High-sensitivity miniaturized HOx free radical accurate measurement device and method

Abstract

The invention discloses a high-sensitivity miniaturized HOx free radical accurate measurement device and method, and relates to the technical field of atmospheric environment detection and automatic control, and the device is composed of a free radical generation and removal device, a light source module, longitudinal HOx double cavities, a gas distribution module and a collection and control system. The free radical generation and removal device can generate HOx free radicals or remove OH free radicals; the light source module can emit laser which enables OH free radicals to generate fluorescence and transmit the laser into the longitudinal HOx double-cavity; the longitudinal HOx double cavities are used for exciting OH free radicals to generate a large amount of fluorescence and collecting and converting the fluorescence into electric signals; the gas distribution module is used for injecting gas in the device and maintaining the flowing state of gas flow; and the control and acquisition system is used for controlling automatic operation and data acquisition and processing of the device. The device has the advantages of being high in detection sensitivity, small in size and capable of rapidly obtaining and removing OH free radical measurement interference, rapid calibration of similar concentration can be conducted on the actual HOx concentration in the actual measurement environment, accurate spectrum determination can be conducted on the laser wavelength, and therefore high-sensitivity accurate measurement of HOx free radicals is achieved.

Description

Technical Field

[0001] The present invention relates to the field of atmospheric environment detection and automated control technology, and in particular to a highly sensitive and miniaturized HOx free radical precision measurement device and method. Background Art

[0002] Atmospheric oxidation capacity is one of the key factors affecting regional pollution, global climate change and atmospheric ecological environment. The atmospheric oxidation of gaseous pollutants is the driving force for the formation of secondary pollution. Free radicals contribute more than 80% to the atmospheric oxidation capacity. The atmospheric oxidation capacity in the troposphere is mainly provided by the photochemical chain reaction process composed of HOx radicals (OH radical and HO2 radical) during the day, which eventually leads to atmospheric complex pollution characterized by haze and ozone. Therefore, it is particularly important to accurately measure the concentration of HOx radicals in the atmosphere. Laser-induced fluorescence technology has gradually become the main technology for measuring HOx radicals in the field due to its advantages of small background stray light, long fluorescence lifetime, high system detection sensitivity, and small spectral interference. Laser-induced fluorescence instrument is composed of four core components: laser emission unit, low-pressure fluorescence detection cavity, high-sensitivity photomultiplier tube, and standard concentration calibration module. The instrument uses low-pressure expansion sampling technology to collect atmospheric through the micro-pore at the top of the low-pressure fluorescence detection cavity. When the gas sample passes through the micro-pore, it will expand rapidly and be injected downward into the low-pressure fluorescence detection cavity. At this time, the laser beam irradiates the expanded gas sample to excite the OH radical to produce characteristic fluorescence. The detection system captures the fluorescence signal through the photomultiplier tube, uses the method of laser wavelength deviating from the fluorescence excitation band to distinguish the background signal of the instrument, and uses the quantitative relationship established by the standard concentration calibration module to ultimately realize the determination of the concentration of OH radicals. HO2 radicals are indirectly measured by converting them into OH radicals through the NO conversion method. First, due to the low concentration of HOx radicals in actual atmosphere, the conventional single fluorescence excitation method cannot effectively capture the changes in the concentration of HOx radicals when the concentration is very low (such as winter or night). Second, the detection sensitivity of the laser-induced fluorescence instrument for HOx radicals will change slightly over time due to the influence of the actual environment, which will cause system bias in the measurement. Third, due to the fact that the concentration of OH radicals in the actual atmosphere is much lower than that of HO2 radicals, conventional HOx radical standard sources can only produce a known amount of OH radicals and HO2 radicals, and can only adjust the concentration of HOx radicals within a small range. It cannot be calibrated according to the actual concentration of HOx radicals in the actual atmosphere. The response of the system to the large range of HOx radical concentration changes may have unknown nonlinearities, which also leads to additional system bias. Fourth, the interference problem in the measurement of OH radicals by laser-induced fluorescence technology has been proven to exist widely, especially in forest areas. Since most of these interferences cannot be quantitatively deducted, this leads to different degrees of bias in the measurement of OH radicals by laser-induced fluorescence technology.Fifth, laser-induced fluorescence instrument is usually equipped with an additional laser wavelength calibration device for peak locking of fluorescence spectrum, the response peak of photomultiplier tube in the laser wavelength calibration device and the response peak of photomultiplier tube in the low-pressure fluorescence detection cavity have a certain deviation, which leads to a slight decrease in the detection sensitivity of the instrument and an additional system deviation due to the different synchronization of the sensitivity changes of the two, and also increases the complexity of the instrument itself. Finally, due to the complex composition and gas expansion design requirements of the laser-induced fluorescence instrument, the instrument is relatively large in size, which is not convenient for placement and movement measurement. SUMMARY

[0003] In order to overcome the defects in the prior art, the present application provides a high-sensitivity miniaturized HOx free radical precision measurement device and method for realizing high-sensitivity and precise measurement of HOx free radicals.

[0004] In order to achieve the above purpose, the present application adopts the following technical solutions, comprising:

[0005] A high-sensitivity miniaturized HOx free radical precision measurement device, the device comprising: a free radical generation and removal device, a light source module, a longitudinal HOx double cavity, a gas distribution module, an acquisition and control system;

[0006] The free radical generation and removal device is used for generating HOx free radicals or removing OH free radicals, and is installed at the top end of the longitudinal HOx double cavity;

[0007] The light source module is used for emitting laser that makes OH free radicals produce fluorescence and transmitting to the longitudinal HOx double cavity;

[0008] The longitudinal HOx double cavity is used for laser exciting OH free radicals to produce fluorescence, and collecting and converting the fluorescence into an electrical signal;

[0009] The gas distribution module is used for injecting gas in the device and maintaining the flow state of the gas flow;

[0010] The acquisition and control system is used for monitoring and controlling the working state of the free radical generation and removal device and the gas distribution module, and collecting and processing the fluorescence photoelectric signal output by the longitudinal HOx double cavity.

[0011] Preferably, the radical generation and scavenging device comprises: a quartz flow tube for OH radical generation or scavenging, a base for mounting the quartz flow tube and related components, a mercury lamp for emitting ultraviolet light to photolyze oxygen and water contained in the humid synthetic air to generate HOx radicals, a mercury lamp mounting seat for mounting the mercury lamp and related components, a front connecting light cylinder for connecting the mercury lamp mounting seat and the base, a photodiode for detecting the intensity of ultraviolet light, a photodiode mounting cylinder for mounting the photodiode and related components, and a rear connecting light cylinder for connecting the photodiode mounting cylinder and the base.

[0012] The mercury lamp, a mercury lamp light collimation lens, a movable grating plate, and a fixed grating plate are sequentially arranged in the front connecting light cylinder along the direction of propagation of ultraviolet light, wherein the movable grating plate cooperates with the fixed grating plate to adjust the intensity of light emitted by the mercury lamp into the quartz flow tube.

[0013] A band-pass filter, a focusing lens, and a photodiode are sequentially arranged in the rear connecting light cylinder along the direction of propagation of ultraviolet light.

[0014] The quartz flow tube is used for injecting humid synthetic air. A through hole is formed around the position of the quartz flow tube above the light path of ultraviolet light, for a capillary dispensing needle to extend into the quartz flow tube, and the capillary dispensing needle is used for injecting propane gas into the quartz flow tube. The bottom of the quartz flow tube is provided with a gas outlet for gas outflow.

[0015] Preferably, the longitudinal HOx double cavity comprises: two fluorescence excitation cavities installed in an upper-lower superposition manner for exciting OH radicals to generate fluorescence, a sampling nozzle for sampling gas in the radical generation and scavenging device into the upper fluorescence excitation cavity, a laser collimation lens for collimating laser light emitted by a light source module, a plane mirror and an off-axis parabolic mirror for turning the collimated laser beam into the lower fluorescence excitation cavity and performing secondary collimation, a laser energy meter for measuring the energy of laser light emitted from the lower fluorescence excitation cavity, and a protective gas annular injection tube and a conversion gas annular injection tube for respectively injecting nitrogen and nitric oxide into the longitudinal HOx double cavity.

[0016] The upper and lower fluorescence excitation cavities are symmetrically installed on the left and right sides; the protective gas annular injection pipe is installed at the lower part of the sampling nozzle, and the conversion gas annular injection pipe is installed between the upper and lower fluorescence excitation cavities; a plurality of small holes are formed in the lower part of the circumference of the protective gas annular injection pipe, and a plurality of small holes are formed in the inner side of the circumference of the conversion gas annular injection pipe; the diameter of the conversion gas annular injection pipe is greater than that of the protective gas annular injection pipe; the bottom of the lower fluorescence excitation cavity is connected with a vacuum pump; the laser collimating lens is installed at the light inlet of the upper fluorescence excitation cavity; the plane mirror is installed at the light outlet of the upper fluorescence excitation cavity; the off-axis parabolic mirror is installed at the light inlet of the lower fluorescence excitation cavity; and the laser energy meter is installed at the light outlet of the lower fluorescence excitation cavity.

[0017] Preferably, the single fluorescence excitation cavity comprises: a fluorescence cavity body, a photomultiplier tube for detecting fluorescence intensity, a band-pass filter two, an incident end light arm for reducing stray light when the laser beam is incident, an exit end light arm for reducing stray light when the laser beam is emitted, an incident end convex cylindrical mirror and an exit end convex cylindrical mirror for deflecting the collimated laser beam, an incident end concave cylindrical mirror and an exit end concave cylindrical mirror for making the laser beam reflect back and forth multiple times, a front concave spherical mirror and a rear concave spherical mirror for reflecting and focusing the fluorescence, and a concave spherical lens for collimating the fluorescence reflected by the front concave spherical mirror and the rear concave spherical mirror.

