Surface-enhanced Raman probe as well as preparation and application thereof

Abstract

The invention discloses a surface-enhanced Raman probe as well as preparation and application thereof. The surface-enhanced Raman probe comprises a silver nanorod and a 4-amino thiophenol molecular layer adsorbed on the surface of the silver nanorod, pATP molecules and the surface of the silver nanorod form an Ag-S bond through sulfydryl (-SH) to form AgNRs (at) PATP, the two AgNRs (at) PATP molecules easily form a corresponding azo compound DMAB, and a pi-pi conjugated structure between the DMAB and nitro explosive molecules can effectively promote electron transfer, combine into AgNRs (at) PATP (at) TNT and generate a hot spot signal, so that a Raman signal is enhanced, the detection limit is reduced, the accuracy is high, and the method is suitable for industrial production. The trace detection of the nitro explosives is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of explosive detection, and in particular to a surface enhanced Raman probe and its preparation and application. Background Art

[0002] With the increasing frequency of security incidents, efficient and accurate explosives detection technology is urgently needed to address counterterrorism, environmental monitoring, and public safety needs. Traditional detection methods, such as X-ray / gamma-ray imaging, ion mobility spectrometry, electrochemical methods, and mass spectrometry, suffer from bottlenecks such as expensive equipment, bulky size, reliance on complex preprocessing, and the inability to conduct real-time on-site detection. These limitations make them difficult to meet the requirements for rapid identification of trace explosives and intrinsically safe detection.

[0003] Surface-enhanced Raman scattering (SERS) has shown great potential in explosives detection. By utilizing specific metal nanostructures to significantly amplify Raman signals, SERS enables highly sensitive identification of trace substances. Compared to traditional detection methods, SERS offers several unique advantages: First, it has an extremely high enhancement factor, sufficient to support single-molecule detection; second, the spectral peaks produced by SERS are clear and sharp, with minimal overlap between different chemical species, facilitating precise differentiation of compounds; third, the technique is suitable for simultaneous detection of multiple components and can rapidly acquire sample information within seconds, making it particularly suitable for applications requiring rapid response. Importantly, SERS has low sample requirements, requires no tedious pretreatment, and is less susceptible to interference from fluorescence background, making it more convenient and reliable in practical applications. Despite its numerous advantages, the sensitivity and accuracy of fiber-optic sensing systems for explosives detection still need to be improved.

[0004] Therefore, it is necessary to provide a technical solution to achieve sensitivity and accuracy in explosive detection using surface enhanced Raman spectroscopy (SERS) technology. Summary of the Invention

[0005] In view of this, the present application provides a surface-enhanced Raman probe and its preparation and application, which are used to solve the problem of how to use surface-enhanced Raman spectroscopy (SERS) technology to achieve sensitivity and accuracy in explosive detection.

[0006] In order to achieve the above technical objectives, this application adopts the following technical solutions: In a first aspect, the present application provides a surface-enhanced Raman probe comprising silver nanorods and a 4-aminothiophenol molecular layer adsorbed on the surface of the silver nanorods.

[0007] In a second aspect, the present application provides a method for preparing a surface-enhanced Raman probe, comprising the following steps: S1. dispersing a polymer stabilizer, a halide additive, and a silver source in an ethylene glycol solvent and performing a redox reaction to obtain silver nanorods; S2. Silver nanorods are mixed with 4-aminothiophenol to undergo a self-assembly reaction to obtain a surface-enhanced Raman probe.

[0008] Preferably, the polymer stabilizer comprises polyvinyl pyrrolidone; the halide additive comprises sodium chloride; and the silver source comprises silver nitrate.

[0009] Preferably, the molar ratio of the silver source to 4-aminothiophenol is 1:10.

[0010] Preferably, the temperature of the redox reaction is 150-180°C; the temperature of the self-assembly reaction is 20-40°C.

[0011] In a second aspect, the present application provides an application of a surface-enhanced Raman probe in detecting trace amounts of nitro explosives.

[0012] Preferably, the nitro-based explosive comprises TNT.

