Atmospheric br o radical ultra-high sensitivity online detection system and method

Abstract

This invention relates to the field of atmospheric trace gas detection technology, specifically disclosing an ultra-high sensitivity online detection system and method for atmospheric BrO radicals. The ultra-high sensitivity online detection system for atmospheric BrO radicals includes an optical cavity, a 340 nm ultraviolet light source, an ultraviolet optical fiber, an ultraviolet spectrometer, and a sampling unit. The optical cavity has an inlet and an outlet, and contains an ultraviolet optical resonance region. Ultraviolet light emitted from the ultraviolet light source is reflected multiple times in the ultraviolet optical resonance region and then transmitted into the ultraviolet optical fiber. The ultraviolet optical fiber is used to superimpose all transmitted light in the ultraviolet band and transmit it to the ultraviolet spectrometer. The sampling unit is used to directly input the gas to be measured into the optical cavity, or to selectively remove BrO radicals from the gas to be measured before inputting it into the optical cavity. This invention achieves ultra-high sensitivity online point detection of BrO radicals in the atmosphere. Compared with existing technologies at home and abroad, its BrO detection limit is better than 1 pptv, reaching the sub-pptV level, demonstrating excellent detection performance.

Description

Technical Field

[0001] This invention relates to the field of atmospheric trace gas detection technology, and in particular to an ultra-sensitive online detection system and method for atmospheric BrO radicals. Background Technology

[0002] Reactive halogens are important species in the atmosphere, participating in various atmospheric chemical reactions and playing a vital role in atmospheric chemistry. Bromine monoxide radical (BrO·), as one of the most important molecules among reactive halogens, profoundly influences the global atmospheric environment and climate system; however, its accurate measurement is extremely difficult. Therefore, research on the precise and highly sensitive detection of atmospheric BrO radicals is crucial.

[0003] Currently, the measurement technology of atmospheric BrO radicals is mainly based on the characteristic spectral absorption of BrO radicals. Differential absorption spectroscopy (DOAS) is the most important means of measuring atmospheric tropospheric BrO radicals at home and abroad. The detection limit of atmospheric BrO radicals internationally is about 1 pptv. It is widely used in ground observation, aerial survey and satellite remote sensing. However, differential absorption spectroscopy usually measures the average concentration in an open space range of several kilometers. There is a lack of high-sensitivity point measurement technology and equipment for atmospheric BrO radicals internationally.

[0004] The main challenge in detecting atmospheric BrO radicals lies in the extremely low concentration of atmospheric BrO radicals in the atmosphere, typically only pptV (10⁻⁶). -12 It is on the order of volume concentration, extremely active, and easily depleted. Furthermore, as... Figure 1 As shown, the main absorption peak of BrO radical at 339 nm is very close to the absorption peak of atmospheric formaldehyde (HCHO). If the concentration of atmospheric HCHO is high, it will have a significant cross-interference effect on the spectral measurement of BrO radical. Summary of the Invention

[0005] Based on this, the purpose of this invention is to provide an ultra-sensitive online detection system and method for atmospheric BrO radicals, which realizes ultra-sensitive online point detection of BrO radicals in the atmosphere. Compared with existing technologies at home and abroad, its BrO detection limit is better than 1pptv, reaching the sub-pptV level, and its detection performance is excellent.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an ultra-sensitive online detection system for atmospheric BrO radicals, comprising an optical cavity, a 340 nm ultraviolet light source, an ultraviolet optical fiber, an ultraviolet spectrometer, and a sampling unit. The optical cavity has an inlet and an outlet, and contains an ultraviolet optical resonance region. The ultraviolet light emitted by the ultraviolet light source is reflected multiple times in the ultraviolet optical resonance region and then transmitted into the ultraviolet optical fiber. The ultraviolet optical fiber is used to superimpose all transmitted light in the ultraviolet band and transmit it to the ultraviolet spectrometer. The sampling unit is used to directly input the gas to be measured into the optical cavity, or to selectively remove BrO radicals from the gas to be measured before inputting it into the optical cavity.

[0007] As a further improvement to the above-mentioned solution of the present invention, a first high-reflection mirror and a second high-reflection mirror are arranged opposite to each other in the optical cavity, and the ultraviolet optical resonance region is formed between the first high-reflection mirror and the second high-reflection mirror.

