A method and device for generating a hydroxyl radical OH-hydroperoxyl radical HO2-organic peroxyl radical RO2 multi-radical standard source and application thereof

Abstract

The application belongs to the technical field of environmental monitoring, and discloses a OH-HO2-RO2 multi-radical standard source generation method and device and application thereof, wherein different water vapor content wet air is controlled to enter a flow tube and receive 184.9nm ultraviolet irradiation to generate synchronous photolysis, and based on the real-time measured water vapor content, ultraviolet radiation intensity value and the absorption cross-section value of oxygen and water vapor at 184.9nm, the OH and HO2 concentrations generated in the flow tube are inversed; carbon monoxide or different kinds of volatile organic compounds are controlled to be added into the flow tube to react with OH radicals to generate stable concentrations of HO2 or RO2. 6 10 3 The method and device can generate specific concentrations of OH, HO2 and different kinds of RO2 on line, and the concentration of generated radicals can be adjusted according to requirements, the concentration range is 10​​

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environmental monitoring, and particularly relates to a method and device for generating an OH-HO2-RO2 multi-radical standard source and application thereof. BACKGROUND

[0002] Atmospheric oxidation represented by OH, HO2 and RO2 radicals determines the residence time and influence range of primary pollutants (such as methane, carbon monoxide, volatile organic compounds and nitrogen monoxide) in the atmosphere, and drives the generation and conversion of secondary pollutants (such as ozone and secondary organic aerosols), and is a key factor in atmospheric environmental chemistry research. Atmospheric radicals have strong activity (with a lifetime of usually milliseconds to seconds) and low concentration (with an average concentration of OH radicals in the global atmosphere of about 10 6 ~10 7 molecules / cm 3 ), and accurate in-situ measurement of typical atmospheric radicals (such as OH, HO2 and RO2) is a key technical problem in the field of atmospheric environmental science. Gas expansion laser-induced fluorescence technology is the most widely used technology for atmospheric radical measurement, but the relationship between the resonance fluorescence signal of laser-induced radicals and the concentration of radicals needs to be determined by standard gas calibration, that is, the sensitivity of the gas expansion laser-induced fluorescence atmospheric radical measurement system is determined by using OH, HO2 and RO2 radicals with specific concentrations, and then the concentrations of OH, HO2 and RO2 radicals in the environment air are calculated.

[0003] Atmospheric radicals have strong activity, and no standard gas can be selected, so standard gas can only be generated by an online generation method. At present, the online generation method of atmospheric radicals mainly includes laser photolysis of ozone, ozone-alkene steady-state generation and ultraviolet photolysis. The laser photolysis of ozone is to generate singlet oxygen atoms (O 1 D) by photolysis of ozone by a 248nm laser, and the singlet oxygen atoms (O 1D reacts with water vapor (H2O) to produce OH radicals; the ozone-olefin steady-state generation method is based on the gas-phase reaction of ozone with olefins (such as isoprene, alpha-pinene, etc.), and the concentration of generated OH radicals is indirectly deduced by measuring the consumption rate of reactants or the generation rate of products; the ultraviolet photolysis method is to generate OH and HO2 radicals by irradiating water vapor with a low-pressure mercury lamp, and the concentrations of generated OH and HO2 radicals are quantified by measuring the concentrations of H2O and O3 and the absorption cross-sections of H2O and O2. At present, these three methods can only generate OH and HO2 radicals and can only be applied in the laboratory, and are not suitable for field applications, and there are also problems such as large volume of generation device, high operation cost, inconvenient operation and complex calculation process. Therefore, it is an urgent technical problem to develop a universal standard source generation method and device for OH-HO2-RO2 multi-radical generation and widely applicable to environmental atmospheric radical measurement systems in different application scenarios, which is particularly important for realizing online measurement of atmospheric multi-radicals. SUMMARY

[0004] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide an OH-HO2-RO2 multi-radical standard source generation method and device and its application.

[0005] The technical scheme adopted by the present application to solve its technical problems is:

[0006] An OH-HO2-RO2 multi-radical standard source generation method, comprising the following steps:

[0007] (1) Dry air, wet air and volatile organic compounds (VOCs) or carbon monoxide (CO) are introduced into the flow tube by mass flow controllers, and the water vapor content value of the gas entering the flow tube is monitored in real time by a high-precision dew point instrument L;

[0008] (2) The flow tube is fixed in the ultraviolet photolysis cavity, and the gas in the flow tube is irradiated by 184.9 nm ultraviolet light, in which O2 and H2O are simultaneously photolyzed to produce ozone, OH and HO2 radicals; when CO is introduced, CO reacts with OH radicals to convert all of them into HO2 radicals; when volatile organic compounds are introduced, volatile organic compounds react with OH radicals to generate all specific types of RO2 radicals;

[0009] (3) The intensity of 184.9 nm ultraviolet radiation is detected in real time, and the ozone concentration at the center of the flow tube is measured by an ozone analyzer, a function relationship between the ozone concentration at the center of the flow tube and the ultraviolet radiation intensity is established, and the concentrations of generated OH, HO2 and RO2 are calculated by combining the water vapor concentration data measured by the high-precision dew point instrument L and the absorption cross-section values of O2 and H2O at 184.9 nm.

[0010] The OH-HO2-RO2 multi-radical standard source generating device for realizing the method as described above comprises a UV light source mounting cavity, a UV light source, a UV light source adjusting cavity, a UV light source absorbing cavity, a UV photolysis cavity, a flow pipe, a gas distribution unit, a standard source control unit and a photocell, the UV light source is closely mounted on the UV light source mounting cavity, the UV light source mounting cavity, the UV light source adjusting cavity, the UV light source absorbing cavity, the UV photolysis cavity and the standard source control unit are closely connected in sequence along the horizontal direction, the UV light source can generate UV light, the UV light can pass through the UV light source adjusting cavity, the UV light source absorbing cavity, the UV photolysis cavity and the standard source control unit in sequence and be detected by the photocell therein, the UV light source adjusting cavity can perform collimation, focusing and energy adjustment operations on the UV light generated by the UV light source, the UV light source absorbing cavity can absorb the conditioned UV light and then weaken the UV light radiation intensity quantitatively, the UV photolysis cavity can perform synchronous photolysis on the gas in the flow pipe to generate O3, OH, HO2 and different types of RO2, the gas distribution unit can accurately control the gas flow and switch different gas supplies for the flow pipe, the UV photolysis cavity and the UV light source absorbing cavity, the standard source control unit can provide a human-computer interaction interface and communicate with and control the gas distribution unit, the UV light source and the photocell, and the photocell can monitor the UV light source radiation intensity in real time and output the result to the standard source control unit for display and storage.

[0011] Further, the UV light source is closely connected with the UV light source mounting cavity through a UV light source fixing member, the UV light source mounting cavity is an aluminum shell with an open end and a hollow interior, the UV light source comprises a lamp tube, the lamp tube of the UV light source is arranged in the hollow interior of the aluminum shell, and a UV photolysis cavity purge gas outlet is connected to the aluminum shell; the UV light source is directly inserted into the UV light source mounting cavity and is sealed and fixed through the UV light source fixing member.

[0012] Alternatively, the UV light source can continuously and stably emit 184.9 nm ultraviolet rays.

[0013] Further, the UV light source adjusting cavity comprises an aluminum flange type shell with open ends and a hollow interior, a lens mounting member, a diaphragm, a filter and a plano-convex lens, the aluminum flange type shell is closely connected with one side of the open end of the UV light source mounting cavity, the diaphragm, the filter and the plano-convex lens are connected in sequence along the horizontal direction in the hollow interior of the aluminum flange type shell through the lens mounting member.

[0014] Further, the ultraviolet light source absorption cavity comprises an aluminum cylindrical shell with open ends and a hollow interior, a planar window mirror, and a nitrous oxide inlet and outlet, the aluminum cylindrical shell is in close coaxial communication with the aluminum flange-shaped shell of the ultraviolet light source adjusting cavity, the planar window mirror is arranged in the hollow interior of the aluminum cylindrical shell and is coaxially and symmetrically arranged in the horizontal direction, the nitrous oxide inlet and outlet is arranged on the aluminum cylindrical shell between the two planar window mirrors, and the nitrous oxide inlet and outlet is connected with the gas distribution unit through a pipeline;

[0015] Further, the ultraviolet light source absorption cavity comprises an aluminum cylindrical shell with open ends and a hollow interior, a planar window mirror, and a nitrous oxide inlet and outlet, the aluminum cylindrical shell is in close coaxial communication with the aluminum flange-shaped shell of the ultraviolet light source adjusting cavity, the planar window mirror is arranged in the hollow interior of the aluminum cylindrical shell and is coaxially and symmetrically arranged in the horizontal direction, the nitrous oxide inlet and outlet is arranged on the aluminum cylindrical shell between the two planar window mirrors, and the nitrous oxide inlet and outlet is connected with the gas distribution unit through a pipeline;

