Aerosol single microdroplet monitoring device and method in real atmosphere

Abstract

The invention relates to an aerosol single-droplet monitoring device and method in a real atmosphere, belongs to the field of aerosol single-droplet detection, and solves the problem that an existing aerosol single-droplet monitoring device cannot monitor the property change of a single droplet in the real atmosphere or the detection error of the saturated vapor pressure of the single droplet is large. A gas path system of the device comprises a real atmosphere gas path system, the real atmosphere gas path system is communicated with a single-droplet optical tweezers suspension device, a microdroplet pumping system is communicated with the single-droplet suspension system, and a light beam coupling system is respectively communicated with the single-droplet optical tweezers suspension device, a signal detection system and a microdroplet detection device; the real atmosphere gas path system comprises a first gas path and a second gas path, the first gas path and the second gas path are both communicated with real atmosphere, the first gas path and the second gas path are respectively communicated with the single-droplet optical tweezers suspension device, the second gas path is provided with a gas pumping device, and the gas pumping device is a vacuum pump or an air compressor; the device can monitor the property change of the single liquid drop in the real atmosphere.

Description

Technical Field

[0001] The present invention relates to the technical field of aerosol single droplet detection, and in particular to an aerosol single droplet monitoring device and method in a real atmospheric atmosphere. Background Art

[0002] Atmospheric aerosols are effective micro-reaction sites for the transformation of primary pollutants into secondary pollutants in the atmosphere. Monitoring of the interface and bulk reaction processes of droplets is also an important means to study the formation process of atmospheric haze pollution.

[0003] However, the existing aerosol single droplet monitoring device is usually connected to a gas cylinder, and the pure gas (such as nitrogen) in the gas cylinder is used as the environmental gas for monitoring the single droplet, and a specific reaction gas is introduced to monitor the property changes of the single droplet in the mixed gas of the reaction gas and the environmental gas. However, the mixed gas of the reaction gas and the environmental gas is still quite different from the real atmospheric atmosphere. The composition of the real atmosphere is complex, and its composition will change due to light. The dark reaction property changes of a single droplet in the mixed gas of the reaction gas and the environmental gas cannot clearly indicate its property changes in the real atmosphere.

[0004] In addition, accurate measurement of saturated vapor pressure parameters is essential for understanding PM 2.5 An important physical and chemical parameter of the driving force of secondary organic aerosol generation during explosive growth. By real-time and in-situ observation of the changes in particle size and composition of a single droplet in a specific atmosphere, the problem of high-quality data measurement of key physical and chemical parameters in the gas-particle distribution process of volatile substances can be solved. In order to reveal the key driving force of secondary organic aerosol generation and growth in atmospheric fine particulate pollution, it is of great significance to develop a single droplet saturated vapor pressure measurement device for volatile substances.

[0005] The existing aerosol single droplet monitoring devices and methods have large errors in the detection results of the saturated vapor pressure parameters of single droplets containing volatile components. Summary of the invention

[0006] In view of the above analysis, the embodiments of the present invention are intended to provide an aerosol single droplet monitoring device and method in a real atmospheric atmosphere, so as to solve at least one of the following problems existing in existing aerosol single droplet monitoring devices: (1) it is impossible to monitor the property changes of a single droplet in the real atmosphere; (2) the detection result of the saturated vapor pressure parameter of a single droplet has a large error.

[0007] On the one hand, the present invention provides an aerosol single droplet monitoring device in a real atmospheric atmosphere, the device comprising a single droplet optical tweezers suspension device, an air path system, a droplet pumping system, a beam coupling system, a signal detection system and a droplet detection device;

[0008] Wherein, the gas circuit system includes a real atmospheric gas circuit system, the real atmospheric gas circuit system is connected to the single droplet optical tweezers suspension device, the droplet pumping system is connected to the single droplet suspension system, and the beam coupling system is respectively connected to the single droplet optical tweezers suspension device, the signal detection system and the droplet detection device;

[0009] The real atmosphere gas path system comprises a first gas path and a second gas path, the first gas path and the second gas path are both connected to the real atmosphere, the first gas path and the second gas path are respectively connected to the single droplet optical tweezers suspension device, and a pumping device is arranged on the second gas path, and the pumping device is a vacuum pump or an air compressor;

[0010] The single droplet optical tweezers suspension device comprises a sample pool, which comprises a concentric outer ring wall and an inner ring wall, wherein the outer ring wall is connected to one side of the inner ring wall, and a single droplet inlet penetrating the outer ring wall and the inner ring wall is arranged at the connection; the outer ring wall and the inner ring wall are both provided with a plurality of gas inlets and gas outlets penetrating the ring walls and arranged at intervals, and the gas inlet and gas outlet on the outer ring wall are staggered with the gas inlet and gas outlet on the inner ring wall;

[0011] The diameter of the gas inlet and the diameter of the gas outlet are both smaller than the diameter of the single droplet inlet.