[0008] As a further improvement of the above-mentioned solution of the present invention, the first high-reflection mirror and the second high-reflection mirror are respectively provided with a collimating lens and a converging lens on a side away from each other. The ultraviolet light emitted by the ultraviolet light source is collimated by the collimating lens and enters the ultraviolet optical resonance region. The ultraviolet light is reflected multiple times in the ultraviolet optical resonance region and transmitted through the second high-reflection mirror. The transmitted ultraviolet light enters the ultraviolet optical fiber after passing through the converging lens.

[0009] As a further improvement to the above-mentioned solution of the present invention, an aperture is provided between the first high-reflection mirror and the collimating lens, and an ultraviolet filter is provided between the second high-reflection mirror and the converging lens.

[0010] As a further improvement to the above-mentioned scheme of the present invention, the reflectivity of the first high-reflectivity mirror and the second high-reflectivity mirror at 340 nm is ≥99.965%, and the effective optical path of the constructed ultraviolet optical resonance region should be greater than 2 kilometers.

[0011] As a further improvement to the above-mentioned solution of the present invention, the sampling unit includes an electric three-way reversing valve, a sampling tube, a first pipeline, a second pipeline, a third pipeline, a BrO radical selective cleaner, a sample outlet tube, and a sampling pump; one end of the sampling tube, the first pipeline, and the second pipeline are respectively connected to the three ports of the electric three-way reversing valve, and the other end of the first pipeline is connected to the air inlet of the optical cavity; the other end of the second pipeline is connected to the inlet of the BrO radical selective cleaner; the outlet of the BrO radical selective cleaner is connected to the first pipeline through the third pipeline; one end of the sample outlet tube is connected to the air outlet of the optical cavity, and the other end is connected to the inlet of the sampling pump.

[0012] As a further improvement to the above-described scheme of the present invention, the BrO radical selective remover includes a glass tube and vinyl-modified silica wool filled inside the glass tube, wherein the filling density of the vinyl-modified silica wool is 0.1~0.2 g / cm³. 3The BrO radical selective remover can eliminate BrO radicals without affecting interfering gases such as formaldehyde.

[0013] As a further improvement to the above-mentioned scheme of the present invention, the method for preparing the vinyl-modified quartz wool is as follows: heat-treating quartz wool in an inert atmosphere at 500~600℃, immersing the dried quartz wool in a toluene solution of 2wt%~5wt% vinyltrimethoxysilane for reaction, washing, and drying to obtain vinyl-modified quartz wool.

[0014] As a further improvement to the above-mentioned solution of the present invention, the optical cavity, sampling tube, pipeline one, pipeline two, and pipeline three are all made of PFA material, and the electric three-way reversing valve is fluorinated or the valve core of the electric three-way reversing valve is made of PFA material.

[0015] This invention also provides a method for ultra-sensitive online detection of atmospheric BrO radicals, which employs the aforementioned ultra-sensitive online detection system for BrO radicals, and includes the following steps: S1. Fill the optical cavity with high-purity helium gas and obtain the intensity of helium transmitted light using an ultraviolet spectrometer. ； The optical cavity was filled with high-purity nitrogen gas, and the intensity of nitrogen transmitted light was obtained using an ultraviolet spectrometer. The reflectivity of the ultraviolet optical resonance region can be calculated using the following formula. :

[0016] In the formula: and These are the Rayleigh scattering coefficients for helium and nitrogen, respectively. d 0 represents the length of the ultraviolet optical resonance region; S2. The sampling unit selectively removes BrO radicals from the atmosphere to be measured before inputting it into the optical cavity. A 340 nm ultraviolet light source emits ultraviolet light into the optical resonant region. The ultraviolet light is reflected and transmitted multiple times in the optical resonant region. All transmitted light is superimposed on the ultraviolet fiber and transmitted to the ultraviolet spectrometer. The ultraviolet spectrometer outputs the intensity of the transmitted light. That is, the background spectrum; S3. The sampling unit directly inputs the atmospheric sample into the optical cavity. A 340 nm ultraviolet light source emits ultraviolet light into the optical resonant region. The ultraviolet light is reflected and transmitted multiple times in the optical resonant region. All transmitted light is superimposed on the ultraviolet optical fiber and transmitted to the ultraviolet spectrometer. The ultraviolet spectrometer outputs the intensity of the transmitted light. That is, measuring the spectrum; S4. Calculate the absorption coefficient of BrO radicals according to the following formula. :