[0018] The fluorescence cavity body is a left-right symmetrical square hollow structure, and the left and right sides are respectively provided with an incident end light arm and an exit end light arm; the incident end light arm and the exit end light arm are symmetrical structures, and each of the end faces of the fluorescence cavity body outside has a quartz window piece; and each of the interiors is provided with two tapered diaphragms, and the large opening of the diaphragm faces inward, and the small opening faces outward.

[0019] The incident end concave cylindrical mirror and the exit end concave cylindrical mirror are symmetrical structures, and are respectively installed on the left and right sides inside the fluorescence cavity body.

[0020] The front concave spherical mirror and the rear concave spherical mirror are respectively installed on the front and rear sides inside the fluorescence cavity body, the focal length of the front concave spherical mirror is greater than twice the focal length of the rear concave spherical mirror, the focal point of the rear concave spherical mirror is located at the center of the fluorescence cavity body, and a through hole is formed in the center of the rear concave spherical mirror; and the front concave spherical mirror, the rear concave spherical mirror, the concave spherical lens, the band-pass filter two and the photomultiplier tube are coaxially installed in sequence.

[0021] Preferably, the gas distribution module provides the device with the following gases.

[0022] The dry synthetic air is injected into the water bottle group through a first flowmeter to become humidified synthetic air, the humidified synthetic air is mixed with dry synthetic air flowing through a second flowmeter to become humidified synthetic air with adjustable water vapor concentration, the humidified synthetic air is mixed with carbon monoxide gas flowing through a third flowmeter to become humidified synthetic air, and the humidified synthetic air is injected into a blowing pipe through a temperature and humidity sensor;

[0023] The first nitrogen gas is injected into a communication space between the mercury lamp and the photodiode through a fourth flowmeter;

[0024] The second nitrogen gas is injected into the top of the sampling gas flow from a protective gas annular injection pipe through a fifth flowmeter;

[0025] The propane gas is injected into the quartz flow tube through a sixth flowmeter;

[0026] The nitrogen monoxide gas is injected into the middle of the sampling gas flow from a conversion gas annular injection pipe through a seventh flowmeter;

[0027] The air pump is connected to the quartz flow tube bottom through an eighth flowmeter to make the quartz flow tube generate downward flow.

[0028] Preferably, the collection and control system comprises an ozone analyzer for measuring the ozone concentration in the gas flowing out of the quartz flow tube bottom, a single-chip microcomputer for controlling all electrical elements in the device and collecting the temperature and humidity sensor and photodiode signals, and an industrial computer for receiving the signals of the laser energy meter and the two photomultiplier tubes in the fluorescence excitation cavities and controlling and reading the single-chip microcomputer.

[0029] Preferably, the light source module comprises a laser for emitting laser light for exciting OH radical fluorescence, an optical fiber for transmitting the laser light, and a coupling lens for focusing and coupling the laser light into the optical fiber.

[0030] The application further provides a high-sensitivity miniaturized HOx radical precision measurement method, which is applied to the high-sensitivity miniaturized HOx radical precision measurement device, and the method for capturing the HOx radical concentration change trend is as follows:

[0031] Three measurement states are set:

[0032] Measurement state one: the output wavelength of the laser is locked at the fluorescence excitation peak value of the OH radical, the sixth flowmeter is closed to stop the injection of the propane gas, during the period, the average value of the signal measured by the upper fluorescence excitation cavity is S(OH)1, the average value of the signal measured by the lower fluorescence excitation cavity is S(HO2)1, and the average value of the signal measured by the laser energy meter is P1, and this state is maintained for t1 time;

[0033] Measurement state two: the output wavelength of the laser is locked at the fluorescence excitation peak of OH radical, the sixth flow meter is turned on to inject propane into the quartz flow tube, the propane removes the OH radical in the ambient atmosphere, during this period, the average value of the signal measured by the upper fluorescence excitation cavity is S(OH)2, the average value of the signal measured by the lower fluorescence excitation cavity is S(HO2)2, and the average value of the signal measured by the laser energy meter is P2, this state is maintained for t2 time;

[0034] Measurement state three: the output wavelength of the laser is adjusted to be far away from the fluorescence excitation peak of OH radical, the sixth flow meter is turned off to stop the injection of propane, at this time, the laser does not produce fluorescence with the OH radical, during this period, the average value of the signal measured by the upper fluorescence excitation cavity is S(OH)3, the average value of the signal measured by the lower fluorescence excitation cavity is S(HO2)3, and the average value of the signal measured by the laser energy meter is P3, this state is maintained for t3 time;

[0035] In actual measurement, the three measurement states are switched in turn, and in the three measurement states, the position of the moving grating plate is adjusted so that the intensity of the violet light detected by the photodiode is zero, that is, the ultraviolet light emitted by the mercury lamp is completely blocked by the moving grating plate and the fixed grating plate;

[0036] The method for capturing the change trend of the concentration of OH radical is as follows:

[0037] Firstly, in the measurement state one, the ambient atmosphere is pumped into the quartz flow tube, and then is pumped into the upper and lower fluorescence excitation cavities by the sampling nozzle, at this time, the signal S(OH)1 measured by the upper fluorescence excitation cavity is the sum of the real fluorescence signal of atmospheric OH, the OH interference signal and the background signal of the upper fluorescence excitation cavity, and the average value of the signal measured by the laser energy meter is P1 during this period;

[0038] Then, in the measurement state two, the propane is pumped into the quartz flow tube to remove the OH radical, at this time, the signal S(OH)2 measured by the upper fluorescence excitation cavity is the sum of the OH interference signal and the background signal of the upper fluorescence excitation cavity, and the average value of the signal measured by the laser energy meter is P2 during this period;

[0039] Finally, in the measurement state three, the laser does not produce fluorescence with the OH radical, at this time, the signal S(OH)3 measured by the upper fluorescence excitation cavity is the background signal of the upper fluorescence excitation cavity, and the average value of the signal measured by the laser energy meter is P3 during this period;

[0040] The change trend of S(OH)2-S(OH)3 is the change trend of the real concentration of atmospheric OH radical;

[0041] The change trend of S(OH)2-S(OH)3 is the change trend of the OH interference signal.

[0042] The method to capture the trend of HO2 radical concentration is:

[0043] First, in measurement state 1, ambient air is drawn into the quartz flow tube and then into the upper and lower fluorescence excitation chambers by the sampling nozzle 2. Atmospheric HO2 free radicals are partially converted into OH free radicals by NO between the upper and lower fluorescence excitation chambers. At this time, the signal S(HO2)1 measured by the lower fluorescence excitation chamber is the sum of the fluorescence signal of atmospheric HO2 converted to OH, the background signal of the lower fluorescence excitation chamber, the true fluorescence signal of atmospheric OH, and the OH interference signal. During this period, the average value of the signal measured by the laser energy meter is P1;

[0044] Then, in the second measurement state, propane is drawn into the quartz flow tube to remove the OH radicals. At this time, the signal S(HO2)2 measured by the lower fluorescence excitation cavity is the atmospheric HO 2转化的 The sum of the fluorescence signal of OH, the background signal of the lower fluorescence excitation chamber and the interference signal of OH. The average value of the signal measured by the laser energy meter during this period is P2;

[0045] Finally, in measurement state three, the laser intersects with the OH radical and does not produce fluorescence. At this time, the signal S(HO2)3 measured by the lower fluorescence excitation cavity is the background signal of the lower fluorescence excitation cavity. During this period, the average value of the signal measured by the laser energy meter is P3.

[0046] The changing trend of is the changing trend of the real concentration of atmospheric HO2 radicals; where k is the ratio of the detection sensitivities of the upper and lower fluorescence excitation cavities.

[0047] The present invention also provides a highly sensitive and miniaturized HOx free radical precision measurement method, which is applied to the aforementioned highly sensitive and miniaturized HOx free radical precision measurement device, and utilizes the photomultiplier tube itself to perform peak locking of the fluorescence spectrum line, specifically in the following manner:

[0048] Close the humidified synthetic air and carbon monoxide gas injected into the blowpipe, and close the propane gas injected into the quartz flow tube;

[0049] Adjust the position of the movable grating plate so that the intensity of the ultraviolet light emitted by the mercury lamp detected by the photodiode reaches the highest level. At this time, the ultraviolet light will photolyze the water vapor in the ambient atmosphere, thereby generating OH free radicals.

[0050] Then, the light source module begins to adjust the wavelength of the emitted laser within a certain range. At this time, the fluorescence signal detected by the photomultiplier tube of the upper fluorescence excitation cavity also changes accordingly. When the scan is completed, the wavelength of the laser emitted by the light source module is positioned to the position where the fluorescence signal is highest.

[0051] The application further provides a computer program product comprising computer programs / instructions which, when executed by a processor, implement the high-sensitivity miniaturized HOx radical precision measurement method.