[0016] Further, the ultraviolet light source absorption cavity comprises an aluminum cylindrical shell with open ends and a hollow interior, a planar window mirror, and a nitrous oxide inlet and outlet, the aluminum cylindrical shell is in close coaxial communication with the aluminum flange-shaped shell of the ultraviolet light source adjusting cavity, the planar window mirror is arranged in the hollow interior of the aluminum cylindrical shell and is coaxially and symmetrically arranged in the horizontal direction, the nitrous oxide inlet and outlet is arranged on the aluminum cylindrical shell between the two planar window mirrors, and the nitrous oxide inlet and outlet is connected with the gas distribution unit through a pipeline;

[0017] The reaction gas channel is arranged in the vertical direction, i.e. the Y-axis direction, and comprises a reaction gas input channel and a reaction gas output channel arranged in coaxial communication. The reaction gas output channel is arranged below the aluminum cubic shell, and the reaction gas input channel is arranged at the upper part of the aluminum cubic shell. The flow tube can penetrate through the aluminum cubic shell and is fixed by the flow tube fixing ring. The bottom of the flow tube penetrates through the orthogonal region of the ultraviolet light channel and the reaction gas channel and extends into the reaction gas output channel, and is fixed in the aluminum cubic shell by the flow tube fixing base. The flow tube receives the reaction gas input by the gas distribution unit, and the photolysis reaction occurs at the orthogonal region of the ultraviolet light channel and the reaction gas channel to generate free radicals of a specific concentration. The gas expansion laser-induced fluorescence atmospheric free radical measurement system is arranged in close connection with the aluminum cubic shell through the standard source connection flange. Two standard source connection flange purge gas inlets are arranged on the standard source connection flange and connected with the gas distribution unit. The gas distribution unit can introduce purge gas as sheath gas into the reaction gas output channel through the standard source connection flange purge gas inlet, reduce the loss efficiency of the generated free radicals on the wall surface of the standard source connection flange, and ensure that the generated free radicals of a specific concentration can enter the gas expansion laser-induced fluorescence atmospheric free radical measurement system without loss, thereby ensuring the accuracy of calibration;

[0018] The purging / emptying air channel includes a purging gas channel and an emptying air hole, which are respectively arranged at one end of the aluminum square shell in the vertical direction, i.e., the Z-axis direction. The ultraviolet photolysis cavity purging gas inlet is arranged at the proximal end in the vertical direction and is in communication with the ultraviolet light outlet channel. The ultraviolet photolysis cavity purging gas inlet is connected to the gas distribution unit. The gas distribution unit can guide the purging gas into the ultraviolet light outlet channel through the ultraviolet photolysis cavity purging gas inlet and then pass through the gap between the flow tube and the ultraviolet photolysis cavity, the ultraviolet light inlet channel, the ultraviolet light source absorption cavity, the ultraviolet light source adjustment cavity, and finally pass through the ultraviolet light source installation cavity and flow out through the ultraviolet photolysis cavity purging gas outlet. The flow tube emptying port is arranged at the proximal end in the vertical direction and is in communication with the reaction gas output channel. The flow tube emptying port can empty the excess reaction gas in the flow tube and ensure the pressure balance in the flow tube.

[0019] Further, the gas distribution unit includes solenoid valves, mass flow controllers, a bubbler Q, a gas mixer, a high-precision dew point instrument, and cylinder gases. By switching the solenoid valves and setting the mass flow controller flow rate, the synthetic air, CO, or VOCs of different humidity can be controlled to enter the flow tube, or the purging gas can be controlled to enter the ultraviolet photolysis cavity, or the nitrous oxide gas G3 of different concentrations can be controlled to enter the ultraviolet light source absorption cavity.

[0020] Further, the gas distribution unit includes solenoid valves, mass flow controllers, a bubbler, a gas mixer, a high-precision dew point instrument, and cylinder gases. The gas mixer, high-precision dew point instrument, and flow tube are sequentially connected. The cylinder gases include synthetic air, high-purity nitrogen, nitrous oxide gas, carbon monoxide, and volatile organic compounds. The gas mixer includes a first gas mixer and a second gas mixer. The synthetic air is connected to the flow tube through the solenoid valves, mass flow controllers, first gas mixer, high-precision dew point instrument, and flow tube.

[0021] The high-purity nitrogen and nitrous oxide gas are connected to the ultraviolet light source absorption cavity through the solenoid valves, mass flow controllers, and second gas mixer. The high-purity nitrogen is also connected to the flow tube through the solenoid valves, mass flow controllers, first gas mixer, high-precision dew point instrument, and flow tube. The high-purity nitrogen is also connected to the ultraviolet photolysis cavity through the solenoid valves and mass flow controllers.

[0022] The carbon monoxide and volatile organic compounds are connected to the flow tube through the solenoid valves, mass flow controllers, first gas mixer, high-precision dew point instrument, and flow tube.

[0023] Further, the solenoid valves include a three-way solenoid valve, a first two-way solenoid valve, a second two-way solenoid valve, a third two-way solenoid valve, a fourth two-way solenoid valve, a fifth two-way solenoid valve, a sixth two-way solenoid valve, and a seventh two-way solenoid valve.

[0024] The mass flow controller comprises a first mass flow controller, a second mass flow controller, a third mass flow controller, a fourth mass flow controller, a fifth mass flow controller, a sixth mass flow controller, and a seventh mass flow controller. The bubbler is connected to the first gas mixer through the second mass flow controller, and is also connected to a three-way electromagnetic valve. The first mass flow controller, the second mass flow controller, and the third mass flow controller are all connected to the first gas mixer.

[0025] The synthetic air is sequentially connected to the three-way electromagnetic valve, the first mass flow controller, the first gas mixer, a high-precision dew point instrument, and a flow tube.

[0026] The synthetic air is also sequentially connected to the three-way electromagnetic valve, the first two-way electromagnetic valve, the third mass flow controller, and the first gas mixer.

[0027] The high-purity nitrogen is respectively connected to the three-way electromagnetic valve, the fourth two-way electromagnetic valve, the fifth two-way electromagnetic valve, and the sixth two-way electromagnetic valve. The fourth two-way electromagnetic valve is connected to a standard source connection flange purge gas inlet through the fourth mass flow controller. The fifth two-way electromagnetic valve is connected to an ultraviolet light source purge gas inlet through the fifth mass flow controller. The sixth two-way electromagnetic valve is connected to the second gas mixer through the sixth mass flow controller.

[0028] The nitrous oxide gas is sequentially connected to the seventh two-way electromagnetic valve, the seventh mass flow controller, and the second gas mixer. The second gas mixer is connected to a nitrous oxide inlet and outlet.

[0029] The carbon monoxide is sequentially connected to the second two-way electromagnetic valve, the third mass flow controller, and the first gas mixer.

[0030] The volatile organic matter is sequentially connected to the third two-way electromagnetic valve, the third mass flow controller, and the first gas mixer.

[0031] Further, the synthetic air is 79% N2 and 21% O2, and the gas purity is 99.9999%. The gas purity of the high-purity nitrogen is 99.9999%. The nitrous oxide gas is 500 ppm nitrous oxide gas, and the balance gas is 99.9999% high-purity N2. The carbon monoxide is 10% carbon monoxide, and the balance gas is 99.9999% high-purity N2. The volatile organic matter is 10 ppm volatile organic matter, such as ethylene, propane, and isoprene, and the balance gas is 99.9999% high-purity N2. The above percentages are all volume percentages.

[0032] The synthetic air passes through a three-way electromagnetic valve and then passes through a first mass flow controller and a bubbler respectively, the first mass flow controller controls the flow of the synthetic air, and the bubbler is used for humidifying the synthetic air and precisely controlling the flow of the humidified synthetic air through a second mass flow controller, the two air flows are connected together through a first gas mixer, and after being fully mixed, the air flows through a high-precision dew point instrument and then enters the flow tube. By adjusting the flow of the dry air flow controller and the wet air flow controller, the water vapor content of the synthetic air entering the flow tube can be precisely controlled, and the high-precision dew point instrument can measure the water vapor content in real time. Preferably, the bubbler is a bottle-shaped structure made of polytetrafluoroethylene, and 2 / 3 of the capacity of the bottle is filled with ultrapure water. The gas inlet and outlet are arranged on the bottle cap, the gas inlet is directly connected to the bottom of the bottle to ensure that the synthetic air enters the bottle in the form of bubbles, and the gas outlet is arranged on the bottle cap to prevent the ultrapure water from overflowing and damaging the wet air mass flow controller.

[0033] Further, the standard source control unit is provided with a microcomputer all-in-one machine, an ultraviolet light source power supply and a photocell 28, wherein the microcomputer all-in-one machine is electrically connected with the gas distribution unit, the photocell and the ultraviolet light source power supply, and the ultraviolet light source power supply is connected with the ultraviolet light source through a waterproof aviation plug.

[0034] The device as described above is applied in OH, HO2 and RO2 multi-radical generation.

[0035] The device as described above is applied in online measurement of environmental atmospheric radicals.