[0012] Preferably, a filtering device is also provided on the first gas path.

[0013] Preferably, gas composition analyzers are provided on both the first gas path and the second gas path.

[0014] Preferably, a temperature and humidity recorder is also provided on the first gas path.

[0015] Preferably, a mass flow meter and a flow valve are also provided on the second gas path.

[0016] Preferably, the gas circuit system further comprises a humidity regulating gas circuit system, and the humidity regulating gas circuit system is connected to the droplet pumping system.

[0017] Preferably, the distance between the outer annular wall and the inner annular wall is 2-3 mm.

[0018] Preferably, a quartz glass sheet is disposed at the bottom of the sample cell, and an anionic surfactant layer is disposed on the quartz glass sheet.

[0019] Preferably, the anionic surfactant layer has a thickness of 0.1-0.2 mm.

[0020] On the other hand, the present invention also provides a method for monitoring aerosol single droplets in a real atmosphere, using the above-mentioned aerosol single droplet monitoring device in a real atmosphere, the method comprising:

[0021] The droplet pumping system pumps the aerosol into the sample pool of the single droplet optical tweezers suspension device in the form of a single droplet;

[0022] The laser emitted by the beam coupling system is used as a trapping beam to capture a single droplet in the sample cell and suspend it using the optical tweezers technique;

[0023] One of the first gas path and the second gas path is used as an inlet gas path, and the other gas path is used as an outlet gas path, and real air is introduced into the sample cell through the inlet gas path, and the real air reacts with specific components in the single droplet when flowing through the sample cell;

[0024] The scattered light signal of a single droplet is input into the signal detection system and the droplet detection device respectively. The property changes of the single droplet during the reaction process in the real atmospheric atmosphere are monitored according to the light signal data, and the saturated vapor pressure is calculated according to the numerical change of the single droplet radius before and after the single droplet reaction.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] 1. The present invention sets a real gas gas path system on the aerosol single droplet monitoring device, the first gas path and the second gas path are directly connected to the real atmosphere of the external environment, the real atmosphere is directly introduced into the sample pool through the pump gas device, the real atmosphere is introduced into the sample pool through one of the first gas path and the second gas path, and the real atmosphere after the reaction is discharged through the other gas path, and the property changes of the single droplet in the reaction process under the real atmosphere are monitored by the signal detection system and the droplet detection device.

[0027] 2. The sample pool of the present invention comprises an outer ring wall and an inner ring wall, a single droplet inlet penetrating the outer ring wall and the inner ring wall is arranged at the connection of the outer ring wall and the inner ring wall, a plurality of gas inlets and gas outlets penetrating the ring wall and arranged at intervals are arranged on the outer ring wall and the inner ring wall, the gas inlet and gas outlet on the outer ring wall are staggered with the gas inlet and gas outlet on the inner ring wall, this structure can make the gas enter and discharge the sample pool uniformly, and ensure the stability of the air pressure in the sample pool, so that the optical tweezers can stably suspend the single droplet; in addition, the uniform entry and discharge of the gas into the sample pool can avoid excessively high or low local air pressure, reduce the uneven distribution of droplets when entering the sample pool due to uneven air pressure, and effectively solve the problem that uneven air pressure may cause droplets to deposit on the wall; moreover, the stable air pressure in the sample pool helps to maintain the suspension state of the single droplet, reduce the contact between the droplet and the wall caused by air pressure fluctuations, and thus reduce the error influence of the wall effect on the saturated vapor pressure;

[0028] The diameter of the gas inlet and the diameter of the gas outlet are both smaller than the diameter of the single droplet inlet. When a single droplet is pumped into the sample pool from the single droplet inlet, the turbulence effect of the aerosol droplets in the sample pool can be generated and enhanced. The turbulence can enhance the mixing and movement of the droplets in the sample pool, and reduce the probability and possibility of the droplets depositing on the inner wall. The rapid and swirling airflow does not simply go from the inlet to the outlet, but approaches the center of the sample pool (i.e., the laser focusing center) by virtue of the turbulent effect. At the same time, the swirling effect can also increase the probability of the airflow outside the focusing center returning to the focus, thereby increasing its capture efficiency, reducing the probability of aerosol droplets depositing on the inner wall of the sample pool, and reducing the error influence of the wall effect on the saturated vapor pressure.

[0029] 3. A quartz glass sheet coated with an anionic surfactant is disposed at the bottom of the sample pool of the present invention. The anionic surfactant reduces the surface tension of the spherical droplets and causes the droplets at the bottom of the sample pool to no longer be deposited in a spherical form, but to spread directly on the bottom of the sample pool, thereby avoiding the saturated vapor pressure error caused by the curved surface pressure brought about by the curved surface structure of the droplets containing volatile chemical components at the bottom of the sample pool.