[0017] In the formula: The Rayleigh scattering coefficient of the atmosphere; According to the absorption coefficient The concentration of BrO radicals in the atmosphere was calculated by combining the absorption cross section of the 330-345nm ultraviolet band with the standard gas of BrO radicals and using least squares fitting.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention achieves ultra-high sensitivity online point-based detection of BrO radicals in the atmosphere. Compared with existing technologies at home and abroad, its BrO detection limit is better than 1 pptv, reaching the sub-pptV level, demonstrating excellent detection performance. This invention employs an innovative design, utilizing a unique BrO radical selective remover to selectively eliminate BrO radicals. By sequentially measuring the background spectrum and the measured spectrum, it not only eliminates atmospheric formaldehyde and other substances that severely interfere with BrO radical spectral fitting but also simultaneously reduces noise, further enhancing the detection capability of BrO radicals. This invention provides reliable measurement technology support for the study of atmospheric BrO chemistry. Attached Figure Description

[0019] Figure 1 The UV absorption spectra of BrO radical and formaldehyde (HCHO) are shown. Figure 2 A structural diagram of an ultra-sensitive online detection system for atmospheric BrO radicals provided by this invention; Figure 3 The results of the ALLAN variance analysis for the ultra-sensitive online detection system for atmospheric BrO radicals in this embodiment of the invention are shown.

[0020] Figure reference numerals: 1. Optical cavity; 2. 340 nm ultraviolet light source; 3. Ultraviolet fiber; 4. Ultraviolet spectrometer; 5. First high-reflection mirror; 6. Second high-reflection mirror; 7. Collimating lens; 8. Converging lens; 9. Aperture; 10. Ultraviolet filter; 11. Electric three-way reversing valve; 12. Sampling tube; 13. Pipeline 1; 14. Pipeline 2; 15. Pipeline 3; 16. BrO radical selective purifier; 17. Sample outlet tube; 18. Sampling pump; 19. Particulate filter. Detailed Implementation

[0021] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0023] Reference Figure 2 This embodiment proposes an ultra-sensitive online detection system for atmospheric BrO radicals, which includes an optical cavity 1, an ultraviolet light source, a collimating lens 7, an aperture 9, an ultraviolet filter 10, a converging lens 8, an ultraviolet optical fiber 3, an ultraviolet spectrometer 4, and a sampling unit.

[0024] The optical cavity 1 is a sealed cavity with an air inlet and an air outlet. A first high-reflectivity mirror 5 and a second high-reflectivity mirror 6 are respectively installed at both ends of the optical cavity 1, thereby forming an optical resonance region between the first high-reflectivity mirror 5 and the second high-reflectivity mirror 6. The distance between the first high-reflectivity mirror 5 and the second high-reflectivity mirror 6 should be no less than 70 cm, preferably 0.9~1 m, and its length should be less than the radius of curvature of the first high-reflectivity mirror 5 and the second high-reflectivity mirror 6. The effective optical path of the formed optical resonance region should be as high as possible, with a minimum of no less than 2 km, to achieve ultra-high sensitivity detection of atmospheric BrO radicals. In this embodiment, the distance between the first high-reflectivity mirror 5 and the second high-reflectivity mirror 6 is 0.94 m. The optical cavity 1 is made of highly inert PFA material to minimize sampling loss. The reflectivity of the first high-reflectivity mirror 5 and the second high-reflectivity mirror 6 at 340 nm should be no less than 99.965%, preferably better than 99.97%.

[0025] An ultraviolet (UV) light source 2 is positioned on one side of the first high-reflectivity mirror 5. A collimating lens 7 and an aperture 9 are sequentially arranged between the UV light source and the first high-reflectivity mirror 5. The UV light emitted from the UV light source is collimated by the collimating lens 7 and then enters the optical cavity 1 through the first high-reflectivity mirror 5. The UV beam undergoes multiple reflections and absorptions within the optical resonance region. Each time the light is reflected, a portion is transmitted through the second high-reflectivity mirror 6. In this embodiment, the UV light source is a 340 nm LED light source, using a high-power single-core UV LED with a high-efficiency light-emitting chip material. Precise temperature control is implemented, maintaining the temperature at 20±0.01℃. A high-stability constant current power supply is used to ensure the stability of the output spectrum. High-power current is used during operation to maximize the light intensity emitted by the light source. In this embodiment, the collimating lens 7 is selected as a lens with high UV transmittance or an off-axis parabolic mirror with high UV reflectivity to maximize optical efficiency and minimize signal loss.