[0036] The application has the following advantages and positive effects:

[0037] 1. The OH-HO2-RO2 multi-radical standard source generation method and device can generate hydroxyl radicals (OH), hydrogen peroxide radicals (HO2) and organic peroxide radicals (RO2) with specific concentrations online, and can automatically adjust the concentrations of the generated OH, HO2 and various types of RO2 radicals according to needs, and the concentration range is 10 6 ~10 10 molecules / cm 3 , which can meet the calibration and calibration requirements of the atmospheric radical online measurement device. In the application, wet air with different water vapor contents is controlled to enter the flow tube, oxygen and water vapor in the flow tube are synchronously photolyzed under ultraviolet irradiation, and based on the real-time monitored water vapor content, ultraviolet radiation intensity value and absorption cross-section value of oxygen and water vapor at 184.9nm, the generated OH and HO2 radical concentrations in the flow tube can be calculated; by controlling the addition of carbon monoxide or different types of volatile organic compounds into the flow tube, stable concentrations of HO2 or RO2 radicals can be generated by reacting with OH radicals.

[0038] 2、The device of the application has the structure of ultraviolet photolysis cavity coupled with ultraviolet light source conditioning, filtering, energy adjustment, light condensation, purging, detection and the like, which ensures the stability and controllability of 184.9nm ultraviolet light source in synchronously photolyzing H2O and O2, and has the advantages of high accuracy and good consistency of OH, HO2 and RO2 free radical concentration.

[0039] 3、The application can automatically adjust the gas distribution through the gas distribution unit, thereby controlling the generation of OH free radicals, HO2 free radicals and different types of RO2 free radicals with a certain concentration, and has the advantages of convenient and fast use and high automation degree.

[0040] 4、The standard source control unit integrated in the device can control and manage the entire standard source system, has the advantages of compact structure and convenient human-computer interaction, and the whole device can operate independently and can meet the application of laboratory / field calibration and the like.

[0041] 5、The OH-HO2-RO2 multi-free radical standard source generation method and device of the application can monitor the parameters of gas humidity, temperature, oxygen content, flow tube center ozone concentration and 184.9nm ultraviolet radiation intensity in real time, and has the advantages of high reliability and good comparability based on the OH, HO2 and RO2 free radical concentrations inversed based on real-time measurement results.

[0042] 6、The device of the application can generate specific concentrations of hydroxyl free radicals (OH), hydroperoxyl free radicals (HO2) and various organic peroxyl free radicals (RO2) on line, and is suitable for calibrating and calibrating the OH, HO2 and RO2 measurement system. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is a structural connection diagram of the device of the application.

[0044] The drawing mark: ultraviolet light source installation cavity 1, ultraviolet light source 2, ultraviolet light source fixing part 3, ultraviolet photolysis cavity purging gas outlet 4, ultraviolet light source adjustment cavity 5, lens installation rotating part 6, diaphragm 7, filter 8, plano-convex lens 9, ultraviolet light source absorption cavity 10, plane window mirror 11, nitrous oxide inlet and outlet 12, ultraviolet photolysis cavity 13, flow tube fixed ring 14, flow tube fixed base 15, movable light window 16, ultraviolet photolysis cavity purging gas inlet 17, flow tube emptying port 18, flow tube protection sleeve 19, flow tube 20, quartz sand core 21, flow tube connecting pipe cap 22, gas distribution inlet 23, gas distribution unit 24, standard source control unit 25, microcomputer all-in-one machine 26, ultraviolet light source power supply 27, phototube 28, standard source connecting flange 29, standard source connecting flange purging gas inlet 30, gas expansion laser-induced fluorescence atmospheric free radical measurement system 31. DETAILED DESCRIPTION

[0045] The application is further described below in connection with examples, which are illustrative and not limiting, and cannot be used to limit the protection scope of the application.

[0046] The various experimental operations involved in the embodiments are conventional techniques in the art, and the parts not specifically noted herein can be implemented by referring to various commonly used tool books, scientific and technical literature or related instructions, manuals, etc. before the application date of the present application. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application. If not specifically indicated, the technical means used in the examples are conventional means known to those skilled in the art, and the raw materials used are commercially available.

[0047] A method and device for generating an OH-HO2-RO2 multi-radical standard source, by configuring high-purity humid air, receiving 184.9 nm ultraviolet light source irradiation to photolyze and generate equal amounts of OH and HO2 radicals, the reaction process is as follows:

[0048]

[0049]

[0050]

[0051]

[0052] The OH and HO2 concentrations generated in the photolysis zone can be calculated by the photolysis reaction rate equation, and the calculation formula is as follows:

[0053]

[0054] wherein is the absorption cross section of water, is the photodissociation quantum yield of water, F is the actinic flux, and t is the photolysis time.

[0055] The actinic flux F and the photolysis time t are difficult to accurately determine, and can be obtained by measuring the ozone concentration in the photolysis zone:

[0056]

[0057]

[0058] By calibrating the oxygen absorption cross section and the water vapor absorption cross section value, combined with the actual measurement results of the water vapor and oxygen content of the humid air and the ozone concentration at the center position of the photolysis zone, the concentrations of the generated OH radicals and HO2 radicals can be calculated, and the calculation formula is as follows:

[0059]

[0060] By adding carbon monoxide gas to high-purity humid air, the OH radicals generated by photolysis oxidize CO and are entirely converted into HO2 radicals. At this point, the concentration of HO2 radicals is twice the concentration of OH radicals. The specific reaction is as follows:

[0061]

[0062]

[0063] By adding volatile organic compounds (VOCs) to high-purity humid air, the OH radicals generated by photolysis oxidize the VOCs and completely generate the corresponding RO2 radicals. At this point, the concentration of RO2 is equal to the concentration of OH radicals. The specific reaction is as follows, where RH represents an alkane. These represent unsaturated hydrocarbons that undergo H-transfer or addition reactions with OH radicals to generate peroxy organic radicals RO2.

[0064]

[0065]

[0066] After the system stabilizes, the ozone concentration is positively correlated with the 184.9nm ultraviolet radiation intensity. By accurately monitoring the moisture content of the humid air and the ultraviolet radiation intensity, combined with the absorption cross-sections of O2 and H2O at 184.9nm, the concentrations of various free radicals such as OH, HO2, and RO2 can be accurately calculated. By adjusting the moisture content of the humid air through the gas distribution unit, the concentration range of the generated free radicals can be dynamically adjusted within 10. 6 ~10 10 molecules / cm 3 And generate different kinds of RO2 free radicals.

[0067] A method for generating a standard source of OH-HO2-RO2 multi-radicals includes the following steps:

[0068] (1) Three sets of high-precision mass flow controllers control dry air, humid air and volatile organic compounds or carbon monoxide to enter the flow tube 20 respectively, and the water vapor content of the gas entering the flow tube 20 is monitored in real time by a high-precision dew point meter L.

[0069] (2) The flow tube 20 is fixed in the ultraviolet photolysis chamber 13. The gas in the flow tube 20 is irradiated with 184.9nm ultraviolet light. O2 and H2O undergo synchronous photolysis to produce ozone, OH and HO2 free radicals respectively. When CO is introduced, CO reacts with OH free radicals and is completely converted into HO2 free radicals. When a specific type of volatile organic compound (such as ethylene, isoprene, methane, propane, etc.) is introduced, the volatile organic compound reacts with OH free radicals to generate a specific type of RO2 free radical.

[0070] (3) Real-time detection of 184.9nm ultraviolet radiation intensity and measurement of ozone concentration data at the center of flow tube 20 by high-precision ozone analyzer (chemiluminescence method) to establish the functional relationship between ozone concentration at the center of flow tube 20 and ultraviolet radiation intensity. Combined with high-precision dew point meter L to obtain inlet water gas concentration data, the concentrations of OH, HO2 and RO2 can be calculated.

[0071] An OH-HO2-RO2 multi-radical standard source generator to realize the above method, such as... Figure 1 As shown, the device includes an ultraviolet light source mounting cavity 1, an ultraviolet light source 2, an ultraviolet light source adjustment cavity 5, an ultraviolet light source absorption cavity 10, an ultraviolet photolysis cavity 13, a flow tube 20, a gas distribution unit 24, a standard source control unit 25, and a phototube 28. The ultraviolet light source mounting cavity 1, ultraviolet light source adjustment cavity 5, ultraviolet light source absorption cavity 10, ultraviolet photolysis cavity 13, and standard source control unit 25 are sequentially and tightly connected in a horizontal direction, wherein the ultraviolet light source mounting cavity 1, ultraviolet light source adjustment cavity 5, ultraviolet light source absorption cavity 10, and ultraviolet photolysis cavity 13 are coaxially arranged. The ultraviolet light source 2 is tightly mounted on the ultraviolet light source mounting cavity 1. The ultraviolet light source 2 can stably radiate ultraviolet light at 184.9 nm. The ultraviolet light generated by the ultraviolet light source 2 can sequentially pass through the ultraviolet light source adjustment cavity 5, ultraviolet light source absorption cavity 10, ultraviolet photolysis cavity 13, and standard source control unit 25 and be detected by the phototube 28 within them. The gas distribution unit 24 is connected to the flow tube 20, the ultraviolet photolysis chamber 13, and the ultraviolet light source absorption chamber 10 through pipelines and accurately distributes gas; the phototube 28 is fixed in the standard source control unit 25 and is coaxially arranged with the ultraviolet photolysis chamber 13.