[0013] Preferably, the method comprises the following steps: K1. The surface-enhanced Raman probe is mixed with a standard analyte gradient solution and a test explosive solution to obtain a corresponding standard analyte group and the test substance; K2. Immerse the cleaned optical fiber end faces in the standard analyte group and the analyte, respectively, and remove and dry them to obtain the corresponding standard analyte optical fiber end face group and the optical fiber end face to be analyzed; K3. Use a fiber optic sensing system to couple laser light to the standard analyte fiber end face set and the end face of the fiber to be analyzed, and collect SERS signals to obtain the Raman spectral characteristic peak intensities of the standard analyte set and the analyte to be analyzed. K4. Establish a concentration-peak intensity standard curve based on the Raman spectral peak intensities of the standard analyte group. Substitute the characteristic peak intensities of the Raman spectroscopy of the analyte into the standard curve to obtain the concentration of the explosive to be tested.

[0014] Preferably, the laser parameters of the optical fiber sensing system are: wavelength of 785±5 nm, power of 6±0.5 mW, and integration time of 4-5 seconds.

[0015] In a third aspect, the present application provides a fiber optic sensing system, comprising an optical excitation unit, a fiber optic coupling unit, and a signal acquisition unit; the optical excitation unit comprises a laser, a collimator, a first dielectric film reflector, a second dielectric film reflector, and a dichroic mirror arranged in sequence along the optical path; the fiber optic coupling unit comprises an objective lens and a three-dimensional precision translation stage, the three-dimensional precision translation stage is used to fix the optical fiber, and the dichroic mirror reflects the laser to the objective lens and couples it into the optical fiber end face; the signal acquisition unit comprises a first long-pass filter, a second long-pass filter, a lens sleeve, a five-axis coupler, and a spectrometer arranged in sequence along the optical path.

[0016] The beneficial effects of the present application are as follows: The present application utilizes PATP molecules to form Ag-S bonds with the surface of silver nanorods through thiol (-SH) to form AgNRs@PATP, and two AgNRs@PATP molecules easily form the corresponding azo compound DMAB. The π-π conjugated structure between DMAB and the nitro explosive molecule can effectively promote electron transfer, combining to form AgNRs@PATP@TNT, generating a "hotspot" signal, resulting in enhanced Raman signals, lowering the detection limit, and realizing trace detection of nitro explosives. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic structural diagram of the optical fiber sensing system of this application; In the figure, 1. Laser; 2. Collimator; 3. First dielectric film mirror; 4. Second dielectric film mirror; 5. Dichroic mirror; 6. Objective lens; 7. Three-dimensional precision translation stage; 8. Optical fiber; 9. First long-pass filter; 10. Lens sleeve; 11. Second long-pass filter; 12. Five-axis coupler; 13. Spectrometer.

[0018] Figure 2 TME diagram of AgNRs and AgNRs@PATP; Figure 3 Raman spectra of TNT, AgNRs@PATP, and AgNRs@PATP@TNT; Figure 4 The results of the specific test are as follows; Figure 5 is the concentration-peak intensity standard curve; Figure 6 is the characteristic peak intensity of Raman spectra of different analytes. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] The present application provides a surface-enhanced Raman probe, which includes silver nanorods and a 4-aminothiophenol molecular layer adsorbed on the surface of the silver nanorods.

[0021] In this application, PATP molecules form Ag-S bonds with the surface of silver nanorods through thiol (-SH) groups to form AgNRs@PATP, and two AgNRs@PATP molecules easily form the corresponding azo compound, namely DMAB. The π-π conjugated structure between DMAB and nitro explosives (such as TNT) molecules can effectively promote electron transfer, combining to form AgNRs@PATP@TNT, generating "hotspot" signals, resulting in enhanced Raman signals, lowering the detection limit, and realizing trace detection of nitro explosives.

[0022] The present application provides a method for preparing a surface-enhanced Raman probe, comprising the following steps: S1. dispersing a polymer stabilizer, a halide additive, and a silver source in an ethylene glycol solvent and performing a redox reaction to obtain silver nanorods; S2. Silver nanorods are mixed with 4-aminothiophenol to undergo a self-assembly reaction to obtain a surface-enhanced Raman probe.

[0023] In this application, ethylene glycol is used as a reducing agent and solvent to promote the directional reduction of silver nitrate at high temperature to form uniform silver nanorods, while 4-aminothiophenol (PATP) is rapidly adsorbed on the surface of silver nanorods through molecular self-assembly at room temperature to form a single layer of dense modification.

[0024] In some embodiments, the polymer stabilizer comprises polyvinyl pyrrolidone; the halide additive comprises sodium chloride; and the silver source comprises silver nitrate.

