm elemental spectral line represents the electron number density n. e The spectral intensity (SI) of interfering elements characterizes the elemental interference (EI).

[0081] N s =g1(E);

[0082] l = g2(S);

[0083] T = g3(Saha);

[0084] n e =g4(FWHM);

[0085] EI = g5(SI).

[0086] Finally, the plasma electron temperature T and electron number density n were established. e The mapping relationship between five features, including elemental interference (SI), image energy (E), and area (S), and the standard spectral deviation (e), was established. Specifically, based on five spectral deviation-related features extracted from LIBS full-band spectra and plasma acoustic spectra, the mapping relationships for the estimated standard spectral deviation (e) of the spectral line MnII (344.20 nm) for aluminum-based and iron-based materials, and the spectral line FeII (239.56 nm) for aluminum-based and titanium-based materials were obtained.

[0087] e=f(g1(E),g2(S),g3(Saha),g4(FWHM),g5(SI));

[0088] After obtaining this model, for the test set samples that were not involved in the modeling, the plasma electron temperature T and electron number density n were extracted from the LIBS full-band spectrum. e By removing the elemental interference SI, the plasma acoustic signal energy E and area S corresponding to the plasma acoustic spectrum image are extracted; by substituting them into the above mapping relationship, the standard spectral deviation e can be obtained.

[0089] S1-S3: Acquire the first LIBS full-band spectrum and the first plasma acoustic signal of the unknown sample; extract the plasma electron temperature T and electron number density n from the first LIBS full-band spectrum. e Interference with elements SI; extract the plasma acoustic spectrum image energy E and area S corresponding to the first plasma acoustic signal.

[0090] Specifically, unknown samples are test samples that did not participate in the establishment of the mapping relationship. The second LIBS full-band spectrum and the second plasma acoustic signal of the test sample selected in step A1 are combined to form the first LIBS full-band spectrum and the first plasma acoustic signal; the plasma electron temperature T and electron number density n of the first LIBS full-band spectrum are extracted. e Interference with elements SI; extract the plasma acoustic spectrum image energy E and area S corresponding to the first plasma acoustic signal.

[0091] S4: Substitute the five features into the mapping relationship of the spectral line to be corrected to obtain the standard spectral deviation of the spectral line to be corrected.

[0092]

[0093] S5: Using the standard spectral deviation e, the actual spectrum I of the spectral line to be corrected in the first LIBS full-band spectrum. real Correction was performed to obtain the corrected spectrum I′ after eliminating the matrix effect; specifically, based on the deviation calculated by S4, the spectral line Mn II 344.20 nm for aluminum-based and iron-based materials, and the spectral line Fe II 239.56 nm for aluminum-based and titanium-based materials were corrected.

[0094] I′=I real (N s ,l,T,n e )-f(g1(E),g2(S),g3(Saha),g4(FWHM),g5(SI)).

[0095] S6: Substituting the corrected spectrum I′ into the pre-established calibration curve yields the elemental content; substituting the spectral intensity I′ of the aluminum-based and iron-based Mn II 344.20nm and the spectral intensity I′ of the aluminum-based and titanium-based Fe II 239.56nm into the pre-established calibration curve yields the elemental concentration C. s Prediction: C s =kI′+b. Based on the above steps, the Mn element in aluminum-based and iron-based materials, and the Fe element in aluminum-based and titanium-based materials, are corrected. The correction results are as follows: Figure 7 (b) and Figure 7 As shown in (d); R of the Mn element calibration lines for aluminum-based and iron-based materials. 2MAPE and RMSE improved from 0.7174, 54.356, and 401.297 before correction to 0.9996, 58.496, and 11.991, respectively; the R value of the Fe element calibration lines for aluminum-based and titanium-based materials was also improved. 2 MAPE and RMSE improved from 0.3614, 65.860, and 161.803 before correction to 0.9832, 2.680, and 12.478, respectively. Matrix effects between aluminum-based and iron-based materials, as well as between aluminum-based and titanium-based materials, were well suppressed.