[0072] The ultraviolet light source adjustment cavity 5 can collimate, focus, and adjust the energy of the ultraviolet light generated by the ultraviolet light source 2. The ultraviolet light source absorption cavity 10 can absorb the conditioned ultraviolet light and quantitatively reduce the intensity of ultraviolet light radiation. The gas distribution unit 24 can precisely control the gas flow rate and switch the supply of different gases for the flow tube 20, the ultraviolet photolysis cavity 13, and the ultraviolet light source absorption cavity 10. The ultraviolet photolysis cavity 13 can synchronously photolyze the gas in the flow tube 20 to produce O3, OH, HO2, and different types of RO2. The standard source control unit 25 can provide a human-machine interface to automatically control the gas distribution unit 24, the ultraviolet light source 2, and the phototube 28. The phototube 28 can monitor the ultraviolet light source radiation intensity in real time and output the results to the standard source control unit for display and storage.

[0073] In use, the ultraviolet light source 2 can stably radiate ultraviolet light of 184.9 nm. After conditioning by the ultraviolet light source conditioning cavity 5, the light source has a good shape and stable radiation intensity, ensuring the stable generation of O3, OH, HO2 and different types of RO2 in the flow tube 20 in the ultraviolet photolysis cavity 13. The ultraviolet light source absorption cavity 10 is arranged between the ultraviolet light source conditioning cavity 5 and the ultraviolet photolysis cavity 13. Different concentrations of nitrous oxide gas G3 are controlled to enter by the gas distribution unit 24. Nitrous oxide absorbs ultraviolet radiation of 184.9 nm, which can dynamically adjust the ultraviolet radiation intensity of 184.9 nm in the flow tube 20 in the ultraviolet photolysis cavity 13, ensuring the stability of the water molecule and oxygen absorption cross section in the flow tube 20, which can effectively improve the accuracy of the OH, HO2 and different types of RO2 concentration calculated based on the absorption cross section inversion. The standard source control unit 25 communicates and controls the gas distribution unit 24, the ultraviolet light source 2 and the phototube 28, respectively, to obtain the oxygen and water content of the gas entering the flow tube and the ultraviolet radiation intensity of 184.9 nm in the flow tube 20 in the ultraviolet photolysis cavity 13 in real time, and then automatically calculate the OH, HO2 and different types of RO2 concentration, which has the advantage of traceable generation concentration. The whole device can run independently and can meet the calibration or calibration of the atmospheric radical measurement system in the laboratory / field environment.

[0074] In the embodiment, the ultraviolet light source 2 is arranged in close connection with the ultraviolet light source mounting cavity 1 through the ultraviolet light source fixing member 3. The ultraviolet light source mounting cavity 1 is an aluminum shell with an open end and a hollow interior (not labeled in the figure). The ultraviolet light source 2 includes a lamp tube (not labeled in the figure). The lamp tube of the ultraviolet light source 2 is arranged in the hollow interior of the aluminum shell. The ultraviolet photolysis cavity purge gas outlet 4 is arranged on the aluminum shell. The ultraviolet light source 2 is directly inserted into the ultraviolet light source mounting cavity 1 and is sealed and fixed by the ultraviolet light source fixing member 3. Preferably, the ultraviolet light source 2 is arranged in a vertical direction. The insertion depth of the ultraviolet light source 2 is that the center of the light-emitting area of the ultraviolet light source 2 is arranged on the center axis of the ultraviolet light source mounting cavity 1, where the ultraviolet radiation intensity is the highest.

[0075] Preferably, the inner and outer surfaces of the aluminum shell are blackened to reduce the influence of scattered light. Alternatively, a circular hole (not labeled in the figure) is formed in the upper part of the aluminum shell. The circular hole is arranged in cooperation with the ultraviolet light source 2. The ultraviolet light source 2 can be movably and detachably inserted into the circular hole. For example, an O-ring groove and a screw hole (both not shown in the figure) are formed on the surface of the circular hole. The ultraviolet light source fixing member 3 is sealed and fixed on the ultraviolet light source mounting cavity 1 together with the ultraviolet light source 2.

[0076] Preferably, the ultraviolet light source fixing member 3 is set as an aluminum flange type cylinder, and an O-ring groove (not shown in the figure) is arranged inside the cylinder. The ultraviolet light source 2 can be inserted into the cylinder and sealed by the O-ring (not shown in the figure) for heat dissipation. Preferably, a black fluorine O-ring is arranged in the O-ring groove to avoid the aging problem of the O-ring caused by light leakage or ultraviolet radiation.

[0077] Preferably, the hollow interior of the ultraviolet light source mounting cavity 1 is set as a cylinder with a diameter of 60 mm. Alternatively, a 1 / 4NPT threaded hole (not shown in the figure) is formed in the center of the outer surface of the aluminum shell, and a 1 / 4NPT external thread rotating stainless steel sleeve joint is installed as the ultraviolet photolysis cavity purge gas outlet 4 to guide the purge gas in the cavity.

[0078] In the embodiment, the ultraviolet light source 2 can continuously and stably emit 184.9 nm ultraviolet light. For example, the ultraviolet light source 2 is a commercial low-pressure mercury lamp light source, such as a BHK 81-1025-01 type ozone ultraviolet lamp tube, which can continuously and stably emit 184.9 nm ultraviolet light. The ultraviolet light source has a pen-shaped outline, with a light-emitting area at the upper end, an outer diameter of 9 mm, and a length of 50.8 mm. The lower end is an electrode area, which is an aluminum shell capable of efficient heat conduction.

[0079] In the embodiment, the ultraviolet light source adjusting cavity 5 includes an aluminum flange type shell (not labeled in the figure) with open ends and a hollow interior, a lens mounting rotating member 6, an aperture 7, a filter 8, and a plano-convex lens 9. The aluminum flange type shell is closely connected and communicated with one side of the open end of the ultraviolet light source mounting cavity 1. The aperture 7, the filter 8, and the plano-convex lens 9 are sequentially connected and arranged in the hollow interior of the aluminum flange type shell along the horizontal direction through the lens mounting rotating member 6.

[0080] The ultraviolet light source absorbing cavity 10 includes an aluminum cylindrical shell (not labeled in the figure) with open ends and a hollow interior, a plane window mirror 11, and a nitrous oxide inlet and outlet 12. The aluminum cylindrical shell is closely coaxially connected and communicated with the aluminum flange type shell of the ultraviolet light source adjusting cavity 5. The plane window mirror 11 is arranged in the hollow interior of the aluminum cylindrical shell and is coaxially and symmetrically arranged in two along the horizontal direction. The nitrous oxide inlet and outlet 12 is connected and arranged on the aluminum cylindrical shell between the two plane window mirrors 11, and is closely connected and arranged with the gas distribution unit 24.

[0081] The ultraviolet photolysis cavity 13 is set as an aluminum cubic shell (not labeled in the figure), and holes (not labeled in the figure) are arranged on the six faces thereof, respectively serving as ultraviolet light channels, reaction gas channels, and purge / evacuation gas channels. The ultraviolet light channels and the reaction gas channels are vertically orthogonal, and the purge / evacuation gas channels are arranged in the third direction. Preferably, the inner and outer surfaces thereof are black oxidized to reduce the influence of scattered light.

[0082] The ultraviolet light channel is arranged along the horizontal direction (i.e. the X-axis direction), and includes an ultraviolet light incident channel 33 and an ultraviolet light exit channel 34 coaxially connected and communicated, the ultraviolet light incident channel 33 is coaxially and closely communicated with the ultraviolet light source absorption cavity 10, the ultraviolet light exit channel 34 is coaxially arranged with the phototube 28, and the movable light window 16 is movably connected on the ultraviolet light incident channel 33, and the movable light window 16 can open and close the ultraviolet light incident channel 33;

[0083] The reaction gas channel is arranged along the vertical direction (i.e. the Y-axis direction), and includes a reaction gas input channel 35 and a reaction gas output channel 36 coaxially connected and communicated, the reaction gas output channel 36 is arranged below the aluminum square shell, and the reaction gas input channel 35 is arranged at the upper part of the aluminum square shell, the flow tube 20 can penetrate through and be fixed by the flow tube fixing ring 14, the bottom of the flow tube 20 penetrates through the orthogonal region of the ultraviolet light channel and the reaction gas channel and is arranged and extended in the reaction gas output channel 36, and is fixed in the aluminum square shell by the flow tube fixing base 15. The flow tube 20 receives the reaction gas input by the gas distribution unit 24, and the photolysis reaction occurs at the orthogonal region of the ultraviolet light channel and the reaction gas channel, to generate free radicals of a specific concentration. The gas expansion laser-induced fluorescence atmospheric free radical measurement system 31 is closely connected with the aluminum square shell through the standard source connecting flange 29, two standard source connecting flange purge gas inlets 30 are oppositely arranged on the standard source connecting flange 29 and connected with the gas distribution unit 24, the gas distribution unit 24 can introduce purge gas into the reaction gas output channel 36 as sheath gas through the standard source connecting flange purge gas inlets 30, to reduce the loss efficiency of the generated free radicals on the wall surface of the standard source connecting flange 29, and to ensure that the generated free radicals of a specific concentration can be losslessly introduced into the gas expansion laser-induced fluorescence atmospheric free radical measurement system 31, so as to ensure the calibration accuracy;