[0030] 4. The present invention provides a droplet beam device in the droplet pumping system. When the aerosol droplets pass through the droplet beam device, the droplet beam device changes the droplets from an aggregated state into a monodispersed single string of droplets that enter the sample pool one by one.

[0031] 5. A stop valve is arranged between the aerosol generator and the droplet beam device of the present invention. When the droplets enter the droplet beam device, the stop valve can be closed, and a dilution gas (such as nitrogen) can be introduced into the droplet beam device through a humidity regulating gas path system to dilute the droplets in the droplet beam device, thereby further promoting the droplet beam device to change the droplets from an aggregated state into a monodispersed single string of droplets that enter the sample pool one by one.

[0032] 6. In the method of the present invention, after the single droplet is suspended by the optical tweezers technique, dry gas and / or wet gas is introduced into the sample pool through the humidity regulating gas circuit system, the humidity in the sample pool is reduced to below the weathering point humidity of the chemical components in the droplet, and the droplets on the inner wall of the sample pool are weathered and crystallized, and then the humidity regulating gas circuit system is closed. After the humidity regulating gas circuit system is closed, the real atmosphere is introduced into the sample pool, and the humidity will be adjusted to the humidity of the real atmosphere as the real atmosphere is continuously introduced. In the process of weathering and crystallization, the volatile components in the droplets deposited on the wall of the device have volatilized. When the humidity in the sample pool is increased to the humidity of the real atmosphere, the crystallization on the wall of the device absorbs water molecules in the environment to form a solid-liquid mixture. The liquid phase in the solid-liquid mixture is only the adsorbed water molecules, and no longer has the volatile organic components in the aerosol droplets. In this process, the volatile components in the single droplet suspended by the optical tweezers remain unchanged, thereby effectively avoiding the influence of the volatile components in the droplets deposited on the wall on the saturated vapor pressure of the single droplet suspended by the optical tweezers.

[0033] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0035] Figure 1 The aerosol single droplet monitoring device in the real atmosphere of the present invention;

[0036] Figure 2 It is a schematic diagram of the sample pool structure of the present invention;

[0037] Figure 3 A structural discrete diagram of the droplet beam device of the present invention (the aperture and the gasket are separately shown outside);

[0038] Figure 4 is a cross-sectional view of the droplet beam device of the present invention;

[0039] Figure 5 It is a schematic diagram of the monodisperse action principle of the droplet beam device of the present invention;

[0040] Figure 6 The variation trend of droplet size over time under the real atmospheric background and the curve diagram of real gas humidity variation in the outlet gas path of Example 2;

[0041] Figure 7 The PM monitored by Beijing Liangxiang Monitoring Station at the corresponding time of Example 2 2.5 、PM 10 , SO2, NO2 and O3 concentration changes.

[0042] Reference numerals:

[0043] 1-single droplet optical tweezers suspension device; 101-microscope objective lens; 102-sample pool; 1021-outer ring wall; 1022-inner ring wall; 1023-single droplet inlet; 1024-gas inlet; 1025-gas outlet; 103-illumination light source; 2-gas path system; 201-first gas path; 2011-filter device; 2012-temperature and humidity recorder; 202-second gas path; 2021-pumping device; 2022-mass flowmeter; 2023-flow valve; 203-gas composition analyzer; 204-humidity adjustment gas path system; 204 1-gas generating device; 2042-flow meter; 3-droplet pumping system; 301-aerosol generator; 302-stop valve; 303-droplet beam device; 3031-pipeline; 3032-aperture; 3033-gasket; 3034-clamp; 3035-threaded cover; 4-beam coupling system; 401-laser; 402-focusing lens; 403-semi-transparent and semi-reflective mirror; 404-total reflection mirror; 5-signal detection system; 501-optical imaging camera; 502-Raman spectrometer; 503-data processing unit; 6-droplet detection device. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0045] The inventors found in their research that the existing aerosol single droplet monitoring device cannot monitor the property changes of a single droplet in the real atmosphere, because the existing aerosol single droplet monitoring device can only be connected to a gas cylinder and cannot be directly connected to the atmosphere; and the existing aerosol single droplet monitoring device and method have large errors in the detection results of the saturated vapor pressure parameters of a single droplet containing volatile components because of the wall effect of the droplet in the sample pool, which is specifically as follows: after the aerosol droplets are pumped into the sample pool, the droplets will be deposited on the inner wall and bottom of the sample pool due to the sedimentation effect and the wall impact effect caused by the droplet gravity and the pumping impulse. After the aerosol droplets are deposited, the droplets deposited on the inner wall and bottom and the droplets captured by the laser are basically spherical in shape, and the curved surface of the spherical droplets can enhance the volatilization pressure of the droplets containing volatile chemical components, causing the measured saturated vapor pressure of the droplets to reach the threshold first, thereby making the measured value of the saturated vapor pressure much higher than the actual saturated vapor pressure value, that is, the detection result of the saturated vapor pressure has a large error.