[0052] The application has the advantages that:

[0053] (1) The application provides a high-sensitivity miniaturized HOx radical precision measurement device, which can capture the trend of HOx radical concentration change in a lower HOx radical concentration environment, quickly obtain the detection sensitivity of the instrument at multiple different times in a day, and output HOx radicals similar to the actual HOx radical concentration in the local environment during calibration to reduce system measurement error. In addition, the use of efficient OH radical removal technology combined with a calibration device can accurately remove unknown interference signals, and the photomultiplier tube itself can be used to lock the peak of the fluorescence spectrum, thereby improving the response sensitivity and measurement accuracy of the laser-induced fluorescence instrument for measuring HOx radicals. Meanwhile, a compact structure design and a one-machine multi-purpose design concept are used to reduce the overall volume of the device, making the application convenient to place and move.

[0054] (2) The fluorescence excitation cavity of the device adopts an optical structure combining two convex cylindrical mirrors and two concave cylindrical mirrors, realizes multiple reflections of laser, and the central axis of the multiple reflection path of the laser is tangent to the center of rotation of the fluorescence excitation cavity, which makes the multiple fluorescence excitation points of the laser on the sampling gas flow near the center of the fluorescence excitation cavity, thereby significantly enhancing the fluorescence intensity after repeated excitation.

[0055] (3) The fluorescence collection lens group of the fluorescence excitation cavity of the device adopts a reflective structure, which has a larger light receiving surface and a smaller out-of-cavity volume compared to the commonly used transmissive collection lens group in the laser-induced fluorescence instrument. The transmittance of the ultraviolet fused quartz lens after coating with an ultraviolet transmittance film is often lower than the reflectivity of the mirror coated with an ultraviolet reflective medium film, which makes the fluorescence excitation cavity of the device have higher fluorescence collection efficiency and smaller volume.

[0056] (4) The radical generation and removal device of the application can not only realize the quantitative generation of HOx radicals, but also has the function of efficiently removing OH radicals to obtain an accurate background signal of the instrument. The combination of the two designs also has the function of peak locking of the fluorescence spectrum, which makes the application device not need to additionally increase a laser wavelength calibration device, thereby reducing the overall volume of the device.

[0057] (5) The free radical generation and removal device of the present application can produce HOx free radicals with known concentrations in a large range of concentrations, so that HOx free radicals with similar concentrations can be produced according to different actual atmospheric environments for calibration.

[0058] (6) The free radical generation and removal device of the present application has the function of automatic and rapid calibration, so that the detection sensitivity of the instrument at multiple different times within a day can be obtained.

[0059] (7) The free radical generation and removal device of the present application performs peak locking on the fluorescence spectral line, which is realized by using a photomultiplier tube in the fluorescence excitation cavity, so that the system error caused by the photomultiplier tube in the additional laser wavelength calibration device and the photomultiplier tube in the fluorescence excitation cavity can be eliminated, and the laser wavelength can be accurately locked at the optimal response wavelength of the photomultiplier tube in the fluorescence excitation cavity.

[0060] (8) Due to the long size of the light arms on both sides of the fluorescence excitation cavity of the laser-induced fluorescence instrument, the design of the upper and lower stacked fluorescence excitation double cavities can effectively reduce the lateral size of the device, and the two fluorescence excitation cavities can share one vacuum pump, but the irradiation distance of the collimated laser beam is increased, and the collimation effect of the laser beam at the lower fluorescence excitation cavity is deteriorated. The present application adopts the collimated light path design combining aspheric plano-convex lens and off-axis parabolic reflector, so that the collimation effect is greatly improved compared with the conventional spherical plano-convex lens, the stray light noise in the lower fluorescence excitation cavity is well suppressed, and the detection capability of the lower fluorescence excitation cavity is improved. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 is the overall structure schematic diagram of a high-sensitivity miniaturized HOx free radical precise measurement device provided by the embodiment of the present application.

[0062] Figure 2 is the isometric view of the free radical generation and removal device provided by the embodiment of the present application.

[0063] Figure 3 is the sectional view of the free radical generation surface of the free radical generation and removal device provided by the embodiment of the present application.

[0064] Figure 4 is the sectional view of the free radical removal surface of the free radical generation and removal device provided by the embodiment of the present application.

[0065] Figure 5 is the sectional isometric view of the mercury lamp mounting seat and the components mounted thereon provided by the embodiment of the present application.

[0066] Figure 6 is the internal top view structure schematic diagram of the fluorescence excitation cavity provided by the embodiment of the present application.

[0067] Figure 7 Figure 1 is a comparison chart of the shape and structure of the protective gas annular injection tube and the conversion gas annular injection tube provided by the embodiments of the present application.

[0068] The meanings of the reference signs are shown as follows:

[0069] 1-radical generation and removal device, 101-quartz flow tube, 102-micro stepping motor, 103-mercury lamp, 104-mercury lamp mounting seat, 105-front connecting light cylinder, 106-tilted flow outlet, 107-base, 108-photodiode, 109-photodiode mounting cylinder, 110-rear connecting light cylinder, 111-upper sealing pressing plate, 112-removal agent connecting plate, 113-precision threaded column, 114-mercury lamp light collimating lens, 115-moving grating plate, 116-telescopic spring column, 117-fixed grating plate, 118-lower sealing pressing plate, 119-focusing lens, 120-band pass filter one of 185 nm, 121-needle pressing plate, 122-capillary dispensing needle, 2-sampling nozzle, 3-protective gas annular injection tube, 4-water passing bottle group, 5-first flow meter, 6-second flow meter, 7-third flow meter, 8-fourth flow meter, 9-fifth flow meter, 10-sixth flow meter, 11-seventh flow meter, 12-industrial computer, 13-flat mirror, 14-off-axis parabolic mirror, 15-conversion gas annular injection tube, 16-fluorescence excitation cavity, 1601-photomultiplier tube, 1602-band pass filter two of 308 nm, 1603-incoming end light arm, 1604-incoming end convex cylindrical mirror, 1605-incoming end concave cylindrical mirror, 1606-fluorescence cavity main body, 1607-front concave spherical mirror, 1608-outgoing end concave cylindrical mirror, 1609-outgoing end convex cylindrical mirror, 1610-outgoing end light arm, 1611-rear concave spherical mirror, 1612-concave spherical lens, 17-laser energy meter, 18-ozone analyzer, 19-air pump, 20-eighth flow meter, 21-laser, 22-coupling lens, 23-optical fiber, 24-single-chip microcomputer, 25-laser collimating lens, 26-deceleration stepping motor, 27-double parallelogram mechanism, 28-blowing pipe, 29-temperature and humidity sensor. DETAILED DESCRIPTION

[0070] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0071] Reference is made to Figure 1A high-sensitivity miniaturized HOx radical precision measurement device comprises a radical generation and removal device 1, a light source module, a longitudinal HOx double cavity, a gas distribution module, and a collection and control system.

[0072] The radical generation and removal device 1 is used to generate HOx radicals with a known concentration or remove OH radicals in the ambient atmosphere;

[0073] The light source module is used to emit 308 nm laser light that makes OH radicals produce fluorescence and transmit into the longitudinal HOx double cavity;

[0074] The longitudinal HOx double cavity is used to excite OH radicals to produce a large amount of fluorescence and efficiently collect the fluorescence and convert it into an electrical signal;

[0075] The gas distribution module is used to inject gas into the device and maintain the gas flow state.

[0076] The collection and control system is used to monitor and control the working state of the radical generation and removal device 1 and the gas distribution module, collect the fluorescence photoelectric signal output by the longitudinal HOx double cavity, and process the data to finally obtain real-time and accurate data of the HOx radical concentration.

[0077] Referring to Figure 2 , Figure 3 , Figure 4 and Figure 5The radical generation and scavenging device 1 comprises: a quartz flow tube 101 for OH radical generation or scavenging, a micro-step motor 102 for driving a precision screw column 113 to rotate, a mercury lamp 103 for emitting ultraviolet light to photolyze oxygen and water contained in the humid synthetic air to generate HOx radicals, a mercury lamp mounting seat 104 for mounting the mercury lamp 103 and related components, a front connecting light cylinder 105 for connecting the mercury lamp mounting seat 104 and the base 107, a curved outflow port 106 for the gas flow out of the inner wall of the quartz flow tube 101, a base 107 for mounting and fixing the quartz flow tube 101 and other components, a photodiode 108 for detecting the intensity of the ultraviolet light emitted by the mercury lamp 103, a photodiode mounting cylinder 109 for mounting the photodiode 108 and related components, a rear connecting light cylinder 110 for connecting the photodiode mounting cylinder 109 and the base 107, an upper sealing press plate 111 for sealing the upper end of the gap between the quartz flow tube 101 and the base 107, a scavenger connecting plate 112 for connecting propane gas, the precision screw column 113 for adjusting the up-and-down movement of the moving grating plate 115, a mercury lamp collimating lens 114 for collimating the ultraviolet light emitted by the mercury lamp 103, the moving grating plate 115 cooperating with the fixed grating plate 117 to adjust the intensity of the mercury lamp light irradiated into the quartz flow tube 101, the extension spring column 116 making the moving grating plate 115 produce elastic restoring force, the fixed grating plate 117 cooperating with the moving grating plate 115 to adjust the intensity of the mercury lamp light irradiated into the quartz flow tube 101, a lower sealing press plate 118 for sealing the lower end of the gap between the quartz flow tube 101 and the base 107, a focusing lens 119 for focusing the collimated mercury lamp light, a band-pass filter 120 for filtering out 185 nm except for 185 nm in the mercury lamp 103 emission line, a needle head crimping plate 121 for crimping and sealing the capillary dispensing needle head 122, and the capillary dispensing needle head 122 for injecting propane into the quartz flow tube 101. In this embodiment, the mercury lamp 103 is a pen-shaped mercury lamp.