[0084] The purging / evacuation air channel includes a purging gas channel and an evacuation air hole (both not labeled in the figure), which are arranged at one end of the aluminum cube shell in the vertical direction (i.e. Z-axis direction). The ultraviolet photolysis cavity purging gas inlet 17 is arranged at the proximal end in the vertical direction and is in communication with the ultraviolet light outlet channel 34. The ultraviolet photolysis cavity purging gas inlet 17 is connected to the gas distribution unit 24. The gas distribution unit 24 can guide the purging gas to enter the ultraviolet light outlet channel 34 through the ultraviolet photolysis cavity purging gas inlet 17 and then pass through the gap between the flow tube 20 and the ultraviolet photolysis cavity 13, the ultraviolet light inlet channel 33, the ultraviolet light source absorption cavity 10, the ultraviolet light source adjustment cavity 5, and finally flow out through the ultraviolet photolysis cavity purging gas outlet 4 on the ultraviolet light source mounting cavity 1. The flow tube evacuation port 18 is arranged at the proximal end in the vertical direction and is in communication with the reaction gas output channel 36. The flow tube evacuation port 18 can evacuate excess reaction gas in the flow tube 20 to ensure pressure balance in the flow tube 20.

[0085] Preferably, the interior of the ultraviolet light source adjustment cavity 5 is provided with an SM1 standard thread, which can be screwed into the lens mounting turnpiece 6. The two ends are coaxially fixed together through screws and the ultraviolet light source mounting cavity 1 and the ultraviolet light source absorption cavity 10 and are sealed by O-rings. The lens mounting seat turnpiece is cylindrical, has an SM1 external thread on the outside, can be directly screwed into the ultraviolet light source adjustment cavity 5 and freely adjusted in position, has an SM1 internal thread on the inside, and sequentially mounts the adjustable diaphragm 7, the optical filter 8, and the plano-convex lens 9. A plurality of small holes with a diameter of 1 mm are provided between the external thread and the internal thread as the ultraviolet photolysis cavity purging gas channel for carrying out ozone generated by scattered light radiation in the ultraviolet light source mounting cavity and the ultraviolet light adjustment cavity 5. Preferably, the adjustable diaphragm 7 is adjusted to a diameter of 10 mm, which can effectively reduce the influence of ultraviolet light source scattered light. The optical filter 8 can cut off 254 nm ultraviolet light emitted by the ultraviolet light source, avoiding 254 nm light photolysis of ozone, and further causing free radical quantitative interference. The plano-convex lens 9 can be uncoated, ensuring that the transmittance of 184.9 nm ultraviolet light is more than 90%, and can focus the ultraviolet light source to ensure that the ultraviolet light passes vertically through the flow tube.

[0086] The ultraviolet light source adjusting cavity 5 is a flange sleeve type aluminum cylinder, and the two ends are respectively sealed and connected together with the ultraviolet light source mounting cavity 1 and the ultraviolet light source absorbing cavity 10 through screws and O-rings. Preferably, the inner and outer surfaces are blackened to reduce the influence of scattered light. The inner wall of the ultraviolet light source adjusting cavity 5 is provided with an SM1 internal thread, and the lens mounting rotating part 6 can be screwed into the ultraviolet light source adjusting cavity 5 for installation and fixed by an SM1 compression ring. The lens mounting rotating part 6 is a threaded cylinder provided with an SM1 thread inside and outside, and six through holes with a diameter of 1.5 mm are uniformly distributed between the internal and external threads as channels for ultraviolet light source cavity purging gas. From close to the ultraviolet light source, a diaphragm 7, a filter 8 and a plano-convex lens 9 are arranged in turn to realize the adjustment of the ultraviolet light source, including collimation, filtering and focusing of 184.9 nm ultraviolet light. Preferably, the diaphragm 7 is a general type, one end is an SM1 internal thread, the other end is an SM1 external thread, the internal thread end is directly screwed into the lens mounting rotating part 6 for fixation, and the aperture can be freely adjusted between 1-12 mm; the filter 8 is a narrow band pass filter that only allows 184.9 nm ± 5 nm wavelength ultraviolet light to pass and is fixed in the lens mounting rotating part 6 by an SM1 compression ring; the plano-convex lens 9 is an ultraviolet fused quartz uncoated type with a diameter of 25.4 mm and a focal length of 30 mm, and the plane is light-incident. It is fixed in the lens mounting rotating part 6 by an SM1 compression ring. Preferably, the distance between the plane of the plano-convex lens 9 and the center of the ultraviolet light source is 25 mm, which can realize the collimation of the ultraviolet light source.

[0087] In the embodiment, the gas distribution unit includes solenoid valves, mass flow controllers, a bubbler Q, a gas mixer, a high-precision dew point instrument L, and steel cylinder gases. The gas mixer, the high-precision dew point instrument L, and the flow tube 20 are sequentially connected. The steel cylinder gases include synthetic air G1, high-purity nitrogen gas G2, nitrous oxide gas G3, carbon monoxide G4, and volatile organic compounds G5. The gas mixer includes a first gas mixer H1 and a second gas mixer H2. The synthetic air G1 is connected to the flow tube 20 through solenoid valves, mass flow controllers, the first gas mixer H1, the high-precision dew point instrument L, and the flow tube 20. The synthetic air G1 is also connected to the ultraviolet photolysis cavity 13 through solenoid valves.

[0088] The high-purity nitrogen gas G2 and the nitrous oxide gas G3 are connected to the ultraviolet light source absorbing cavity 10 through solenoid valves, mass flow controllers, the second gas mixer H2, and the ultraviolet light source absorbing cavity 10. The high-purity nitrogen gas G2 is also connected to the flow tube 20 through solenoid valves, mass flow controllers, the first gas mixer H1, the high-precision dew point instrument L, and the flow tube 20.

[0089] The carbon monoxide G4 and the volatile organic compounds G5 are connected to the flow tube 20 through solenoid valves, mass flow controllers, the first gas mixer H1, the high-precision dew point instrument L, and the flow tube 20.

[0090] Preferably, the electromagnetic valves include a three-way electromagnetic valve V1, a first two-way electromagnetic valve V2, a second two-way electromagnetic valve V3, a third two-way electromagnetic valve V4, a fourth two-way electromagnetic valve V5, a fifth two-way electromagnetic valve V6, a sixth two-way electromagnetic valve V7, and a seventh two-way electromagnetic valve V8.

[0091] The mass flow controllers include a first mass flow controller Z1, a second mass flow controller Z2, a third mass flow controller Z3, a fourth mass flow controller Z4, a fifth mass flow controller Z5, a sixth mass flow controller Z6, and a seventh mass flow controller Z7. The bubbler Q is connected to the first gas mixer H1 through the second mass flow controller Z2 and is also connected to the three-way electromagnetic valve V1. The first mass flow controller Z1, the second mass flow controller Z2, and the third mass flow controller Z3 are all connected to the first gas mixer H1.

[0092] The synthetic air G1 is sequentially connected to the three-way electromagnetic valve V1, the first mass flow controller Z1, the first gas mixer H1, a high-precision dew point instrument L, and a flow tube 20.

[0093] The synthetic air G1 is also sequentially connected to the three-way electromagnetic valve V1, the first two-way electromagnetic valve V2, the third mass flow controller Z3, and the first gas mixer H1.

[0094] The high-purity nitrogen gas G2 is connected to the three-way electromagnetic valve V1, the fourth two-way electromagnetic valve V5, the fifth two-way electromagnetic valve V6, and the sixth two-way electromagnetic valve V7. The fourth two-way electromagnetic valve V5 is connected to a standard source connection flange purge gas inlet 30 through the fourth mass flow controller Z4. The fifth two-way electromagnetic valve V6 is connected to an ultraviolet photolysis cavity purge gas inlet 17 through the fifth mass flow controller Z5. The sixth two-way electromagnetic valve V7 is connected to the second gas mixer H2 through the sixth mass flow controller Z6.

[0095] The nitrous oxide gas G3 is sequentially connected to the seventh two-way electromagnetic valve V8, the seventh mass flow controller Z7, and the second gas mixer H2. The second gas mixer H2 is connected to a nitrous oxide inlet and outlet 12.

[0096] The carbon monoxide G4 is sequentially connected to the second two-way electromagnetic valve V3, the third mass flow controller Z3, and the first gas mixer H1.

[0097] The volatile organic matter G5 is sequentially connected to the third two-way electromagnetic valve V4, the third mass flow controller Z3, and the first gas mixer H1.