[0026] An ultraviolet filter 10 and a converging lens 8 are sequentially disposed outside the second high-reflectivity mirror 6. Transmitted light passes through the ultraviolet filter 10 and the converging lens 8 into the ultraviolet fiber 3, and then is transmitted to the ultraviolet spectrometer 4. The light received by the ultraviolet spectrometer 4 is the sum of all transmitted light. In this embodiment, the ultraviolet filter 10 is selected from a lens with high ultraviolet transmittance or an off-axis parabolic mirror with high ultraviolet reflectance to maximize optical efficiency and minimize signal loss. The converging lens 8 is also selected from a lens with high ultraviolet transmittance or an off-axis parabolic mirror with high ultraviolet reflectance to maximize optical efficiency and minimize signal loss.

[0027] The sampling unit is used to deliver the air to be measured into the optical cavity 1. The sampling unit includes a sampling tube 12, a particulate filter 19, an electrically operated three-way reversing valve 11, a BrO radical selective purifier 16, and a sampling pump 18. The sampling tube 12 is connected to the inlet of the particulate filter 19. The outlet of the particulate filter 19 is connected to one port of the electrically operated three-way reversing valve 11 via a pipeline. The other two ports of the electrically operated three-way reversing valve 11 are connected to the inlet of the BrO radical selective purifier 16 and the air inlet of the optical cavity 1, respectively, via pipelines. The outlet of the BrO radical selective purifier 16 is connected to the air inlet of the optical cavity 1 via a pipeline. The inlet of the sampling pump 18 is connected to the air outlet of the optical cavity 1 via a sample outlet tube 17. The electrically operated three-way reversing valve 11 is fluorinated or its valve core is made of PFA material to minimize the impact on the measured gas. The sampling tube 12, all pipelines, the particulate filter 19, and connectors are all made of highly inert PFA material to minimize sampling losses.

[0028] In this embodiment, the BrO radical selective remover 16 can efficiently and selectively remove highly reactive BrO radicals without interfering with the concentration of other substances such as formaldehyde. The BrO radical selective remover in this embodiment includes a glass tube and vinyl-modified silica wool filled inside the glass tube. The filling density of the vinyl-modified silica wool is 0.1~0.2 g / cm³. 3 The specific production method is as follows: (1) Substrate pretreatment (enhancing surface silanol density) High-purity quartz fiber cotton (SiO2 content ≥ 99.95%, specific surface area approximately 1-2 m²) 2 / g) is placed in a muffle furnace and heated to 550℃ at a heating rate of 5-10℃ / min, and kept at a constant temperature for 2.5 hours under a nitrogen flow to remove organic impurities. This causes partial hydrolysis and breakage of the silicon-oxygen bridge bonds on the quartz surface, generating high-density, uniform isolated silanol groups (Si-OH) and twin silanol groups, providing the maximum grafting density for subsequent silanization.

[0029] (2) Vinyl functionalization modification (anhydrous / micro-water control is key) A 3.0 wt% vinyltrimethoxysilane solution was prepared using anhydrous toluene (dried to <50 ppm moisture content via molecular sieve). Pretreated quartz wool was immersed in the solution, and the reaction was refluxed at 80°C for 5 hours under nitrogen protection. Thirty minutes after the start of the reaction, 0.1 vol% ultrapure water (based on toluene volume) was added dropwise to the system to catalyze the hydrolysis and condensation of the silane. However, the total amount was controlled to prevent the initiation of bulk liquid polymerization, ensuring the formation of a vinyl coating of monolayer or oligolayer (<5 nm thickness) on the quartz surface.

[0030] Post-treatment: The product was ultrasonically cleaned twice each with toluene, anhydrous ethanol, and deionized water, and finally dried at 120°C under vacuum for 3 hours to obtain vinyl-modified quartz wool.

[0031] (3) Filling and aging (eliminating the physical adsorption sites of HCHO) Vinyl-modified quartz wool was uniformly filled into silanized glass tubes, with the filling density precisely controlled at 0.1~0.2 g / cm³. 3 After filling, air containing 5 ppm HCHO and 50% RH humidity was introduced, and the mixture was equilibrated at 25°C for 12 hours. This process utilized the pre-occupation of non-specific physical adsorption active sites on the inner wall of the glass tube and the surface of the material by HCHO to establish an adsorption-desorption dynamic equilibrium. After this treatment, HCHO exhibited extremely high penetration through the separator during the actual measurement process.