[0078] Specifically, quartz flow tube 101 is made of ultraviolet fused quartz and is mounted in the exact center of base 107. A through-hole with an inner diameter slightly larger than the outer diameter of quartz flow tube 101 is defined in the center of base 107. Sealing rings are installed at the upper and lower ends of the through-hole, sealed by upper and lower sealing plates 111 and 118, respectively. This creates a gap around the circumference of base 107 between quartz flow tube 101 and base 107. Four warp flow outlets 106 are located around the bottom of base 107, their centers flush with the bottom of quartz flow tube 101. The mercury lamp mounting base 104 is a rectangular hollow structure, with a mercury lamp 103 mounted longitudinally on the leftmost side thereof. An air hole connected to the internal space is provided below the mercury lamp 103, and a light-transmitting hole is provided in the middle of the lower luminous area near the mercury lamp 103. A mercury lamp light collimating lens 114 is installed on the right side of the light-transmitting hole, and a movable grating plate 115 and a fixed grating plate 117 are respectively installed on the right side of the mercury lamp light collimating lens 114. Both the movable grating plate 115 and the fixed grating plate 117 are provided with a horizontal light-blocking path perpendicular to the quartz flow tube 101. The width of the light-shielding area of ​​the movable grating plate 115 and the fixed grating plate 117 is equal to the width of the light-transmitting area. The lower portion of the movable grating plate 115 contacts the telescopic head of the telescopic spring column 116, while the upper portion of the movable grating plate 115 contacts the lower end of the precision threaded column 113. The upper end of the precision threaded column 113 is connected to the output shaft of the micro-stepping motor 102. The forward and reverse rotation of the micro-stepping motor 102 drives the movable grating plate 115 up and down. The front connecting light cylinder 105 is a hollow cylindrical structure that connects and secures the mercury lamp mounting base 104 to the base 107. The photodiode mounting cylinder 109 is a cylindrical hollow structure. Inside, from left to right, are mounted an 185nm bandpass filter 120, a focusing lens 119, and a photodiode 108. An air hole is provided near the photodiode 108 in the photodiode mounting cylinder 109, communicating with the interior space. The space between the mercury lamp 103 and the photodiode 108 is interconnected, with only one air hole, located on each of the mercury lamp mounting base 104 and the photodiode mounting tube 109, connecting to the outside. Four capillary dispensing needles 122 are mounted around the base 107, located above the path of the ultraviolet light emitted by the mercury lamp 103. Four micropores are located near the upper center of the quartz flow tube 101, from which the four capillary dispensing needles 122 extend, each extending approximately one-quarter the inner diameter of the quartz flow tube 101. The left side of the scavenger connecting plate 112 features a threaded connection for the propane line, and the right side features a conical hollow plunger for crimping and sealing the capillary dispensing needles 122. The needle crimping plate 121 is used to crimp and seal the capillary dispensing needles 122 to the scavenger connecting plate 112.

[0079] See also Figure 1The light source module comprises a laser 21 capable of emitting 308nm laser light for generating fluorescence of OH radicals, an optical fiber 23 for transmitting the 308nm laser light, and a coupling lens 22 for focusing and coupling the 308nm laser light into the optical fiber 23.

[0080] Referring to Figure 1 and Figure 7 The high-sensitivity longitudinal HOx double cavity comprises a sampling nozzle 2 for low-loss sampling, two fluorescence excitation cavities 16 stacked one above the other for exciting OH radicals to generate fluorescence, a laser collimating lens 25 for collimating the laser light emitted by the optical fiber 23, a plane mirror 13 and an off-axis parabolic mirror 14 for turning the collimated laser beam to be incident on the lower fluorescence excitation cavity 16 and performing secondary collimation, a laser energy meter 17 for measuring the laser energy emitted from the lower fluorescence excitation cavity 16, and a protective gas annular injection pipe 3 and a conversion gas annular injection pipe 15 for injecting protective nitrogen and nitric oxide gas into the longitudinal HOx double cavity.

[0081] Specifically, the fluorescence excitation cavities 16 are two in number and are stacked one above the other, and the two fluorescence excitation cavities 16 are symmetrically arranged left and right. The sampling nozzle 2 is installed at the top of the upper fluorescence excitation cavity 16 and is in the form of a hollow conical shape with a small hole at the top. The protective gas annular injection pipe 3 is installed at the lower part of the sampling nozzle 2. The conversion gas annular injection pipe 15 is installed between the two fluorescence excitation cavities 16. The bottom of the lower fluorescence excitation cavity 16 is connected to a vacuum pump, so that the two fluorescence excitation cavities 16 generate low pressure at the same time, and gas is injected into the two fluorescence excitation cavities 16 through the small hole at the top of the sampling nozzle 2. The laser collimating lens 25 is an aspheric plano-convex lens, which is installed at the light inlet of the upper fluorescence excitation cavity 16 and changes the divergent laser light emitted by the optical fiber 23 into a collimated laser beam. The plane mirror 13 is installed at the light outlet of the upper fluorescence excitation cavity 16, and the off-axis parabolic mirror 14 is installed at the light inlet of the lower fluorescence excitation cavity 16. The laser energy meter 17 is installed at the light outlet of the lower fluorescence excitation cavity 16. Figure 7 The upper one is the protective gas annular injection pipe 3, which is provided with a plurality of small holes at the lower part of the circumference; Figure 7 The lower one is the conversion gas annular injection pipe 15, which is provided with a plurality of small holes at the inner side of the circumference. The diameter of the conversion gas annular injection pipe 15 is greater than that of the protective gas annular injection pipe 3, and both of them adopt a double-sided injection structure.

[0082] Referring to Figure 6The single fluorescence excitation cavity 16 comprises: a fluorescence cavity body 1606 for mounting all other components in the fluorescence excitation cavity 16, a photomultiplier tube 1601 for detecting fluorescence intensity, a 308 nm band-pass filter 1602 for filtering out light other than 308 nm light, an entrance end light arm 1603 for reducing stray light when the laser beam is incident, an exit end light arm 1610 for reducing stray light when the laser beam is emitted, an entrance end convex cylindrical mirror 1604 and an exit end convex cylindrical mirror 1609 for deflecting the collimated laser beam, an entrance end concave cylindrical mirror 1605 and an exit end concave cylindrical mirror 1608 for making the laser beam reflect back and forth multiple times, a front concave spherical mirror 1607 and a rear concave spherical mirror 1611 for reflecting and focusing fluorescence, and a concave spherical lens 1612 for collimating the fluorescence reflected by the front concave spherical mirror 1607 and the rear concave spherical mirror 1611.

[0083] Specifically, the fluorescence cavity body 1606 is a square hollow structure symmetrical to the left and right. Since the two fluorescence excitation cavities 16 are symmetrically mounted to the left and right, the embodiment takes the example of the collimated laser beam being incident from the left side and emitted from the right side. Figure 6 The fluorescence cavity body 1606 is provided with the entrance end light arm 1603 and the exit end light arm 1610 on the left and right sides, respectively. The entrance end light arm 1603 and the exit end light arm 1610 are symmetrical structures. Each of the two is provided with a high-transmittance ultraviolet fused quartz window sheet on the end face outside the fluorescence cavity body 1606. Each of the two is internally provided with two tapered diaphragms, with the large opening facing inward and the small opening facing outward. The entrance end concave cylindrical mirror 1605 and the exit end concave cylindrical mirror 1608 are symmetrical structures. Each of the two is symmetrically mounted on the left and right sides inside the fluorescence cavity body 1606. Figure 6 The front concave spherical mirror 1607 is mounted on the front side (i.e., the lower side in Figure 6 The rear concave spherical mirror 1611 is mounted on the rear side (i.e., the upper side in Figure 6 The focal length of the front concave spherical mirror 1607 is slightly greater than twice the focal length of the rear concave spherical mirror 1611. The focal point of the rear concave spherical mirror 1611 is located at the center of the fluorescence cavity body 1606. The center of the rear concave spherical mirror 1611 is provided with a through hole. The front concave spherical mirror 1607, the rear concave spherical mirror 1611, the concave spherical lens 1612, the 308 nm band-pass filter 1602, and the photomultiplier tube 1601 are coaxially mounted in sequence.

[0084] Referring to Figure 1, the gas distribution module includes: a water bottle group 4 for making dry synthetic air into humid synthetic air, a first flow meter 5 for controlling the flow of humid synthetic air, a second flow meter 6 for controlling the flow of dry synthetic air, a third flow meter 7 for controlling the flow of carbon monoxide, a fourth flow meter 8 for controlling the flow of nitrogen into the radical generation and scavenging device 1, a fifth flow meter 9 for controlling the flow of nitrogen at the top, a sixth flow meter 10 for controlling the flow of propane, a seventh flow meter 11 for controlling the flow of nitric oxide, an air pump 19 for making the quartz flow tube 101 in the radical generation and scavenging device 1 produce downward flow, an eighth flow meter 20 for controlling the speed of the air pump 19, a blowing tube 28 for blowing uniform and large flow of synthetic air to the top of the radical generation and scavenging device 1, a double parallelogram mechanism 27 for controlling the standing and folding of the blowing tube 28, a reduction stepper motor 26 for controlling the movement of the double parallelogram mechanism 27, and a temperature and humidity sensor 29 for measuring the temperature and humidity of the synthetic air injected into the blowing tube 28.