[0098] More preferably, the synthetic air G1 is 79% N2, 21% O2, with a gas purity of 99.9999%; the high-purity nitrogen gas G2 has a gas purity of 99.9999%; the nitrous oxide gas G3 is 500 ppm nitrous oxide gas, with the balance being 99.9999% high-purity N2; the carbon monoxide G4 is 10% carbon monoxide, with the balance being 99.9999% high-purity N2; the volatile organic G5 is 10 ppm volatile organic, such as ethylene, propane, isoprene, etc., with the balance being 99.9999% high-purity N2. The percentages above are all volume percentages.

[0099] The synthetic air G1 passes through the three-way electromagnetic valve V1 and then through the first mass flow controller Z1 and the bubbler Q. The first mass flow controller Z1 controls the flow rate of the synthetic air G1, and the bubbler Q is used to humidify the synthetic air G1 and precisely control the flow rate of the humidified synthetic air G1 through the second mass flow controller Z2. The two gas streams are connected together through the first gas mixer H1, mixed thoroughly, pass through the high-precision dew point instrument L, and then enter the flow tube 20. By adjusting the flow rate of the dry air flow controller and the wet air flow controller, the water vapor content of the synthetic air G1 entering the flow tube 20 can be precisely controlled, and the high-precision dew point instrument L can measure the water vapor content in real time. More preferably, the bubbler Q is a bottle-shaped structure made of polytetrafluoroethylene, with 2 / 3 of the volume filled with ultrapure water. The bottle cap is provided with an air inlet and an air outlet. The air inlet is directly connected to the bottom of the bottle to ensure that the synthetic air G1 entering the bottle forms bubbles. The air outlet is provided on the bottle cap to prevent the ultrapure water from spilling and damaging the wet air mass flow controller (not shown in the figure).

[0100] The synthetic air G1 is connected with the first two-way electromagnetic valve V2 after passing through the three-way electromagnetic valve V1, and whether the synthetic air G1 is introduced into the third mass flow controller Z3 can be controlled; the reaction gas CO or the volatile organic G5 is connected with the second two-way electromagnetic valve V3 and the third two-way electromagnetic valve V4 respectively, and whether the CO or the volatile organic G5 is introduced into the third mass flow controller Z3 can be controlled. When the first two-way electromagnetic valve V2 is controlled to be opened and the three-way electromagnetic valve V1, the second two-way electromagnetic valve V3 and the third two-way electromagnetic valve V4 are controlled to be closed, the wet air is introduced into the flow tube 20 at this time; when the second two-way electromagnetic valve V3 is controlled to be opened and the three-way electromagnetic valve V1, the first two-way electromagnetic valve V2 and the third two-way electromagnetic valve V4 are controlled to be closed, the wet air containing CO is introduced into the flow tube 20 at this time; when the third two-way electromagnetic valve V4 is controlled to be opened and the three-way electromagnetic valve V1, the first two-way electromagnetic valve V2 and the second two-way electromagnetic valve V3 are controlled to be closed, the wet air containing the volatile organic G5 is introduced into the flow tube 20 at this time. By controlling the wet air of different types and different concentrations to be introduced into the flow tube 20, different kinds of free radicals are generated in the photolysis zone of the flow tube 20. Preferably, the three-way electromagnetic valve V1 is also connected with the high-purity nitrogen G2, and when the three-way electromagnetic valve V1 is opened, the high-purity nitrogen G2 replaces the synthetic air G1 to enter the flow tube 20, and at this time, the oxygen is not contained in the introduced gas, which can be used as a background zero point to calculate the absorption cross section of oxygen. The high-purity nitrogen G2 is also connected with the fourth two-way electromagnetic valve V5, the fifth two-way electromagnetic valve V6 and the sixth two-way electromagnetic valve V7 respectively, the fourth two-way electromagnetic valve V5 controls the high-purity nitrogen G2 to purge the connection flange of the atmospheric OH-HO2-RO2 multi-radical standard source device and the atmospheric radical measurement device, so as to reduce the loss of free radicals on the wall surface of the standard source connection flange 29; the fifth two-way electromagnetic valve V6 controls the high-purity nitrogen G2 to purge the ultraviolet photolysis cavity 13 and the low-pressure mercury lamp, so as to avoid the oxygen in the ultraviolet photolysis cavity 13 from being photolyzed to generate ozone, thereby causing interference; the sixth two-way electromagnetic valve V7 controls the high-purity nitrogen G2 to purge the ultraviolet light source absorption cavity 10, which on the one hand reduces the oxygen interference in the ultraviolet light source absorption cavity 10, and on the other hand adjusts the nitrous oxide concentration by adjusting the supply amount of the high-purity nitrogen G2, so as to realize the dynamic adjustment of the absorption of the ultraviolet light intensity. The nitrous oxide gas G3 is connected with the seventh two-way electromagnetic valve V8 and is connected with the high-purity nitrogen G2 to the second gas mixer H2, the gas flow is controlled by adjusting the seventh mass flow controller Z7, different concentrations of the nitrous oxide gas G3 are introduced into the ultraviolet light source absorption cavity 10, so as to realize the attenuation adjustment of the ultraviolet light intensity. Preferably, the mixer is made of polytetrafluoroethylene material, the number of interfaces can be set according to the number of gas types to be connected, and the multi-path gas can be fully mixed in the mixed gas.

[0101] Preferably, the material of the flow tube 20 is a light-transmitting material that can effectively transmit ultraviolet radiation at 184.9 nm, such as a quartz glass tube (e.g., a JGS-1 far ultraviolet optical quartz glass tube) that can effectively transmit ultraviolet radiation at 184.9 nm, and the flow tube 20 is a quartz tube with an inner diameter of 19 mm, an outer diameter of 22 mm, and a length of 425 mm, which has a transmittance of 90% or more for ultraviolet light at 185 nm. Preferably, a 80-100 mesh, 4 mm thick quartz sand core is provided at a distance of 19 mm from the top to ensure that the gas mixture is fully mixed in the flow tube. The flow tube is inserted into the ultraviolet photolysis cavity 13, and the middle part can be fixed by a flow tube fixing ring and a sealing O-ring, and the lower part can be supported by a flow tube fixing base 15 and fixed by a sealing O-ring. The flow tube fixing ring and the flow tube fixing base 15 are fixed together with the ultraviolet photolysis cavity 13 by screws and sealing O-rings. The upper end of the flow tube 20 can be coaxially connected with the flow tube connecting cap and sealed by a black O-ring. Preferably, the inner and outer surfaces of the flow tube connecting cap are black oxidized, and a flow tube gas inlet is provided on the side surface, which is a 1 / 4 NPT threaded interface, a 1 / 4 NPT external threaded 3 / 8 sleeve joint is installed, and a 3 / 8 PFA pipe is connected together to realize the input of the gas into the flow tube. Preferably, an aluminum flow tube protective sleeve can be provided outside the flow tube 20, which is black oxidized on the inner and outer surfaces, and is fixed to the flow tube 20 fixing ring at the lower end by screws and coaxially connected with the flow tube connecting cap at the upper end. This not only plays a protective role, but also avoids the interference problem caused by sunlight entering the ultraviolet photolysis cavity 13. Preferably, a flow tube gas inlet 23 is provided at the top of the flow tube 20, and a gas unit 24 is connected to the flow tube 20 through the flow tube gas inlet 23. A quartz sand core 21 is provided at the upper part of the flow tube 20 to further ensure the quality of the gas.

[0102] Preferably, the aluminum square shell is in the horizontal direction (X-axis direction), one end is the ultraviolet light incident channel 33, connected with the ultraviolet light source absorption cavity 10, for receiving the adjusted ultraviolet light source radiation; the other end is the ultraviolet light exit channel 34, connected with the standard source control unit 25, for real-time detection of the ultraviolet light source radiation intensity. A stepped hole can be provided in the center of the incident channel, with a large hole depth of 6 mm and a diameter of 50 mm, for guiding the ultraviolet photolysis cavity purge gas to pass through the through hole on the ultraviolet light source absorption cavity 10; the small hole is a rectangular hole with a size of 20 mm 12 mm, which is used as the ultraviolet light incident channel 33 to guide the ultraviolet light into the flow tube 20 to generate OH and HO2 free radicals by photolyzing the humid air therein. Preferably, a movable bolt is provided at the middle position of the smaller circular hole as a movable light window 16, which can be opened or closed by twisting the screw. Correspondingly, a rectangular hole with a size of 20 mm 12mm, as the ultraviolet light exit channel to guide the ultraviolet light out, a large hole is arranged in connection, the depth is 25mm, the diameter is 50mm, preferably, an SM1 internal thread is arranged on the round hole, a plano-convex mirror 9 and a filter 8 are sequentially installed through an SM1 compression ring, preferably, the plano-convex mirror 9 is light-incident on the convex surface, which can focus the outgoing ultraviolet light, the filter 8 is a narrow-band 184.9nm filter, which ensures that only 184.9nm ultraviolet light is detected by the photocell 28.

[0103] A through hole with a diameter of 22mm can be opened in the vertical direction (Y-axis direction), a stepped hole is opened at the upper end (not shown in the figure) for installing the flow tube fixing ring and the flow tube protection sleeve, and a stepped hole is opened at the lower end for installing the flow tube fixing base 15 and the standard source connecting flange 29, the flow tube exhaust gas can flow out from the gap between the stepped hole and the flow tube fixing base 15.