[0025] In this embodiment, ethylene glycol is gradually oxidized to oxalic acid at high temperature, while releasing electrons to reduce Ag ions to Ag atoms. Polyvinylpyrrolidone (PVP) molecules preferentially adsorb on the {100} crystal plane of Ag through carbonyl oxygen atoms, inhibiting the growth rate of the crystal plane. At the same time, PVP-K30 acts as a steric inhibitor to inhibit the aggregation of silver nanoparticles and ensure uniform morphology of nanorods. The Cl in NaCl - With Ag + Formation of [AgCl2] - Complex, reduce Ag + The reduction potential of the nanoparticles slows down the growth of the {111} facets and anisotropic growth dominates. <110> direction, and finally formed a rod-like structure with an aspect ratio of 22.22.

[0026] In some embodiments, the molar ratio of the silver source to 4-aminothiophenol is 1:10.

[0027] In this embodiment, the molar ratio of silver nitrate to PATP ensures that the surface of the silver nanorods is completely covered by PATP molecules, avoiding nonspecific adsorption caused by unmodified areas and improving detection specificity.

[0028] In some embodiments, the temperature for the redox reaction is 150-180°C; and the temperature for the self-assembly reaction is 20-40°C.

[0029] The present application provides an application of a surface-enhanced Raman probe in detecting trace amounts of nitro explosives.

[0030] In some embodiments, the nitro-based explosive comprises TNT.

[0031] In this example, the nitro group of TNT and the amino group of PATP form an azo compound (DMAB) through charge transfer, and its Raman characteristic peak (1078 cm -1 、1385 cm -1 ) intensity is positively correlated with TNT concentration.

[0032] In some embodiments, detecting trace amounts of nitro-based explosives comprises the following steps: K1. The surface-enhanced Raman probe is mixed with a standard analyte gradient solution and a test explosive solution to obtain a corresponding standard analyte group and the test substance; K2. Immerse the cleaned optical fiber end faces in the standard analyte group and the analyte, respectively, and remove and dry them to obtain the corresponding standard analyte optical fiber end face group and the optical fiber end face to be analyzed; K3. Use a fiber optic sensing system to couple laser light to the standard analyte fiber end face set and the end face of the fiber to be analyzed, and collect SERS signals to obtain the Raman spectral characteristic peak intensities of the standard analyte set and the analyte to be analyzed. K4. Establish a concentration-peak intensity standard curve based on the Raman spectral peak intensities of the standard analyte group. Substitute the characteristic peak intensities of the Raman spectroscopy of the analyte into the standard curve to obtain the concentration of the explosive to be tested.

[0033] In this embodiment, the analyte or standard analyte group in step K1 is a TNT methanol solution, and the volume ratio of the TNT methanol solution to AgNRs@PATP is 1:1 to obtain AgNRs@PATP@TNT, generating a "hotspot" signal, which in turn leads to an enhancement of the Raman signal of TNT.

[0034] In this embodiment, the steps for cleaning the optical fiber end face are: stripping the optical fiber with a fiber stripper, then cutting the outer layer of the optical fiber with a fiber cleaver, and finally obtaining a clean and smooth optical fiber end face with a fiber cleaver or an "8"-shaped grinding method; the soaking time in step K2 is 5-10 minutes, and the drying time is 20 seconds. Drying can be accelerated by natural air drying, air flow, or the use of heating equipment to remove residual liquid or solvent.

[0035] In some embodiments, the laser parameters of the fiber optic sensing system are: wavelength of 785±5 nm, power of 6±0.5 mW, and integration time of 4-5 seconds.

[0036] like Figure 1 As shown, the present application provides a fiber optic sensing system, including an optical excitation unit, a fiber optic coupling unit, and a signal acquisition unit; the optical excitation unit includes a laser, a collimator, a first dielectric film reflector, a second dielectric film reflector, and a dichroic mirror arranged in sequence along the optical path, the laser emits 785±5 nm wavelength laser with an output power of 6±0.5 mW; the fiber optic coupling unit includes an objective lens and a three-dimensional precision translation stage, the three-dimensional precision translation stage is used to fix the hard plastic clad optical fiber, and the dichroic mirror reflects the laser to the objective lens and couples it into the optical fiber end face; the signal acquisition unit includes a first long-pass filter, a second long-pass filter, a lens sleeve, a five-axis coupler, and a spectrometer arranged in sequence along the optical path, the cutoff wavelength of the first long-pass filter and the second long-pass filter is 800 nm, and is used to transmit 1140 cm -1 and 1380 cm -1 The Raman signal at the target location is detected and the excitation light is blocked. The positioning accuracy of the three-dimensional precision translation stage is ≤100 nm, which is used to adjust the focus overlap between the fiber end face and the objective lens to optimize the collection efficiency of the surface-enhanced Raman signal.