[0085] Specifically, dry synthetic air is introduced into the water bottle group 4 through the first flow meter 5 to become humid synthetic air, which is mixed with dry synthetic air flowing through the second flow meter 6 to become humid synthetic air with adjustable water vapor concentration, which is mixed with carbon monoxide gas flowing through the third flow meter 7, and then injected into the blowing tube 28 through the temperature and humidity sensor 29. The first route of nitrogen is injected into the communication space between the mercury lamp 103 and the photodiode 108 through the air hole of the mercury lamp mounting seat 104 via the fourth flow meter 8. The 185nm ultraviolet light emitted by the mercury lamp 103 is used to photolyze water vapor to generate OH radicals. The path from the mercury lamp to the photodiode and the communication space are connected with the ambient air, and gases such as oxygen and nitrous oxide may exist in the path and absorb 185nm light. The absorption of these gases not only reduces the intensity of 185nm light, but also causes unstable intensity of 185nm light due to changes in the concentration of gases such as nitrous oxide that strongly absorb 185nm light in the path. Therefore, continuous injection of nitrogen, which has no absorption effect on 185nm ultraviolet light, into the communication space can eliminate other gases to eliminate this effect. The second route of nitrogen is injected into the four around the top of the sampling gas flow through the protection gas annular injection tube 3 via the fifth flow meter 9. Propane gas is injected into the quartz flow tube 101 through the sixth flow meter 10 after flowing through the capillary dispensing needle head 122 from the scavenger connecting plate 112. Nitric oxide gas is injected into the four around the middle of the sampling gas flow through the seventh flow meter 11 from the conversion gas annular injection tube 15. The air pump 19 is connected to the four air outlets 106 at the bottom of the radical generation and scavenging device 1 through the eighth flow meter 20. The flow of synthetic air injected into the blowing tube 28 is about twice the flow of the air pump 19.

[0086] Referring toFigure 1 The acquisition and control system comprises: an ozone analyzer 18 for measuring the concentration of ozone in the effluent gas at the bottom of the radical generation and removal device 1, a single-chip microcomputer 24 for controlling the rotation of all the motors in the device of the application and acquiring the signals of the temperature and humidity sensor 29 and the photodiode 108, and a work computer 12 for receiving the signals of the laser energy meter 17 and the two photomultipliers 1601 and controlling and reading the single-chip microcomputer 24.

[0087] Specifically, the work computer 12 directly receives the signals of the laser energy meter 17, the two photomultipliers 1601 and the ozone analyzer 18, indirectly receives the signals of the temperature and humidity sensor 29 and the photodiode 108 through the single-chip microcomputer 24, and indirectly controls the forward and reverse rotation of the micro stepping motor 102 and the deceleration stepping motor 26 through the single-chip microcomputer 24.

[0088] In the high-sensitivity miniaturized HOx radical precision measurement method of the application, the high-sensitivity miniaturized HOx radical precision measurement device is used, the change trend of the concentration of HOx radicals can be captured, unknown interference signals can be accurately deducted, the detection sensitivity of the upper and lower fluorescence excitation cavities at different times within a day can be quickly obtained, HOx radicals with a concentration close to the actual concentration of HOx radicals in the local environment can be output during calibration, the photomultiplier 1601 itself is used to lock the peak value of the fluorescence spectrum, and the response sensitivity and measurement precision of the laser-induced fluorescence instrument for measuring HOx radicals are improved.

[0089] (1) The process and principle of the upper fluorescence excitation cavity 16 of the device capturing OH radical fluorescence signal: The air pump 19 draws the ambient atmosphere into the quartz flow tube 101 and makes the ambient atmosphere flow downward to the sampling nozzle 2. Since the two fluorescence excitation cavities 16 are connected up and down, the vacuum pump can simultaneously draw the two fluorescence excitation cavities 16 to low pressure, and the ambient atmosphere carrying HOx radicals is sucked from the sampling nozzle 2 and injected into the two fluorescence excitation cavities 16. At the same time that the sampling gas stream is injected from the center of the protective gas annular injection tube 3 downward, nitrogen is introduced into the protective gas annular injection tube 3, and the nitrogen flows downward through the small holes in the lower part of the protective gas annular injection tube 3 to the periphery of the injected sampling gas stream, thereby forming a layer of clean protective gas to protect the cleanliness of the two fluorescence excitation cavities 16. The laser emitted by the laser 21 is focused into the light entrance head of the optical fiber 23 through the coupling lens 22, and the divergent laser emitted from the optical fiber 23 is collimated into a collimated laser beam by the collimating lens 25. The laser beam enters the upper fluorescence excitation cavity 16 from the ultraviolet fused quartz window sheet on the incident end light arm 1603 of the upper fluorescence excitation cavity 16, is deflected by the incident end convex cylindrical mirror 1604, and is reflected on the exit end concave cylindrical mirror 1608. At this time, the laser beam is reflected back and forth between the exit end concave cylindrical mirror 1608 and the incident end concave cylindrical mirror 1605, and the trajectory of the reflection will pass through the vicinity of the center of the fluorescence excitation cavity 16. The laser beam reflected multiple times excites the OH radicals in the sampling gas stream multiple times to produce strong fluorescence. The part of the fluorescence emitted upward is reflected by the rear concave spherical mirror 1611 to the front concave spherical mirror 1607 and then reflected again. The part of the fluorescence emitted downward is reflected by the front concave spherical mirror 1607 and then focused into the vicinity of the concave spherical lens 1612 from the through hole in the middle of the rear concave spherical mirror 1611. The collected fluorescence is collimated into a collimated fluorescence beam after passing through the concave spherical lens 1612. The collimated fluorescence beam is irradiated onto the photosensitive surface of the photomultiplier tube 1601 through the 308 nm band-pass filter 1602. The photomultiplier tube 1601 converts the OH radical fluorescence signal into an electrical signal. At this time, the signal output by the photomultiplier tube 1601 of the upper fluorescence excitation cavity 16 and transmitted to the industrial computer 12 is the OH radical fluorescence signal.

[0090] (2) The process and principle of the lower fluorescence excitation cavity 16 of the device capturing the OH radical fluorescence signal converted by HO2 radical: Nitric oxide is continuously introduced into the annular injection pipe 15 of the conversion gas, and the nitric oxide gas flows into the sampling gas stream through the small holes on the inner side of the annular injection pipe 15. When the HO2 radical in the sampling gas stream passes by the annular injection pipe 15, it is partially converted into OH radical by the nitric oxide. The laser beam in the upper fluorescence excitation cavity 16 is deflected after multiple reflections on the exit convex cylindrical mirror 1609. Since the entrance convex cylindrical mirror 1604 and the exit convex cylindrical mirror 1609 are convex cylindrical mirrors, they can make the laser beam diverge, while the entrance concave cylindrical mirror 1605 and the exit concave cylindrical mirror 1608 are concave cylindrical mirrors, which can make the laser beam focus. Therefore, after the collimated laser beam is reflected by the four cylindrical mirrors, the laser beam is still coaxial with the collimated laser beam incident from the ultraviolet fused quartz window sheet of the entrance optical arm 1603, and the collimated laser beam reflected by the exit convex cylindrical mirror 1609 exits from the ultraviolet fused quartz window sheet of the exit optical arm 1610. At this time, the collimated laser beam exiting from the upper fluorescence excitation cavity 16 is reflected by the plane mirror 13, and then deflected by 90 degrees downward to irradiate the off-axis parabolic mirror 14. Since the laser emitted by the optical fiber 23 is not an ideal point light source, and after collimation by the laser collimation lens 25, it is also not an ideal collimated beam, and will have a phenomenon of divergence far from the laser collimation lens 25. The off-axis parabolic mirror 14 installed on the entrance optical arm 1603 of the lower fluorescence excitation cavity 16 can perform secondary collimation and reflection of the laser beam with certain divergence into the lower fluorescence excitation cavity 16. At this time, the process of fluorescence excitation and collection in the upper fluorescence excitation cavity 16 is the same, and the photomultiplier tube 1601 of the lower fluorescence excitation cavity 16 converts the fluorescence signal of the OH radical converted by the nitric oxide into an electric signal. At this time, the signal output by the photomultiplier tube 1601 of the lower fluorescence excitation cavity 16 and transmitted to the industrial computer 12 is the fluorescence signal of the OH radical converted by the HO2 radical.

[0091] (3) The process of capturing the concentration change trend of OH radical and HO2 radical by the device, which includes the following three measurement states:

[0092] Measurement state one (HOx radical full signal measurement state): The output wavelength of the laser 21 is locked at the fluorescence excitation peak value of the OH radical, and the sixth flow meter 10 is closed to stop the injection of propane gas. During this period, the average value of the signal measured by the upper fluorescence excitation cavity 16 is: S(OH)1=S(OH) 真实 +S(OH) 干扰 +S(OH) 背景 , and the average value of the signal measured by the lower fluorescence excitation cavity 16 is: S(HO2)1=S(HO2) 真实+S(HO2) 背景 +S(OH) true + S(OH) interference, the average value of the signal measured by the laser energy meter 17 is P1, and this state is maintained for 2 min.

[0093] Measurement state two (chemical background signal measurement state): the output wavelength of the laser 21 is locked at the fluorescence excitation peak of OH radicals, the sixth flow meter 10 opens the injection of propane gas into the quartz flow tube 101, and the propane removes the OH radicals in the ambient atmosphere, during which the average value of the signal measured by the upper fluorescence excitation cavity 16 is S(OH)2=S(OH) 干扰 +S(OH) 背景 , and the average value of the signal measured by the lower fluorescence excitation cavity 16 is S(HO2)2=S(HO2) 真实 +S(HO2) 背景 +S(OH) 干扰 , the average value of the signal measured by the laser energy meter 17 is P2, and this state is maintained for 2 min.