[0096] Therefore, this embodiment verifies that the elemental concentration detection method based on laser-induced breakdown spectroscopy proposed in this invention provides an effective, simple, low-cost, and easy-to-operate solution for the correction of matrix effects.

[0097] As a preferred embodiment, A2 includes: A21: determining the spectral line to be corrected from an elemental spectral line database, and using the formula Calculate the ideal spectrum I of the spectral line to be corrected under ideal plasma conditions. ideal Among them, intermediate variables F0, C0, l0, T0, U(T0) and n e0 These are the instrument and environmental factors, the content of the analyte, the radiation path length, the plasma temperature, the partition function, and the electron number density under ideal plasma conditions, respectively. i A ij and E i These represent degeneracy, transition probability, and upper level energy, respectively, where k is the Boltzmann constant, and m... e where E is the electron mass, h is Planck's constant, and E is the electron mass. ion Let ΔE be the ionization energy of the neutral atom of the element to be analyzed. ion This is the ionization potential decrease factor. A22: Utilizing ideal spectrum I ideal The content of each element C in the standard sample s Construct calibration curves.

[0098] As a preferred embodiment, A22 includes: utilizing formula C s =kI ideal +b、Ideal Spectrum I ideal The content of each element C in the standard sample s Construct a calibration curve. Here, k and b are coefficients.

[0099] As a preferred embodiment, A3 includes: A31: obtaining the actual spectrum I of the spectral line to be corrected in the second LIBS. real A32: The actual spectrum I real and ideal spectrum I idealThe difference is used as the standard spectral deviation e. A33: Extract plasma electron temperature T and electron number density n from the second LIBS. e Interference with elements SI. Obtain the plasma acoustic spectrum image energy E and area S corresponding to the second plasma acoustic signal. A34: Using the formula Build mapping relationship Where g1(E) represents the plasma acoustic spectrum image E corresponding to the second plasma acoustic signal and the total particle number density N. s The mapping relationship is as follows: g2(S) represents the mapping relationship between the plasma acoustic spectrum image corresponding to the second plasma acoustic signal and the plasma radiation path length l. g3(Saha) represents the plasma electron temperature T calculated from the second LIBS, and g4(FWHM) represents the full width at half maximum (FWHM) and electron number density n of a certain spectral line of the second LIBS that is not affected by the self-absorption effect. e The mapping relationship is shown in g5(SI), which represents the mapping relationship between the spectral intensity SI of the second LIBS interfering element and the elemental interference EI.

[0100] As a preferred embodiment, A32 includes: using the formula e = I real (C,n e ,T,l,EI)-I ideal (C0,n e0 Calculate the standard spectral deviation e using C0, l0, T0, and n. e0 These represent the content of the element to be analyzed, radiation path length, plasma temperature, and electron number density under ideal plasma conditions.

[0101] As a preferred implementation, S3 includes: performing wavelet transform on the first plasma acoustic signal to obtain an initial plasma acoustic spectrum image corresponding to the time domain information and frequency domain information; selecting the audible frequency band from it to obtain a target plasma acoustic spectrum image; and extracting the energy and area of ​​the target plasma acoustic spectrum image.

[0102] Example 2

[0103] This embodiment provides an element concentration detection device based on laser-induced breakdown spectroscopy, including: an acquisition module, a first extraction module, a second extraction module, a first input module, a correction module, and a second input module.

[0104] The acquisition module is used to acquire the first laser-induced breakdown spectrum (LIBS) and the first plasma acoustic signal of the unknown sample.

[0105] The first extraction module is used to extract plasma electron temperature, electron number density and elemental interference from the first LIBS.

[0106] The second extraction module is used to extract the energy and area of ​​the plasma acoustic spectrum image corresponding to the first plasma acoustic signal.

[0107] The first input module is used to input the plasma electron temperature, electron number density, elemental interference, energy and area of ​​the plasma acoustic spectrum image corresponding to the unknown sample into the mapping relationship of the spectral line to be corrected, so as to obtain the standard spectral deviation of the spectral line to be corrected.