[0104] In the vertical direction (Z-axis direction), a round hole is opened perpendicularly to the outer surface of the ultraviolet photolysis cavity 13 and connected to the middle of the horizontal direction right rectangular hole, which is used to guide the purge gas into the ultraviolet photolysis cavity 13, and a round hole is opened perpendicularly to the outer surface of the ultraviolet photolysis cavity 13 and connected to the middle of the gap between the flow tube fixing base 15 and the ultraviolet photolysis cavity 13, which is used to guide the excess gas in the flow tube 20 out of the ultraviolet photolysis cavity 13. Preferably, the inner and outer surfaces of the ultraviolet photolysis cavity 13 are blackened by oxidation treatment, which can effectively reduce the influence of scattered light; a movable light window 16 is arranged in the ultraviolet light incident channel 33, which can be manually rotated to open or close the light window to cut off the ultraviolet light incident, protecting the photocell or personnel safety.

[0105] Preferably, the reaction gas input channel 35 is a stepped circular hole, with the larger hole having a diameter of 55 mm for fixing the flow tube ring 14. Preferably, two O-ring grooves and screw holes are provided on the surface of the larger hole, with black fluororubber O-rings placed in the grooves to ensure the fixation of the flow tube 20 and the sealing of the ultraviolet photolysis chamber 13. The smaller hole has a diameter of 23 mm to ensure the insertion of the flow tube 20. Preferably, a flow tube protective sleeve 19 is provided around the flow tube 20 and can be fixed to the ultraviolet photolysis chamber with screws, preventing the flow tube from being bumped and avoiding the influence of outdoor light sources. The flow tube protective sleeve 19 is an aluminum cylinder with a flange at one end for direct fixation to the flow tube fixing ring 14, and a straight cylindrical end for connection to the flow tube connecting cap 22 and fixation with a set screw. Preferably, the flow tube connecting cap 22 can be directly fitted onto the flow tube 20 and the flow tube protective sleeve 19 and sealed with O-rings. The flow tube connecting cap 22 is an aluminum cylinder, sealed at the top and with an NPT1 / 4 threaded interface on the side. It can be connected to the gas distribution unit 24 via an NPT1 / 4 external thread to a 3 / 8 compression fitting. The lower end has a stepped hole with O-ring grooves on the two steps. After the O-rings are installed, they are sealed and fixed together with the flow tube protective sleeve 19 and the flow tube 20. One end of the reaction gas output channel 36 is sealed and fixed to the flow tube 20 via the flow tube fixing base 15, and the other end is connected to the standard source connecting flange 29 via screws. The reaction gas output channel 36 is a stepped circular hole. The larger circular hole has a diameter of 50mm and is used to install the flow tube fixing base 15. The smaller circular hole has a diameter of 23mm to ensure the insertion of the flow tube 20. Preferably, a through hole with a diameter of 4mm is provided in the middle of the larger circular hole as the flow tube vent 18. Excess gas is vented by connecting an NPT to a 1 / 4 compression fitting and a vacuum pump (not shown in the figure). Preferably, a threaded hole with an O-ring groove is provided on the larger circular hole surface to ensure that the flow tube fixing base 15 can be directly screwed into the threaded hole for fixing and sealing. The flow tube fixing base 15 is cylindrical, with one end being externally threaded so that it can be directly screwed into the reaction gas output channel 36 of the ultraviolet photolysis chamber 13, and the other end being chamfered to facilitate the venting of the generated standard gas. The outer diameter is 40mm, the inner diameter is 23mm, and the inner wall surface is provided with two O-ring grooves to ensure that the flow tube 20 can be inserted, fixed, and sealed. The standard source connection flange 29 is an aluminum cylindrical type, with both the inner and outer surfaces treated with black anodizing to reduce the influence of outdoor light sources such as sunlight. The upper flange face is provided with an O-ring groove and is fixed to the ultraviolet photolysis cavity 13 by screws. The lower flange face is connected to the gas expansion laser-induced fluorescence atmospheric free radical measurement system 31. A pair of 1 / 8 NPT threaded holes are provided opposite each other in the middle position as the purge gas inlet 30 of the standard source connection flange, which is connected to the gas distribution unit 24 to provide high-purity nitrogen gas and reduce the loss of free radicals on the wall surface.

[0106] Preferably, the aluminum cylindrical shell of the UV light source absorption cavity 10 is provided with a stepped hole (not shown in the figure) in the middle for mounting the flat window mirror 11, preferably, an O-ring groove is provided at the step and an SM1 internal thread is provided on the inner wall, the flat window mirror 11 can be fixed on the step by an SM1 compression ring and sealed by an O-ring. In the vertical direction, a 1 / 8NPT external thread hole is provided in the middle of each of the two window mirrors as an entrance for nitrous oxide gas G3, when different concentrations of nitrous oxide gas G3 are introduced through the gas distribution unit 24, the 184.9nm ultraviolet light can be quantitatively absorbed, thereby adjusting the radiation intensity of the ultraviolet light source on the photolysis zone of the flow tube 20. A plurality of through holes with a diameter of 1mm are provided between the inner and outer walls of the UV light source absorption cavity 10 as purge gas channels for removing ozone generated by scattered light radiation from the UV light source absorption cavity 10.

[0107] More preferably, the aluminum cylindrical shell of the UV light source absorption cavity 10 is provided as a flange sleeve type aluminum stepped cylinder, one end is sealingly connected with the UV light source adjustment cavity 5, the other end is sealingly connected with the UV photolysis cavity 13 through a screw and an O-ring. Preferably, the inner and outer surfaces are blackened to reduce the influence of scattered light. The middle of the flange sleeve type aluminum stepped cylinder is a through hole as a nitrous oxide absorption reaction zone, a 1 / 8NPT threaded hole 12 is provided opposite to each other at the middle position of the through hole as an entrance for nitrous oxide, a 1 / 8NPT turn-to-lock fitting is installed to introduce nitrous oxide gas G3 into the middle through hole reaction zone and evacuate it; the two ends are stepped holes, an O-ring groove is provided on the step surface for compression sealing with the flat window mirror 11, an SM1 internal thread is provided on the step wall, an SM1 external thread compression ring can be screwed in to fix the flat window mirror 11, six through holes with a diameter of 1.5mm are uniformly distributed between the internal thread and the outer wall as channels for the UV photolysis cavity purge gas, which is introduced from the UV photolysis cavity 13 to the UV light source adjustment cavity 5.

[0108] Preferably, the movable light window 16 is a circular plug with a diameter of 20mm, a through hole with a diameter of 15mm is provided in the center, which is in communication with the UV light incident channel 33, can be directly inserted into the UV photolysis cavity 13 and sealed by an O-ring, and the UV light can be passed or isolated by rotating the plug. Alternatively, the UV photolysis cavity purge gas inlet 17 is a circular hole with a diameter of 2mm, which is in communication with the UV light exit channel 34, can provide high-purity nitrogen gas to realize full-range purging of the UV light channel. Alternatively, the flow tube evacuation port 18 is a circular hole with a diameter of 4mm, which is in communication with the reaction gas output channel 36.

[0109] In the embodiment, the standard source control unit 25 is further connected with a microcomputer integrated machine 26 and an ultraviolet light source power supply 27. The ultraviolet light source power supply 27 is installed in the standard source control unit 25 and connected with an ultraviolet light source (not shown in the figure) through a waterproof aviation plug. The microcomputer integrated machine 26 is installed in the standard source control unit 25 and connected with the gas distribution unit 24, the photocell 28 and the ultraviolet light source power supply 27 in an electrical circuit.

[0110] Preferably, the standard source control unit 25 is an aluminum sealed box (not labeled in the figure) which is fixed with the ultraviolet photolysis cavity 13 through screws and a sealing ring. The center of the photocell 28 is coaxial with the exit channel 34 of the ultraviolet photolysis cavity. Preferably, the center of the photosensitive surface of the photocell 28 is on the focal point of the exit channel plano-convex lens 9, so that the photocell can completely receive the exit ultraviolet light. Preferably, the microcomputer integrated machine 26 has an 8-way relay output, which can control the opening and closing of the electromagnetic valve of the gas distribution unit 24 and the ultraviolet light source power supply 27. The microcomputer integrated machine 26 has a 1-way 485 communication interface, which can communicate with the mass flow controller of the gas distribution unit 24 and the high-precision dew point instrument L, write or read control data in real time. The microcomputer integrated machine 26 has 2-way 18-bit analog voltage input channels, which can collect photocell 28 signals in real time. The microcomputer integrated machine 26 has a 4.3-inch capacitive touch screen and a U disk interface, which can realize convenient interaction.