[0094] Measurement state three (spectrum background signal measurement state): the output wavelength of the laser 21 is adjusted to be far away from the fluorescence excitation peak of OH radicals, and the sixth flow meter 10 closes the injection of propane gas, at this time, the laser does not produce fluorescence with OH radicals, during which the average value of the signal measured by the upper fluorescence excitation cavity 16 is S(OH)3=S(OH) 背景 , and the average value of the signal measured by the lower fluorescence excitation cavity 16 is S(HO2)3=S(HO2) 背景 , the average value of the signal measured by the laser energy meter 17 is P3, and this state is maintained for 1 min.

[0095] In actual measurement, the three measurement states are switched in turn within 5 min, and in the three measurement states, the single-chip microcomputer 24 controls the reduction step motor 26 to rotate to adjust the position of the moving grating plate 115 so that the intensity of the mercury lamp light detected by the photodiode 108 is zero, at this time, the mercury lamp light is completely blocked by the moving grating plate 115 and the fixed grating plate 117.

[0096] (4) The principle of the device for capturing the change trend of the concentration of OH radicals is as follows:

[0097] Firstly, in the measurement state one, the air pump 19 draws the ambient atmosphere into the quartz flow tube 101, and then the sampling nozzle 2 draws it into the upper and lower fluorescence excitation cavities 16, at this time, the signal S(OH)1 measured by the upper fluorescence excitation cavity 16 is the sum of the atmospheric OH true fluorescence signal, the OH interference signal and the background signal of the upper fluorescence excitation cavity 16, and the average value of the signal measured by the laser energy meter 17 is P1.

[0098] Then, in the second measurement state, propane is pumped into the quartz flow tube 101 to remove OH radicals, at this time the signal S(OH)2 detected by the upper fluorescence excitation chamber 16 is the sum of the OH interference signal and the background signal of the upper fluorescence excitation chamber 16, and the average value of the signal measured by the laser energy meter 17 during this period is P2.

[0099] Finally, in the third measurement state, laser and OH radicals do not intersect to produce fluorescence, at this time the signal S(OH)3 detected by the upper fluorescence excitation chamber 16 is the background signal of the upper fluorescence excitation chamber 16, and the average value of the signal measured by the laser energy meter 17 during this period is P3.

[0100] The change trend of S(OH)2 is the change trend of the OH interference signal, which can be used for analysis of the interference source. The change trend of S(OH)2 is the change trend of the OH interference signal, which can be used for analysis of the interference source.

[0101] (5) The principle of the device for capturing the change trend of HO2 radical concentration is as follows:

[0102] First, in the first measurement state, the environment is pumped into the quartz flow tube 101 by the air pump 19, and then is pumped into the upper and lower fluorescence excitation chambers 16 by the sampling nozzle 2. The atmospheric HO2 radical is partially converted into OH radical between the upper and lower fluorescence excitation chambers 16, at this time the signal S(HO2)1 detected by the lower fluorescence excitation chamber 16 is the sum of the fluorescence signal of the atmospheric HO2 converted into OH, the background signal of the lower fluorescence excitation chamber 16, the real fluorescence signal of the atmospheric OH, and the OH interference signal, and the average value of the signal measured by the laser energy meter 17 during this period is P1.

[0103] Then, in the second measurement state, propane is pumped into the quartz flow tube 101 to remove OH radicals, at this time the signal S(HO2)2 detected by the lower fluorescence excitation chamber 16 is the sum of the atmospheric HO2 converted into OH, the background signal of the lower fluorescence excitation chamber 16, and the OH interference signal, and the average value of the signal measured by the laser energy meter 17 during this period is P2. 2转化的 OH's fluorescence signal, the background signal of the lower fluorescence excitation chamber 16, and the OH interference signal, and the average value of the signal measured by the laser energy meter 17 during this period is P2.

[0104] Finally, in the third measurement state, laser and OH radicals do not intersect to produce fluorescence, at this time the signal S(HO2)3 detected by the lower fluorescence excitation chamber 16 is the background signal of the lower fluorescence excitation chamber 16, and the average value of the signal measured by the laser energy meter 17 during this period is P3.

[0105] The change trend of S(HO2)2 is the change trend of the atmospheric HO2 radical real concentration, wherein k is the ratio of the detection sensitivity of the upper and lower fluorescence excitation chambers 16.

[0106] ​​(6) The process and principle of the device for quickly obtaining the detection sensitivity of the upper and lower fluorescence excitation cavities at different times within a day: close the propane gas injected into the quartz flow tube 15, and control the fourth flow meter 8 to continuously inject a small amount of nitrogen gas into the connecting space between the mercury lamp 103 and the photodiode 108, so as to eliminate the influence of the absorption of ultraviolet light emitted by the mercury lamp by other gases. The single-chip microcomputer 24 controls the forward rotation of the reduction stepper motor 26, and the double parallelogram mechanism 27 drives the air blowing pipe 28 to rise to a position with an angle of 45 degrees with the quartz flow tube 101, and the air outlet direction of the air blowing pipe 28 is directed to the center of the top of the quartz flow tube 101. Then, the first flow meter 5 and the second flow meter 6 are opened, and the synthetic air becomes humidified synthetic air with adjustable water vapor concentration after passing through the first flow meter 5, the water bottle group 4, and the second flow meter 6. The humidified synthetic air passes through the temperature and humidity sensor 29 and is injected into the air blowing pipe 28, at which time the water vapor concentration in the synthetic air measured by the temperature and humidity meter is [H2O]. About half of the flow of the humidified synthetic air blown out by the air blowing pipe 28 is sucked into the quartz flow tube 101, and the single-chip microcomputer 24 controls the rotation of the reduction stepper motor 26. At this time, the ultraviolet light emitted by the mercury lamp 103 passes through the mercury lamp collimating lens 114, the moving grating plate 115, and the fixed grating plate 117 in turn and is irradiated into the downward flowing humidified synthetic air in the quartz flow tube 101, so that the humidified synthetic air is photolyzed, and the concentrations of the generated OH free radicals and HO2 free radicals are [OH] and [HO2], respectively, and [OH] = [HO2]. Then, the mercury lamp light passes backward through the 185 nm band-pass filter 120 and the focusing lens 119 in turn and is irradiated onto the photosensitive surface of the photodiode 108. At this time, the output voltage of the photodiode 108 received by the single-chip microcomputer 24 is V, the ozone concentration measured by the ozone analyzer 18 is [O3], and the output electrical signal of the photomultiplier tube 1601 of the upper fluorescence excitation cavity 16 is S' OH , and the signal of the laser energy meter 17 is P'.

[0107] Then, according to formula (1), the sensitivity C OH of the upper fluorescence excitation cavity 16 for measuring OH free radicals is calculated as follows:

[0108]

[0109] wherein, and are the oxygen absorption cross section and the water vapor absorption cross section, respectively, which are fixed values obtained from literature. [O2] is the concentration of oxygen in the synthetic air in the quartz flow tube 101, which is a fixed value provided by the gas supplier. k1 is the proportion of the energy of the laser in the upper fluorescence excitation cavity 16 to the energy of the laser irradiated onto the laser energy meter 17, which is a fixed value determined in advance in the laboratory.

[0110] Subsequently, the seventh flow meter 11 is closed, and the electric signal outputted from the photomultiplier tube 1601 in the lower fluorescence excitation chamber 16 is S' HO2 Then, the seventh flow meter 11 is opened, and the seventh flow meter 11 controls the injection of the nitric oxide gas into the upper portion of the lower fluorescence excitation chamber 16 through the conversion gas annular injection pipe 15, at this time, part of the HO2 is converted into OH free radical, and the electric signal outputted from the photomultiplier tube 1601 in the lower fluorescence excitation chamber 16 is S HO2,NO Finally, the third flow meter 7 controls the injection of the carbon monoxide gas into the blowing pipe 28 together with the humidified synthetic air, the carbon monoxide gas is absorbed by the quartz flow pipe 101 to convert the OH free radical into HO2 free radical completely, and the seventh flow meter 11 keeps the injection of the nitric oxide gas, at this time, the electric signal outputted from the photomultiplier tube 1601 in the lower fluorescence excitation chamber 16 is S HO2,NO+CO .

[0111] Then, according to the formula (2), the sensitivity C of the lower fluorescence excitation chamber 16 for measuring the HO2 free radical is calculated as follows: HO2

[0112]

[0113] Wherein, p is the conversion ratio of the HO2 free radical into OH free radical by the inputted nitric oxide from the conversion gas annular injection pipe 15, and k2 is the ratio of the laser energy in the lower fluorescence excitation chamber 16 to the laser energy irradiated onto the laser energy meter 17, which is a constant value measured in the laboratory in advance. Since the whole calibration process is completed within ten minutes, the signals measured by the laser energy meter 17 and the ozone analyzer 18 are still P' and [O3] respectively.

[0114] Since the output voltage of the photodiode 108 is linearly related to the ozone concentration [O3] measured by the ozone analyzer 18, the formula (1) and the formula (2) can be rewritten as the following formula (3) and formula (4) respectively:

[0115]

[0116] Wherein, k3 is the ratio of the output voltage V of the photodiode 108 to the ozone concentration [O3] measured by the ozone analyzer 18, which is a constant value measured in the laboratory in advance. In the actual field observation, the photodiode 108 can be used instead of the ozone analyzer 18, so as to further reduce the volume of the whole device.