[0032] Before using this system, calibration is required. Specifically, the reflectivity curves of the first high-reflectivity mirror 5 and the second high-reflectivity mirror 6 as a function of wavelength must be calibrated. The effective absorption optical path can be calculated based on this data, which is a necessary parameter for spectral fitting. The calibration steps are as follows: Optical cavity 1 was sequentially filled with high-purity helium (99.999%) and nitrogen (99.999%). After the spectrum stabilized, the corresponding transmitted light intensity was recorded using an ultraviolet spectrometer 4. I He (λ) , I N2 (λ) The effective reflectivity of a high-reflectivity mirror can be calculated according to equation (1). :

[0033] in: I He (λ) and I N2 (λ) These represent the spectral intensities after the optical cavity is filled with helium and nitrogen, respectively. and These are the Rayleigh scattering coefficients for helium and nitrogen, respectively.d 0 represents the distance between the first high-reflection mirror 5 and the second high-reflection mirror 6. d 0 = 0.94 m.

[0034] After system calibration, actual measurements can be performed. First, the electric three-way reversing valve 11 is set to pass through the BrO radical selective purifier 16 before entering the optical cavity 1. The gas in the optical cavity 1 does not contain BrO radicals. The ultraviolet spectrometer 4 detects the absorption spectrum of the gas other than BrO radicals, i.e., the background spectrum. The ultraviolet spectrometer outputs the transmitted light intensity. .

[0035] Next, set the electric three-way reversing valve 11 to directly connect to the optical cavity 1. After stabilization, the ultraviolet spectrometer 4 detects the absorption spectrum of the atmosphere to be measured, i.e., the measurement spectrum, and outputs the intensity of transmitted light. .

[0036] The absorption coefficient obtained from measurements in this band is calculated using the following formula. :

[0037] The Rayleigh scattering coefficient of the atmosphere. The effective reflectivity of the first high-reflectivity mirror 5 and the second high-reflectivity mirror 6 was obtained through calibration.

[0038] Calculated absorption coefficient This can be viewed as the absorption of n types of gases in this wavelength band. Linear superposition:

[0039] It is the total gas absorption. It is the first i Gas at wavelength Absorption at the site, It is the first i Gas at wavelength Reference absorption cross section at the location, It is the first i Medium gas concentration.

[0040] According to the absorption coefficient The concentration of BrO radicals in the atmosphere was calculated using least-squares fitting by combining the absorption cross-section of the 330-345 nm ultraviolet band with that of the BrO radical standard gas. The absorption cross-section of the BrO radical standard gas was obtained by convolving the high-resolution absorption cross-section from an internationally recognized absorption spectral database with the instrument function of the ultraviolet spectrometer used.

[0041] In a field test, the ultra-sensitive online detection system for atmospheric BrO radicals constructed in this invention achieved a detection limit of 0.58 pptV for BrO radicals (based on ALLAN variance analysis, such as...). Figure 3 As shown in the figure, the measurement error is less than 15% and the precision is less than 3%.

[0042] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A highly sensitive online detection system for atmospheric BrO radicals, characterized in that, It includes an optical cavity (1), a 340 nm ultraviolet light source (2), an ultraviolet fiber (3), an ultraviolet spectrometer (4), and a sampling unit; the optical cavity (1) has an air inlet and an air outlet, and an ultraviolet optical resonance region is located inside the optical cavity (1); the ultraviolet light emitted by the ultraviolet light source is reflected multiple times in the ultraviolet optical resonance region and then transmitted into the ultraviolet fiber (3); the ultraviolet fiber (3) is used to superimpose all the transmitted light in the ultraviolet band and transmit it to the ultraviolet spectrometer (4); the sampling unit is used to directly input the gas to be measured into the optical cavity (1), or to selectively remove BrO free radicals from the gas to be measured before inputting it into the optical cavity (1).

2. The ultra-sensitive online detection system for atmospheric BrO radicals according to claim 1, characterized in that, The optical cavity (1) is provided with a first high-reflection mirror (5) and a second high-reflection mirror (6) arranged opposite to each other, and the ultraviolet optical resonance region is formed between the first high-reflection mirror (5) and the second high-reflection mirror (6).

3. The ultra-sensitive online detection system for atmospheric BrO radicals according to claim 2, characterized in that, The first high-reflection mirror (5) and the second high-reflection mirror (6) are respectively provided with a collimating lens (7) and a converging lens (8) on one side away from each other. The ultraviolet light emitted by the ultraviolet light source is collimated by the collimating lens (7) and enters the ultraviolet optical resonance region. The ultraviolet light is reflected multiple times in the ultraviolet optical resonance region and transmitted through the second high-reflection mirror (6). The transmitted ultraviolet light enters the ultraviolet optical fiber (3) after passing through the converging lens (8).