[0037] The system consists of a laser, optical adjustment components, a fiber coupling unit, and a signal acquisition module. The optical path operates as follows: The laser emits a 785 nm wavelength. The laser beam is first collimated by a collimator. It then passes through two dielectric-coated mirrors to redirect the beam and guide it to the surface of a dichroic mirror. The dichroic mirror reflects the 785 nm laser beam to an objective lens, which focuses the beam onto the end face of a fiber mounted on a three-dimensional precision translation stage. The fiber is clad in hard plastic and its end face is polished using a figure-8 method to ensure a clean and flat surface. When the laser beam is focused onto the fiber end face, the AgNRs@PATP@TNT complex adsorbed on the end face generates a surface-enhanced Raman scattering (SERS) signal in response to the excitation light. The Raman signal, with a wavelength greater than 785 nm, is reflected from the fiber end face and then converted back to parallel light by the objective lens. The reflected Raman signal passes through the dichroic mirror (which transmits wavelengths greater than 800 nm) and then passes through two long-pass filters. The first filter (installed in the lens sleeve) works in conjunction with the second filter to filter out residual Rayleigh scattered light (wavelength ≤ 785 nm) and retain pure Raman signals. The filtered Raman signal is adjusted by the five-axis coupler to adjust the optical path angle and finally introduced into the spectrometer. The spectrometer integration time is set to 4-5 seconds. The collected signal is transmitted to the computer for processing to generate a spectrum containing TNT characteristic peaks (such as 1078cm -1 、1385 cm-1 Through the above optical path design and parameter optimization, rapid, highly sensitive, and highly specific detection of trace TNT was achieved.

[0038] The present invention is further described below through specific examples.

[0039] Example 1 A surface-enhanced Raman probe comprises a silver nanorod and a 4-aminothiophenol molecular layer adsorbed on the surface of the silver nanorod.

[0040] The preparation method of the surface enhanced Raman probe comprises the following steps: S1. Prepare 0.1 g / mL polyvinyl pyrrolidone (PVP-K30) ethylene glycol solution and 80 μL of 0.2 M NaCl ethylene glycol solution, mix the two solutions, and sonicate for 5 min to obtain a mixed solution; prepare 0.125 g / mL silver nitrate (AgNO3) ethylene glycol solution, and add it dropwise to the mixed solution stirred at 160°C at a drop rate of 0.2 ml / min. After reacting for 2 h, cool it down, add an appropriate amount of ethanol to the obtained colloid, centrifuge it at 4000 rpm / min, and separate it to obtain AgNRs, which are silver nanorods; the TEM image of AgNRs is shown in Figure 1. Figure 2 (a) S2. Preparation 10 -5 mol / L PATP ethanol solution, a silver source and 4-aminothiophenol were mixed at a molar ratio of 1:10, and stirred at 250 rpm / min at 25°C for 4 h. The resulting solution was allowed to stand for 0.5 h to allow AgNRs to react completely with PATPA to form the SERS probe AgNRs@PATP; the TEM image of AgNRs@PATP is shown in Figure 2. Figure 2 (b)

[0041] Example 2 A fiber optic sensing system for detecting trace nitro explosives comprises an optical excitation unit, a fiber optic coupling unit, and a signal acquisition unit. The optical excitation unit comprises a laser, a collimator, a first dielectric film reflector, a second dielectric film reflector, and a dichroic mirror, which are sequentially arranged along an optical path. The laser emits 785 nm wavelength laser light with an output power of 6 mW. The fiber optic coupling unit comprises an objective lens and a three-dimensional precision translation stage, which is used to fix a hard plastic-clad optical fiber. The dichroic mirror reflects the laser light toward the objective lens and couples it into the optical fiber end face. The signal acquisition unit comprises a first long-pass filter, a second long-pass filter, a lens sleeve, a five-axis coupler, and a spectrometer, which are sequentially arranged along the optical path. The cutoff wavelength of the first long-pass filter and the second long-pass filter is 800 nm, which is used to transmit 1140 cm -1 and 1380 cm -1The Raman signal at the target location is detected and the excitation light is blocked. The positioning accuracy of the three-dimensional precision translation stage is 100 nm, which is used to adjust the focus overlap between the fiber end face and the objective lens to optimize the collection efficiency of the surface-enhanced Raman signal.