[0117] ​Since the whole process of acquiring the detection sensitivity of the upper and lower fluorescence excitation cavities 16 is realized by automatic control, the acquisition of single detection sensitivity is completed within 10 minutes, which is much more efficient than manual operation. Therefore, the detection sensitivity at different times within a day can be acquired, and the real-time HOx free radical concentration can be obtained by dividing the real-time measured fluorescence signal by the product of the proximally calibrated detection sensitivity and the laser energy.

[0118] (7) The principle of the device of the present application outputting HOx free radicals similar to the actual HOx free radical concentration in the local environment: closing the propane gas injected into the quartz flow tube 15, and moving the light blocking path of the movable grating plate 115 and the fixed grating plate 117 can make the mercury lamp light (ultraviolet light) passing through uniform in the direction perpendicular to the quartz flow tube 101. The single-chip microcomputer 24 controls the rotation of the reduction stepper motor 26, the stepper motor 26 drives the precision threaded column 113 to rotate, the precision threaded column 113 pushes the movable grating plate 115 to move up and down, and the mutual movement between the movable grating plate 115 and the fixed grating plate 117 will cause the intensity of the mercury lamp light irradiating into the quartz flow tube 101 to change, and the concentration of OH free radicals and HO2 free radicals will also change. Therefore, the HOx free radicals similar to the actual HOx free radical concentration in the local environment can be adjusted according to the intensity of the fluorescence signal.

[0119] (8) The principle of the device of the present application using the photoelectric multiplier tube 1601 itself to accurately lock the peak value of the fluorescence spectrum: the single-chip microcomputer 24 controls the reduction stepper motor 26 to reverse, the double parallelogram mechanism 27 drives the air blowing pipe 28 to retract, the humidified synthetic air and carbon monoxide gas injected into the air blowing pipe 28 are closed, and the propane gas injected into the quartz flow tube 15 is closed. The single-chip microcomputer 24 controls the rotation of the reduction stepper motor 26 to adjust the position of the movable grating plate 115 so that the intensity of the mercury lamp light (ultraviolet light intensity) detected by the photodiode 108 reaches the highest. At this time, the mercury lamp light will photolyze the water vapor in the environment atmosphere, thereby generating high concentration of OH free radicals. Then, the laser 21 starts to slowly adjust the wavelength of the output laser within a certain range, at this time, the fluorescence signal detected by the photoelectric multiplier tube 1601 in the upper fluorescence excitation cavity 16 also changes, and when the scanning is completed, the wavelength of the laser 21 is positioned at the position with the highest fluorescence signal.

[0120] The conventional peak locking method is to use an additional laser wavelength calibration device, which uses a high-temperature filament to generate high concentration of OH free radicals, changes the wavelength of the laser to obtain the fluorescence signal, and accurately locks the peak value of the OH free radical fluorescence spectrum.

[0121] Since the application adopts the photomultiplier 1601 of the fluorescence excitation cavity 16 itself for locking the fluorescence spectrum line, compared with the conventional way of additionally equipping a laser wavelength calibration device, the application does not have the problem of deviation between the response peak values of the photomultiplier in the laser wavelength calibration device and the photomultiplier in the low-pressure fluorescence detection cavity, and the fluorescence excitation cavity has the characteristic of high detection sensitivity, which makes the laser wavelength be able to be positioned at the position of the best sensitivity of the instrument, and the process of locking the fluorescence spectrum line peak value can be performed every one hour.

[0122] The above is only the preferred embodiment of the application, and is not used to limit the application, and any modification, equivalent replacement and improvement within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A highly sensitive and miniaturized HOx free radical precision measurement device, characterized in that: The device includes: Free radical generation and scavenging device (1), light source module, longitudinal HOx double cavity, gas distribution module, collection and control system; The free radical generation and scavenging device (1) is used to generate HOx free radicals or scavenger OH free radicals, and is installed at the top of the longitudinal HOx double chamber; The light source module is used to emit laser light that causes OH free radicals to generate fluorescence and transmit the laser light into the longitudinal HOx dual cavity; The longitudinal HOx dual cavity is used for laser excitation of OH free radicals to generate fluorescence, and the fluorescence is collected and converted into an electrical signal; The gas distribution module is used for injecting gas into the device and maintaining the flow state of the gas flow; The acquisition and control system is used to monitor and control the working states of the free radical generation and scavenging device (1) and the gas distribution module, and simultaneously acquires and processes the fluorescence photoelectric signals output by the longitudinal HOx dual cavities.

2. A highly sensitive and miniaturized HOx free radical precise measurement device according to claim 1, characterized in that: The free radical generation and scavenging device (1) comprises: a quartz flow tube (101) for generating or scavenging OH free radicals, a base (107) for mounting and fixing the quartz flow tube (101) and related components, a mercury lamp (103) for emitting ultraviolet light to photolyze oxygen and water contained in moist synthetic air to generate HOx free radicals, a mercury lamp mounting base (104) for mounting the mercury lamp (103) and related components, a front connecting light cylinder (105) for connecting the mercury lamp mounting base (104) and the base (107), a photodiode (108) for detecting the intensity of ultraviolet light, a photodiode mounting cylinder (109) for mounting the photodiode (108) and related components, and a rear connecting light cylinder (110) for connecting the photodiode mounting cylinder (109) and the base (107); A mercury lamp (103), a mercury lamp collimating lens (114), a movable grating plate (115), and a fixed grating plate (117) are sequentially arranged in the front connecting light cylinder (105) along the propagation direction of the ultraviolet light; wherein the movable grating plate (115) cooperates with the fixed grating plate (117) to adjust the light intensity of the mercury lamp irradiated into the quartz flow tube (101); The rear connecting light cylinder (110) is provided with a bandpass filter (120), a focusing lens (119), and a photodiode (108) in sequence along the propagation direction of the ultraviolet light; The quartz flow tube (101) is used for injecting humidified synthetic air; a through hole is provided around a position above the ultraviolet light path in the quartz flow tube (101) for a capillary dispensing needle (122) to extend into the quartz flow tube (101); the capillary dispensing needle (122) is used for injecting propane gas into the quartz flow tube (101); and a warp flow outlet (106) for outflow of air is provided at the bottom of the quartz flow tube (101).

3. A highly sensitive and miniaturized HOx free radical precise measurement device according to claim 1 or 2, characterized in that: The longitudinal HOx dual cavity comprises: two fluorescence excitation cavities (16) superimposed and installed in an upper and lower manner for exciting OH free radicals to generate fluorescence, a sampling nozzle (2) for sampling gas in the free radical generation and scavenging device (1) into the upper fluorescence excitation cavity (16), a laser collimating lens (25) for collimating the laser emitted by the light source module, a plane reflector (13) and an off-axis parabolic reflector (14) for redirecting the collimated laser beam to be incident on the lower fluorescence excitation cavity (16) and performing secondary collimation, a laser energy meter (17) for measuring the energy of the laser emitted from the lower fluorescence excitation cavity (16), and a protective gas annular injection pipe (3) and a conversion gas annular injection pipe (15) for respectively injecting nitrogen and nitric oxide into the longitudinal HOx dual cavity; The upper and lower fluorescence excitation cavities (16) are symmetrically installed; a protective gas annular injection pipe (3) is installed at the lower part of the sampling nozzle (2); a conversion gas annular injection pipe (15) is installed between the upper and lower fluorescence excitation cavities (16); a plurality of small holes are opened at the lower part of the circumference of the protective gas annular injection pipe (3); a plurality of small holes are opened on the inner side of the circumference of the conversion gas annular injection pipe (15); the diameter of the conversion gas annular injection pipe (15) is larger than the diameter of the protective gas annular injection pipe (3); the bottom of the lower fluorescence excitation cavity (16) is connected to a vacuum pump; a laser collimating lens (25) is installed at the light inlet of the upper fluorescence excitation cavity (16); a plane reflector (13) is installed at the light outlet of the upper fluorescence excitation cavity (16); an off-axis parabolic reflector (14) is installed at the light inlet of the lower fluorescence excitation cavity (16); and a laser energy meter (17) is installed at the light outlet of the lower fluorescence excitation cavity (16).

4. A highly sensitive and miniaturized HOx free radical precise measurement device according to claim 3, characterized in that: A single fluorescence excitation cavity (16) comprises: a fluorescence cavity body (1606), a photomultiplier tube (1601) for detecting fluorescence intensity, a second bandpass filter (1602), an incident end optical arm (1603) for reducing stray light of a laser beam when incident, an exit end optical arm (1610) for reducing stray light of a laser beam when exiting, an incident end convex cylindrical reflector (1604) and an exit end convex cylindrical reflector (1609) for deflecting a collimated laser beam, an incident end concave cylindrical reflector (1605) and an exit end concave cylindrical reflector (1608) for causing the laser beam to reflect back and forth multiple times, a front concave spherical reflector (1607) and a rear concave spherical reflector (1611) for reflecting and focusing fluorescence, and a concave spherical lens (1612) for collimating the fluorescence reflected by the front concave spherical reflector (1607) and the rear concave spherical reflector (1611). The fluorescent cavity body (1606) is a square hollow structure with bilateral symmetry. An incident light arm (1603) and an output light arm (1610) are respectively provided on the left and right sides. The incident light arm (1603) and the output light arm (1610) are symmetrical structures. A quartz window is provided on the end surface of the fluorescent cavity body (1606). Two conical apertures are installed inside the two apertures, with the large opening facing inward and the small opening facing outward. The incident end concave cylindrical reflector (1605) and the exit end concave cylindrical reflector (1608) have the same structure and size, and are symmetrically mounted on the left and right sides of the interior of the fluorescent cavity body (1606). The front concave spherical reflector (1607) and the rear concave spherical reflector (1611) are respectively installed on the front and rear sides of the fluorescent cavity body (1606); the focal length of the front concave spherical reflector (1607) is greater than twice the focal length of the rear concave spherical reflector (1611); the focus of the rear concave spherical reflector (1611) is located at the center of the fluorescent cavity body (1606); and a through hole is opened at the center of the rear concave spherical reflector (1611); the front concave spherical reflector (1607), the rear concave spherical reflector (1611), the concave spherical lens (1612), the second bandpass filter (1602) and the photomultiplier tube (1601) are coaxially installed in sequence.