[0111] More specifically, the standard source control unit 25 is set as an aluminum cuboid shell, which is hollowed inside, can accommodate the microcomputer all-in-one machine 26, the ultraviolet light source power supply 27 and the phototube 28; one side is open, and the shell is sealed by aluminum plate through screws and silica gel gasket. Preferably, the inside and outside surfaces of the shell are black oxidized to reduce light scattering. The cuboid shell is provided with a 15mm diameter circular hole on one side and is fixed on the ultraviolet photolysis cavity 13 by screws, and the center of the circular hole is on the center axis of the ultraviolet photolysis cavity 13. Preferably, an O-ring groove is provided on the connecting surface of the ultraviolet photolysis cavity 13 and the standard source control unit 25 to ensure the sealing of the standard source control unit 25 and the ultraviolet photolysis cavity 13. The other side of the cuboid shell is provided with a rectangular screen mounting port for mounting the microcomputer all-in-one machine 26. The microcomputer all-in-one machine 26 is a general type, equipped with a capacitive touch screen, a 485 communication interface, an analog input / output port and a digital input / output port, can be connected with the gas distribution unit 24 through a serial port line to realize automatic or manual control of the gas circuit, can be connected with the phototube to realize phototube signal acquisition, storage and display, and can be connected with the ultraviolet light source power supply 27 to realize the opening or closing of the ultraviolet light source 2. The ultraviolet light source power supply 27 is fixed in the cuboid shell and can supply power to the ultraviolet light source 2 to realize the opening or closing of the ultraviolet light source 2. Preferably, the microcomputer all-in-one machine 26, the ultraviolet light source power supply 27 and the ultraviolet light source 2 are connected through waterproof aviation plugs to ensure the sealing of the standard source control unit 25, so as to be suitable for field environment. The phototube 28 is a commercial general end window type (model R5764) which has a significant response to 185nm ultraviolet light and can monitor the radiation intensity of the ultraviolet light passing through the flow tube. The center of the phototube photocathode face is on the center axis of the ultraviolet photolysis cavity 13 and is ensured to be at the focal point of the plano-convex lens, so that the ultraviolet light passing through the flow tube can be focused on the phototube and detected.

[0112] Although the embodiments of the present application are disclosed for illustrative purposes, those skilled in the art can understand that various alternatives, changes and modifications are possible without departing from the spirit and scope of the present application and the appended claims, therefore, the scope of the present application is not limited to the disclosed content of the embodiments.

Claims

1. A method for generating a hydroxyl radical (OH-), hydrogen peroxide radical (HO2-), organic peroxide radical (RO2) and polyradical standard source, characterized by: It comprises the following steps: (1) Control the dry air, wet air and volatile organic compounds or carbon monoxide into the flow tube (20) by mass flow controller, and monitor the water vapor content of the gas entering the flow tube (20) by high-precision dew point instrument L in real time; (2) The flow tube (20) is fixed in the ultraviolet photolysis cavity (13), and the gas in the flow tube (20) is irradiated by 184.9 nm ultraviolet light, in which O2 and H2O are synchronously photolyzed to generate ozone, hydroxyl radical OH and hydroperoxy radical HO2 respectively; when CO is introduced, CO reacts with hydroxyl radical OH to convert into hydroperoxy radical HO2 completely; when volatile organic compounds are introduced, volatile organic compounds react with hydroxyl radical OH to generate specific types of organic peroxy radicals RO2 completely; (3) Real-time detection of 184.9 nm ultraviolet radiation intensity and measurement of ozone concentration at the center of the flow tube (20) by ozone analyzer, establishment of the functional relationship between the ozone concentration at the center of the flow tube (20) and the ultraviolet radiation intensity, combination of the water vapor concentration data obtained by the high-precision dew point instrument L and the absorption cross-section values of O2 and H2O at 184.9 nm, and calculation of the concentrations of hydroxyl radical OH, hydroperoxy radical HO2 and organic peroxy radical RO2 generated.

2. Hydroxyl radical OH-, hydroperoxyl radical HO2-, organic peroxy radical RO2, and multiradical standard source generating device for realizing the method as claimed in claim 1, characterized in that: The device comprises an ultraviolet light source mounting cavity (1), an ultraviolet light source (2), an ultraviolet light source adjusting cavity (5), an ultraviolet light source absorption cavity (10), an ultraviolet photolysis cavity (13), a flow tube (20), a gas distribution unit (24), a standard source control unit (25) and a phototube (28), the ultraviolet light source (2) is closely mounted on the ultraviolet light source mounting cavity (1), the ultraviolet light source mounting cavity (1), the ultraviolet light source adjusting cavity (5), the ultraviolet light source absorption cavity (10), the ultraviolet photolysis cavity (13) and the standard source control unit (25) are closely connected in sequence along the horizontal direction, the ultraviolet light generated by the ultraviolet light source (2) can pass through the ultraviolet light source adjusting cavity (5), the ultraviolet light source absorption cavity (10), the ultraviolet photolysis cavity (13) and the standard source control unit (25) in sequence and be detected by the phototube (28) therein, the ultraviolet light source adjusting cavity (5) can collimate, focus and adjust the energy of the ultraviolet light generated by the ultraviolet light source (2), the ultraviolet light source absorption cavity (10) can absorb ultraviolet light and thus weaken the ultraviolet light radiation intensity quantitatively, the ultraviolet photolysis cavity (13) can synchronously photolyze the gas in the flow tube (20) to generate O3, hydroxyl radical OH, hydroperoxy radical HO2 and different types of organic peroxy radicals RO2, the gas distribution unit (24) can accurately control the gas flow and switch different gas supplies for the flow tube (20), the ultraviolet photolysis cavity (13) and the ultraviolet light source absorption cavity (10), the standard source control unit (25) can provide a human-computer interaction interface and communicate with and control the gas distribution unit (24), the ultraviolet light source (2) and the phototube (28), and the phototube (28) can monitor the ultraviolet light source radiation intensity in real time and output the results to the standard source control unit for display and storage.

3. The apparatus of claim 2, wherein: The ultraviolet light source (2) is closely connected with the ultraviolet light source mounting cavity (1) through the ultraviolet light source fixing member (3), the ultraviolet light source mounting cavity (1) is an aluminum shell with an open end and a hollow interior, the ultraviolet light source (2) includes a lamp tube, the lamp tube of the ultraviolet light source (2) is arranged in the hollow interior of the aluminum shell, and the ultraviolet light source (2) is directly inserted into the ultraviolet light source mounting cavity (1) and is sealed and fixed through the ultraviolet light source fixing member (3); Alternatively, the ultraviolet light source (2) can continuously and stably emit 184.9 nm ultraviolet light.

4. The apparatus of claim 2, wherein: The ultraviolet light source adjusting cavity (5) includes an aluminum flange type shell with open ends and a hollow interior, a lens mounting member (6), a diaphragm (7), a filter (8) and a plano-convex lens (9), the aluminum flange type shell is closely connected with one side of the open end of the ultraviolet light source mounting cavity (1), the diaphragm (7), the filter (8) and the plano-convex lens (9) are sequentially connected in the horizontal direction in the hollow interior of the aluminum flange type shell through the lens mounting member (6).

5. The apparatus of claim 2, wherein: The ultraviolet light source absorbing cavity (10) includes an aluminum cylindrical shell with open ends and a hollow interior, a plane window mirror (11) and a nitrous oxide inlet and outlet (12), the aluminum cylindrical shell is closely coaxially connected with the aluminum flange type shell of the ultraviolet light source adjusting cavity (5), the plane window mirror (11) is arranged in the hollow interior of the aluminum cylindrical shell, and two plane window mirrors (11) are coaxially and symmetrically arranged in the horizontal direction, the nitrous oxide inlet and outlet (12) is connected with the gas distribution unit (24) through a pipeline.

6. The apparatus of claim 2, wherein: The ultraviolet photolysis cavity (13) is an aluminum cube shell, and holes are arranged on the six faces thereof, which are respectively used as ultraviolet light channels, reaction gas channels and purge / evacuation gas channels, wherein the ultraviolet light channels and the reaction gas channels are vertically orthogonal, and the purge / evacuation gas channels are arranged in a third direction.

7. The apparatus of claim 2, wherein: The gas distribution unit (24) includes solenoid valves, mass flow controllers, a bubbler Q, a gas mixer, a high-precision dew point instrument L and a steel cylinder gas, and by switching the solenoid valves and setting the mass flow controller flow setting value, the synthesized air, CO or VOCs of different humidities are controlled to enter the flow pipe (20), or the purge gas is controlled to enter the ultraviolet photolysis cavity (13), or the nitrous oxide gas G3 of different concentrations is controlled to enter the ultraviolet light source absorbing cavity (10).

8. The device of any one of claims 2 to 7, wherein: The standard source control unit (25) is provided with a microcomputer all-in-one machine (26), an ultraviolet light source power supply (27) and a photocell (28), wherein the microcomputer all-in-one machine (26) is electrically connected with the gas distribution unit (24), the photocell (28) and the ultraviolet light source power supply (27), and the ultraviolet light source power supply (27) is connected with the ultraviolet light source through a waterproof aviation plug.

9. Use of the device according to any one of claims 2 to 7 in the generation of hydroxyl radical OH, hydroperoxyl radical HO2 and organic peroxyl radical RO2 multi-radicals.

10. Use of the device according to any one of claims 2 to 7 in an atmospheric radical measurement instrument.

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