[0042] The system consists of a laser, an optical adjustment component, a fiber coupling unit, and a signal acquisition module. The specific optical path operation process is as follows: the laser emits a laser with a wavelength of 785 nm. The laser beam is first adjusted to parallel light by a collimator, and then the optical path direction is adjusted by two dielectric film reflectors and guided to the surface of a dichroic mirror. The dichroic mirror reflects the 785 nm laser to the objective lens, which focuses the beam onto the end face of an optical fiber fixed to a three-dimensional precision translation stage. The optical fiber adopts a hard plastic cladding structure, and its end face is processed by the "8" figure grinding method to ensure a clean and flat surface. When the laser is focused on the end face of the optical fiber, the AgNRs@PATP@TNT complex adsorbed on the end face generates a surface-enhanced Raman scattering (SERS) signal under the action of the excitation light. The Raman signal, with a wavelength greater than 785 nm, reflects from the fiber end face and is converted back into parallel light by an objective lens. The reflected Raman signal passes through a dichroic mirror and then, in sequence, through two long-pass filters. The first filter (installed in the lens sleeve) works in conjunction with the second filter to remove residual Rayleigh scattered light, preserving the pure Raman signal. The filtered Raman signal is then adjusted for optical path angle by a five-axis coupler and ultimately fed into a spectrometer with an integration time set to 4-5 seconds. The collected signal is then transmitted to a computer for processing, generating a Raman spectrum containing the characteristic peaks of TNT. Through this optical path design and parameter optimization, rapid, highly sensitive, and specific detection of trace amounts of TNT is achieved.

[0043] Example 3 An application of a surface-enhanced Raman probe to detect trace amounts of nitro-based explosives comprises the following steps: K1. The surface enhanced Raman probe obtained in Example 1 was mixed with a standard TNT gradient solution (10 -4 mol / L, 10 - 5 mol / L, 10 -6 mol / L, 10 -7 mol / L, 10 -8 mol / L, 10 -9 mol / L, 10 -10 mol / L) and the TNT solution to be tested were mixed in a volume ratio of 1:1 to obtain the standard analyte group and the analyte to be tested; K2. Use a fiber stripper to strip the optical fiber, then cut the outer layer with a fiber cleaver. Finally, use a fiber cleaver or the "8" grinding method to obtain a clean and smooth fiber end face. Immerse the cleaned fiber end face in the standard analyte set and the analyte for 5 minutes, then remove and dry for 20 seconds to obtain the standard analyte fiber end face set and the fiber end face to be analyzed. K3. Build the fiber optic sensing system of Example 2, and use the fiber optic sensing system to couple the laser to the standard analyte fiber end face group and the fiber end face to be analyzed, and collect SERS signals to obtain the Raman spectrum characteristic peak intensities of the standard analyte group and the analyte; K4. Establish a concentration-peak intensity standard curve based on the Raman spectral peak intensities of the standard analyte group. Substitute the characteristic peak intensities of the Raman spectroscopy of the analyte into the standard curve to obtain the concentration of the explosive to be tested.

[0044] The Raman spectra of TNT, AgNRs@PATP and AgNRs@PATP@TNT are shown in the following order: Figure 3 (a), 3 (b), and 3 (c) illustrate that the embodiments of the present application can effectively detect TNT.

[0045] Comparative Example 1 An application of a surface-enhanced Raman probe for detecting trace amounts of nitro explosives. The other contents are the same as those in Example 3, except that the steps of K2 are to strip the optical fiber with an optical fiber stripper, then cut the outer layer of the optical fiber with an optical fiber cutter, and finally obtain a clean and smooth optical fiber end face using an optical fiber cutter or an "8" grinding method; the cleaned optical fiber end face is immersed in a standard analyte group for 5 minutes, and then taken out and dried for 20 seconds to obtain the corresponding standard analyte optical fiber end face data. Unlike the immersion-drying method of K2, this comparative example uses an immersion method. The comparison results are shown in FIG. Figure 4 As shown, it shows that the dry-immersion method can obtain a stronger SERS signal than the immersion method.

[0046] Comparative Example 2 Testing and Evaluation According to the concentration-peak intensity standard curve established Figure 5 (1141cm -1 ), the concentration of TNT in the test of Example 3 is 1*10 -10 mol / L, and the concentration was detected by HPLC-MS and the result was 1.02*10 -10 mol / L, indicating that the accuracy of the TNT test in the embodiment of the present application is high and the detection limit is low.