[0108] The mapping relationship of the spectral lines to be corrected is used to characterize the plasma electron temperature T and electron number density n of standard samples of various matrices. e The relationship between elemental interference EI, energy E, area S and standard spectral deviation e of standard samples from various matrices.

[0109] The calibration module is used to utilize the standard spectral deviation of the spectral line to be calibrated to the actual spectrum I of the spectral line. real Correction is performed to obtain the corrected spectrum I′ after eliminating matrix effects.

[0110] The second input module is used to input the corrected spectrum I′ into a preset calibration curve to obtain the elemental content of the unknown sample. The calibration curve is the ideal spectrum I′ of standard samples from various matrices. ideal Elemental content C of standard samples with various matrices s The mapping relationship between them.

[0111] Example 3

[0112] This embodiment provides an electronic device, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described method.

[0113] Example 4

[0114] This embodiment provides a computer-readable storage medium on which a computer program is stored, which, when executed by a processor, implements the steps of the above method.

[0115] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0116] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0117] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0118] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0119] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the invention is intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0120] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of protection of this invention, this invention also intends to include these modifications and variations.

[0121] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting elemental concentration based on laser-induced breakdown spectroscopy, characterized in that, include: S1: Acquire the first laser-induced breakdown spectrum (LIBS) and the first plasma acoustic signal of the unknown sample; S2: Extract plasma electron temperature, electron number density, and elemental interference from the first LIBS; S3: Extract the energy and area of ​​the plasma acoustic spectrum image corresponding to the first plasma acoustic signal; S4: The plasma electron temperature, electron number density, elemental interference, energy and area of ​​the plasma acoustic spectrum image corresponding to the unknown sample are substituted into the mapping relationship of the spectral line to be corrected to obtain the standard spectral deviation of the spectral line to be corrected; The mapping relationship of the spectral lines to be corrected is used to characterize the plasma electron temperature T and electron number density n of standard samples of various matrices. e The relationship between elemental interference EI, energy E, area S and the standard spectral deviation e of the standard samples of the various matrices; S5: Using the standard spectral deviation of the spectral line to be corrected, the actual spectrum I of the spectral line to be corrected is obtained. real Correction is performed to obtain the corrected spectrum I′ after eliminating matrix effects; S6: Substitute the corrected spectrum I′ into the preset calibration curve to obtain the elemental content of the unknown sample; the calibration curve is the ideal spectrum I′ of the standard samples of the various matrices. ideal Elemental content C of the standard samples of the various matrices s The mapping relationship between them; The following is included before S4: A1: Obtain the second LIBS and second plasma acoustic signals of the standard samples of the various matrices; A2: Determine the spectral line to be corrected from the elemental spectral line database, and use the second LIBS to calculate the ideal spectrum I of the spectral line to be corrected under ideal plasma conditions. ideal ; Utilizing the ideal spectrum I ideal and the content of each element C in the standard sample s Construct the calibration curve; A3: Obtain the actual spectrum I of the spectral line to be corrected in the second LIBS. real The actual spectrum I real and the ideal spectrum I ideal The difference is used as the standard spectral deviation e; the plasma electron temperature T and electron number density n are extracted from the second LIBS. e And elemental interference EI; extract plasma acoustic spectrum image energy E and area S from the second plasma acoustic signal to construct the mapping relationship; A3 includes: A31: Obtain the actual spectrum I of the spectral line to be corrected in the second LIBS. real ; A32: The actual spectrum I real and the ideal spectrum I ideal The difference is taken as the standard spectral deviation e; A33: Extract plasma electron temperature T and electron number density n from the second LIBS. e And elemental interference SI; obtain the plasma acoustic spectrum image energy E and area S corresponding to the second plasma acoustic signal; A34: Using the formula Construct the mapping relationship Where g1(E) represents the plasma acoustic spectrum image E corresponding to the second plasma acoustic signal and the total particle number density N. s The mapping relationship is as follows: g2(S) represents the mapping relationship between the plasma acoustic spectrum image corresponding to the second plasma acoustic signal and the plasma radiation path length l; g3(Saha) represents the plasma electron temperature T calculated by the second LIBS; g4(FWHM) represents the full width at half maximum (FWHM) and electron number density n of a certain spectral line of the second LIBS that is not affected by the self-absorption effect. e The mapping relationship is as follows: g5(SI) represents the mapping relationship between the spectral intensity SI of the second LIBS interfering element and the elemental interference EI.