4. The ultra-sensitive online detection system for atmospheric BrO radicals according to claim 3, characterized in that, An aperture (9) is provided between the first high-reflection mirror (5) and the collimating lens (7), and an ultraviolet filter (10) is provided between the second high-reflection mirror (6) and the converging lens (8).

5. The ultra-sensitive online detection system for atmospheric BrO radicals according to claim 2, characterized in that, The reflectivity of the first high-reflectivity mirror (5) and the second high-reflectivity mirror (6) at 340 nm is ≥99.965%.

6. The ultra-sensitive online detection system for atmospheric BrO radicals according to claim 1, characterized in that, The sampling unit includes an electric three-way reversing valve (11), a sampling tube (12), a first pipeline (13), a second pipeline (14), a third pipeline (15), a BrO radical selective cleaner (16), a sample outlet tube (17), and a sampling pump (18). One end of the sampling tube (12), the first pipeline (13), and the second pipeline (14) are respectively connected to the three ports of the electric three-way reversing valve (11). A particulate filter (19) is installed on the sampling tube (12). The other end of the first pipeline (13) is connected to the air inlet of the optical cavity (1). The other end of the second pipeline (14) is connected to the inlet of the BrO radical selective cleaner (16). The outlet of the BrO radical selective cleaner (16) is connected to the first pipeline (13) through the third pipeline (15). One end of the sample outlet tube (17) is connected to the air outlet of the optical cavity (1), and the other end is connected to the inlet of the sampling pump (18).

7. The ultra-sensitive online detection system for atmospheric BrO radicals according to claim 6, characterized in that, The BrO radical selective remover (16) includes a glass tube and vinyl-modified silica wool filled inside the glass tube, the filling density of which is 0.1~0.2 g / cm³. 3 .

8. The ultra-sensitive online detection system for atmospheric BrO radicals according to claim 7, characterized in that, The method for preparing the vinyl-modified quartz wool is as follows: heat-treating quartz wool in an inert atmosphere at 500~600℃, immersing the dried quartz wool in a toluene solution of 2wt%~5wt% vinyltrimethoxysilane for reaction, washing, and drying to obtain vinyl-modified quartz wool.

9. The ultra-sensitive online detection system for atmospheric BrO radicals according to claim 6, characterized in that, The optical cavity, sampling tube (12), pipeline one (13), pipeline two (14), and pipeline three (15) are all made of PFA material. The electric three-way reversing valve (11) is fluorinated or the valve core of the electric three-way reversing valve (11) is made of PFA material.

10. A highly sensitive online detection method for atmospheric BrO radicals, characterized in that, It employs the BrO radical ultra-sensitive online detection system as described in any one of claims 1-9, which includes the following steps: S1. Fill the optical cavity (1) with high-purity helium gas, and obtain the intensity of helium transmitted light by an ultraviolet spectrometer (4). ； The optical cavity (1) is filled with high-purity nitrogen gas, and the intensity of nitrogen transmitted light is obtained by an ultraviolet spectrometer (4). The reflectivity of the ultraviolet optical resonant region is calculated according to the following formula. : In the formula: and These are the Rayleigh scattering coefficients for helium and nitrogen, respectively. d 0 represents the length of the ultraviolet optical resonant region; S2. After selectively removing BrO radicals from the atmosphere to be measured by the sampling unit, the light is input into the optical cavity (1). The 340nm ultraviolet light source (2) emits ultraviolet light into the optical resonance region. The ultraviolet light is reflected and transmitted multiple times in the optical resonance region. The ultraviolet fiber (3) superimposes all the transmitted light and transmits it to the ultraviolet spectrometer (4). The ultraviolet spectrometer (4) outputs the intensity of the transmitted light. ; S3. The atmospheric sample is directly input into the optical cavity (1) through the sampling unit. The 340 nm ultraviolet light source (2) emits ultraviolet light into the optical resonance region. The ultraviolet light is reflected and transmitted multiple times in the optical resonance region. The ultraviolet fiber (3) superimposes all the transmitted light and transmits it to the ultraviolet spectrometer (4). The ultraviolet spectrometer (4) outputs the intensity of the transmitted light. ; S4. Calculate the absorption coefficient of BrO radicals according to the following formula. : In the formula: The Rayleigh scattering coefficient of the atmosphere; According to the absorption coefficient The concentration of BrO radicals in the atmosphere was calculated by combining the absorption cross section of the 330-345nm ultraviolet band with the standard gas of BrO radicals and using least squares fitting.

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