[0047] Specificity test: The surface enhanced Raman probe obtained in Example 1 was respectively -8 mol / L TNT solution, 10 -8 mol / L DNT solution, 10-8 mol / L TNP solution was mixed in a volume ratio of 1:1 to obtain the corresponding analyte; the optical fiber was stripped with an optical fiber stripper, and the outer layer of the optical fiber was cut with an optical fiber cutter, and finally a clean and smooth optical fiber end face was obtained using an optical fiber cutter or an "8" grinding method; the cleaned optical fiber end face was immersed in the standard analyte group and the analyte for 5 minutes, and then taken out and dried for 20 seconds to obtain the corresponding analyte optical fiber end face group; the optical fiber sensing system of Example 2 was constructed, and the optical fiber sensing system was used to couple the laser to the standard analyte optical fiber end face group and the optical fiber end face to be analyzed, and the SERS signal was collected to obtain the Raman spectrum characteristic peak intensity of different analytes; the results are shown in FIG. Figure 6 As shown, the test substances obtained in Example 3 and Comparative Example 2 are AgNRs@PATP@TNT, AgNRs@PATP@TNP, and AgNRs@PATP@DNT, respectively. Figure 6 As shown, it is shown that the SERS probe AgNRs@PATP configured in the present invention has good specificity for detecting TNT solution.

[0048] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A surface-enhanced Raman probe, characterized in that: The invention comprises silver nanorods and a 4-aminothiophenol molecular layer adsorbed on the surface of the silver nanorods.

2. A method for preparing a surface-enhanced Raman probe according to claim 1, characterized in that: The following steps are involved: A polymer stabilizer, a halide additive and a silver source are dispersed in an ethylene glycol solvent and subjected to a redox reaction to obtain silver nanorods; The silver nanorods are mixed with 4-aminothiophenol and subjected to a self-assembly reaction to obtain the surface enhanced Raman probe.

3. The method for preparing a surface-enhanced Raman probe according to claim 2, wherein: The polymer stabilizer includes polyvinyl pyrrolidone; the halide additive includes sodium chloride; and the silver source includes silver nitrate.

4. The method for preparing a surface-enhanced Raman probe according to claim 2, wherein: The molar ratio of the silver source to the 4-aminothiophenol is 1:

10.

5. The method for preparing a surface-enhanced Raman probe according to claim 2, wherein: The temperature of the redox reaction is 150-180°C; the temperature of the self-assembly reaction is 20-40°C.

6. Use of the surface-enhanced Raman probe according to claim 1 in detecting trace amounts of nitro explosives.

7. The use according to claim 6, characterized in that The nitro-based explosive includes TNT.

8. The use according to claim 6, characterized in that The following steps are involved: The surface-enhanced Raman probe is mixed with a standard analyte gradient solution and a test explosive solution, respectively, to obtain a standard analyte group and a test explosive; Immerse the cleaned optical fiber end faces in the standard analyte group and the analyte, respectively, and take them out and dry them, thereby obtaining the standard analyte optical fiber end face group and the optical fiber end face to be analyzed; The laser is coupled to the standard analyte fiber end face group and the end face of the fiber to be analyzed by using an optical fiber sensing system, and SERS signals are collected to obtain the Raman spectrum characteristic peak intensities of the standard analyte group and the object to be analyzed respectively; A concentration-peak intensity standard curve is established based on the Raman spectrum peak intensity of the standard analyte group, and the Raman spectrum characteristic peak intensity of the analyte is inserted into the standard curve to obtain the concentration of the explosive to be tested.

9. The use according to claim 8, characterized in that The laser parameters of the optical fiber sensing system are: wavelength of 785±5 nm, power of 6±0.5 mW, and integration time of 4-5 seconds.

10. A fiber optic sensing system for performing the application of claim 9, characterized in that: The invention comprises an optical excitation unit, an optical fiber coupling unit, and a signal acquisition unit; the optical excitation unit comprises a laser (1), a collimator (2), a first dielectric film reflector (3), a second dielectric film reflector (4), and a dichroic mirror (5) arranged in sequence along the optical path; the optical fiber coupling unit comprises an objective lens (6) and a three-dimensional precision displacement stage (7), the three-dimensional precision displacement stage is used to fix the optical fiber (8), and the dichroic mirror (5) reflects the laser to the objective lens (6) and couples it into the end face of the optical fiber (8); the signal acquisition unit comprises a first long-pass filter (9), a second long-pass filter (11), a lens sleeve (10), a five-axis coupler (12), and a spectrometer (13) arranged in sequence along the optical path.

Images