2. The element concentration detection method based on laser-induced breakdown spectroscopy as described in claim 1, characterized in that, A2 includes: A21: Determine the spectral line to be corrected from the elemental spectral line database, and use the formula... Calculate the ideal spectrum I of the spectral line to be corrected under ideal plasma conditions. ideal Among them, intermediate variables F0, C0, l0, T0, U(T0) and n e0 These are the instrument and environmental factors, the content of the analyte, the radiation path length, the plasma temperature, the partition function, and the electron number density under ideal plasma conditions, respectively. i A ij and E i These represent degeneracy, transition probability, and upper level energy, respectively, where k is the Boltzmann constant, and m... e where E is the electron mass, h is Planck's constant, and E is the electron mass. ion Let ΔE be the ionization energy of the neutral atom of the element to be analyzed. ion It is the ionization potential decrease factor; A22: Utilizing the aforementioned ideal spectrum I ideal and the content of each element C in the standard sample s Construct the calibration curve.

3. The element concentration detection method based on laser-induced breakdown spectroscopy as described in claim 2, characterized in that, A22 includes: Using formula C s =kI ideal +b, the ideal spectrum I ideal and the content of each element C in the standard sample s Construct the calibration curve; where k and b are coefficients.

4. The element concentration detection method based on laser-induced breakdown spectroscopy as described in claim 1, characterized in that, The A32 includes: Using the formula e = I real (C,n e ,T,l,EI)-I ideal (C0,n e0 Calculate the standard spectral deviation e using C0, l0, T0, and n. e0 These represent the content of the element to be analyzed, radiation path length, plasma temperature, and electron number density under ideal plasma conditions.

5. The element concentration detection method based on laser-induced breakdown spectroscopy as described in any one of claims 1-4, characterized in that, S3 includes: Wavelet transform is performed on the first plasma acoustic signal to obtain an initial plasma acoustic spectrum image representing the time-domain and frequency-domain information; The target plasma acoustic spectrum image is obtained by selecting the audible frequency bands, and the energy and area of ​​the target plasma acoustic spectrum image are extracted.

6. An element concentration detection device based on laser-induced breakdown spectroscopy, characterized in that, include: The acquisition module is used to acquire the first laser-induced breakdown spectrum (LIBS) and the first plasma acoustic signal of the unknown sample; The first extraction module is used to extract plasma electron temperature, electron number density and elemental interference from the first LIBS; The second extraction module is used to extract the energy and area of ​​the plasma acoustic spectrum image corresponding to the first plasma acoustic signal; The first input module is used to input the plasma electron temperature, electron number density, elemental interference, energy and area of ​​the plasma acoustic spectrum image corresponding to the unknown sample into the mapping relationship of the spectral line to be corrected, so as to obtain the standard spectral deviation of the spectral line to be corrected. The mapping relationship of the spectral lines to be corrected is used to characterize the plasma electron temperature T and electron number density n of standard samples of various matrices. e The relationship between elemental interference EI, energy E, area S and the standard spectral deviation e of the standard samples of the various matrices; The calibration module is used to adjust the actual spectrum I of the spectral line to be calibrated using the standard spectral deviation of the spectral line to be calibrated. real After correction, the corrected spectrum I′ after eliminating the matrix effect is obtained; The second input module is used to input the corrected spectrum I′ into a preset calibration curve to obtain the elemental content of the unknown sample; the calibration curve is the ideal spectrum I′ of the standard sample of the various matrices. ideal Elemental content C of the standard samples of the various matrices s The mapping relationship between them.

7. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

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