5. A highly sensitive and miniaturized HOx free radical precise measurement device according to claim 4, characterized in that: The gas distribution module provides the following gases to the device; The dry synthetic air is passed through the first flow meter (5) into the water bottle group (4) to become moist synthetic air. The moist synthetic air is mixed with the dry synthetic air flowing through the second flow meter (6) to become moist synthetic air with adjustable water vapor concentration. The moist synthetic air is mixed with the carbon monoxide gas flowing out of the third flow meter (7) and then flows through the temperature and humidity sensor (29) and is injected into the blowing pipe (28). The blowing pipe (28) is used to blow the moist synthetic air to the quartz flow tube (101) in the free radical generation and scavenging device (1). The temperature and humidity sensor (29) is used to measure the temperature and humidity of the synthetic air injected into the blowing pipe (28). The first nitrogen gas is injected into the communication space between the mercury lamp (103) and the photodiode (108) through the fourth flow meter (8); The second nitrogen gas is injected into the surrounding area of ​​the top of the sampling air flow from the protective gas annular injection pipe (3) through the No. 5 flow meter (9); Propane gas is injected into the quartz flow tube (101) through the No. 6 flow meter (10); Nitrogen monoxide is injected into the surroundings of the middle of the sampling air flow from the conversion gas annular injection pipe (15) through the No. 7 flow meter (11); The air pump (19) is connected to the warp flow outlet (106) at the bottom of the quartz flow tube (101) through the No. 8 flow meter (20), so that the quartz flow tube (101) generates a downward air flow.

6. A highly sensitive and miniaturized HOx free radical precise measurement device according to claim 5, characterized in that: The acquisition and control system comprises: an ozone analyzer (18) for measuring the ozone concentration in the gas flowing out from the bottom of the quartz flow tube (101); a single-chip microcomputer (24) for controlling all electrical components in the device to simultaneously acquire signals from a temperature and humidity sensor (29) and a photodiode (108); and an industrial control computer (12) for receiving signals from a laser energy meter (17) and photomultiplier tubes (1601) in two fluorescence excitation cavities (16) and controlling and reading the single-chip microcomputer (24).

7. A highly sensitive and miniaturized HOx free radical precise measurement device according to claim 1, characterized in that: The light source module comprises: a laser (21) for emitting laser light that causes OH free radicals to generate fluorescence, an optical fiber (23) for transmitting the laser light, and a coupling lens (22) for focusing and coupling the laser light into the optical fiber (23).

8. A highly sensitive and miniaturized method for accurately measuring HOx free radicals, characterized in that: The method for capturing the trend of HOx radical concentration changes in the highly sensitive, miniaturized, and precise HOx radical measurement device described in claim 5 is as follows: Set three measurement states: Measurement state 1: The output wavelength of the laser (21) is locked at the peak of the fluorescence excitation of the OH free radical, and the No. 6 flow meter (10) turns off the injection of propane gas. During this period, the average value of the signal measured by the upper fluorescence excitation cavity (16) is S(OH)1, the average value of the signal measured by the lower fluorescence excitation cavity (16) is S(HO2)1, and the average value of the signal measured by the laser energy meter (17) is P1. This state is maintained for t1 time; Measurement state 2: The output wavelength of the laser (21) is locked at the peak of the fluorescence excitation of the OH free radical, and the No. 6 flow meter (10) starts to inject propane gas into the quartz flow tube (101). The propane removes the OH free radicals in the ambient atmosphere. During this period, the average value of the signal measured by the upper fluorescence excitation cavity (16) is S(OH)2, the average value of the signal measured by the lower fluorescence excitation cavity (16) is S(HO2)2, and the average value of the signal measured by the laser energy meter (17) is P2. This state is maintained for t2 time; Measurement state three: the output wavelength of the laser (21) is adjusted to be away from the fluorescence excitation peak of the OH free radical, and the injection of propane gas is turned off by the No. 6 flow meter (10). At this time, the laser and the OH free radical intersect and no fluorescence is generated. During this period, the average value of the signal measured by the upper fluorescence excitation cavity (16) is S(OH)3, the average value of the signal measured by the lower fluorescence excitation cavity (16) is S(HO2)3, and the average value of the signal measured by the laser energy meter (17) is P3. This state is maintained for t3 time; In actual measurement, the three measurement states are switched cyclically in sequence. In these three measurement states, the position of the movable grating plate (115) is adjusted so that the intensity of the ultraviolet light detected by the photodiode (108) is zero, that is, the ultraviolet light emitted by the mercury lamp (103) is completely blocked by the movable grating plate (115) and the fixed grating plate (117); The method to capture the trend of OH radical concentration is: First, in measurement state 1, the ambient atmosphere is drawn into the quartz flow tube (101), and then drawn into the upper and lower fluorescence excitation chambers (16) by the sampling nozzle (2). At this time, the signal S(OH)1 measured by the upper fluorescence excitation chamber (16) is the sum of the atmospheric OH true fluorescence signal, the OH interference signal, and the background signal of the upper fluorescence excitation chamber (16). During this period, the average value of the signal measured by the laser energy meter (17) is P1; Then, in the second measurement state, propane is pumped into the quartz flow tube (101) to remove OH radicals. At this time, the signal S(OH)2 measured by the upper fluorescence excitation cavity (16) is the sum of the OH interference signal and the background signal of the upper fluorescence excitation cavity (16). During this period, the average value of the signal measured by the laser energy meter (17) is P2; Finally, in the measurement state three, the laser and the OH radical intersect and no fluorescence is generated. At this time, the signal S(OH)3 measured by the upper fluorescence excitation cavity (16) is the background signal of the upper fluorescence excitation cavity (16). During this period, the average value of the signal measured by the laser energy meter (17) is P3. The changing trend of is the changing trend of the real concentration of atmospheric OH radicals; The changing trend of is the changing trend of OH interference signal; The method to capture the trend of HO2 radical concentration is: First, in the measurement state 1, the ambient air is drawn into the quartz flow tube (101), and then drawn into the upper and lower fluorescence excitation chambers (16) by the sampling nozzle 2. The atmospheric HO2 free radicals are partially converted into OH free radicals by NO between the upper and lower fluorescence excitation chambers (16). At this time, the signal S(HO2)1 measured by the lower fluorescence excitation chamber (16) is the sum of the fluorescence signal of the atmospheric HO2 converted into OH, the background signal of the lower fluorescence excitation chamber (16), the true fluorescence signal of the atmospheric OH, and the OH interference signal. During this period, the average value of the signal measured by the laser energy meter (17) is P1; Then, in the second measurement state, propane is drawn into the quartz flow tube (101) to remove the OH radicals. At this time, the signal S(HO2)2 measured by the lower fluorescence excitation cavity (16) is the atmospheric HO 2转化的 The sum of the fluorescence signal of OH, the background signal of the lower fluorescence excitation chamber (16) and the interference signal of OH, during which the average value of the signal measured by the laser energy meter (17) is P2; Finally, in the measurement state three, the laser and the OH radical intersect and no fluorescence is generated. At this time, the signal S(HO2)3 measured by the lower fluorescence excitation cavity (16) is the background signal of the lower fluorescence excitation cavity (16). During this period, the average value of the signal measured by the laser energy meter (17) is P3. The changing trend of is the changing trend of the real concentration of atmospheric HO2 free radicals; wherein, k is the ratio of the detection sensitivities of the upper and lower fluorescence excitation cavities (16).

9. A highly sensitive and miniaturized method for accurately measuring HOx free radicals, characterized in that: A highly sensitive and miniaturized HOx free radical precision measurement device according to claim 5 is used to peak-lock the fluorescence spectrum using the photomultiplier tube (1601) itself, specifically in the following manner: The humidified synthetic air and carbon monoxide gas injected into the blowing tube (28) are closed, and the propane gas injected into the quartz flow tube (15) is closed; The position of the movable grating plate (115) is adjusted so that the intensity of the ultraviolet light emitted by the mercury lamp (103) detected by the photodiode (108) reaches the highest level, at which time the ultraviolet light will photolyze water vapor in the ambient atmosphere, thereby generating OH free radicals; Then, the light source module begins to adjust the wavelength of the emitted laser within a certain range. At this time, the fluorescence signal detected by the photomultiplier tube (1601) of the upper fluorescence excitation cavity (16) also changes accordingly. When the scan is completed, the wavelength of the laser emitted by the light source module is positioned to the position where the fluorescence signal is the highest.

10. A computer program product, characterized in that It includes a computer program / instruction, which, when executed by a processor, implements the highly sensitive miniaturized HOx free radical precise measurement method according to claim 8 or 9.

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