[0046] Based on this, the present invention provides an aerosol single droplet monitoring device in a real atmospheric atmosphere, such as Figure 1 As shown, the device includes a single droplet optical tweezers suspension device 1, a gas path system 2, a droplet pumping system 3, a beam coupling system 4, a signal detection system 5 and a droplet detection device 6;

[0047] The gas circuit system 2 includes a real atmospheric gas circuit system, the real atmospheric gas circuit system is connected to the single droplet optical tweezers suspension device 1, the droplet pumping system 3 is connected to the single droplet suspension system 1, and the beam coupling system 4 is respectively connected to the single droplet optical tweezers suspension device 1, the signal detection system 5 and the droplet detection device 6;

[0048] The real atmosphere gas path system comprises a first gas path 201 and a second gas path 202, both of which are connected to the real atmosphere, and the first gas path 201 and the second gas path 202 are connected to the single droplet optical tweezers suspension device 1 respectively, and a pumping device 2021 is provided on the second gas path 202, and the pumping device is a vacuum pump or an air compressor;

[0049] The single droplet optical tweezers suspension device 1 includes a sample pool 102, such as Figure 2 As shown, the sample pool 102 includes a concentric outer annular wall 1021 and an inner annular wall 1022, the outer annular wall 1021 is connected to one side of the inner annular wall 1022, and a single droplet inlet 1023 penetrating the outer annular wall 1021 and the inner annular wall 1022 is provided at the connection; the outer annular wall 1021 and the inner annular wall 1022 are provided with a plurality of gas inlets 1024 and gas outlets 1025 penetrating the annular walls and arranged at intervals, and the gas inlet 1024 and gas outlet 1025 on the outer annular wall 1021 are staggered with the gas inlet 1024 and gas outlet 1025 on the inner annular wall 1022;

[0050] The diameter of the gas inlet 1024 and the diameter of the gas outlet 1025 are both smaller than the diameter of the single droplet inlet 1023 .

[0051] Compared with the prior art, the present invention sets a real gas gas path system on the aerosol single droplet monitoring device, the first gas path and the second gas path are directly connected to the real atmosphere of the external environment, the real atmosphere is directly introduced into the sample pool through the pump gas device, and the property changes of the single droplet in the reaction process under the real atmosphere are monitored through the signal detection system and the droplet detection device. In addition, the structure of the sample pool of the present invention can reduce the error influence caused by the wall effect on the saturated vapor pressure.

[0052] Exemplarily, the air pumping device 2021 is disposed at an end of the second air path 202 close to the real atmosphere.

[0053] When the air pump device 2021 is a vacuum pump, the first air path 201 is further provided with a filter device 2011, and the filter device 2011 is provided at one end of the first air path 201 close to the real atmosphere. During implementation, the first air path 201 is the air inlet path, and the second air path 202 is the air outlet path. When the vacuum pump is started, the real atmosphere in the environment passes through the filter device 2011 and enters the sample pool 102, and then is discharged through the second air path 202. The filter device is used to filter solid components such as dust and particulate matter in the real atmosphere.

[0054] When the air pump device 2021 is an air compressor, the air compressor itself has a filtering function, and there is no need to set up a filtering device. During implementation, the second air path 202 is the air inlet path, and the first air path 201 is the air outlet path. When the air compressor is started, the real atmosphere in the environment enters the sample pool 102 after passing through the air compressor, and then is discharged through the first air path 201.

[0055] Exemplarily, a gas composition analyzer 203 is provided on both the first gas path 201 and the second gas path 202. The gas composition analyzers on the first gas path and the second gas path monitor the changes in the real atmosphere composition before and after the reaction, and the components consumed and generated when the droplets react are inferred based on the changes in the atmosphere composition (the components reduced in the real atmosphere are consumed when the droplets react, and the components increased in the real atmosphere are generated when the droplets react).

[0056] Exemplarily, a temperature and humidity recorder 2012 is also provided on the first gas path 201. The temperature and humidity recorder 2012 is arranged near the single-droplet optical tweezers suspension device 1 and is used to record the temperature or humidity of the single-droplet optical tweezers suspension device 1 (it is inconvenient to set a humidity recorder inside the single-droplet optical tweezers suspension device 1).

[0057] It should be noted that the filter device 2011 , the gas composition analyzer 203 , and the temperature and humidity recorder 2012 on the first gas path 201 are sequentially arranged in a direction close to the single-droplet optical tweezers suspension device 1 .

[0058] Exemplarily, the second gas path 202 is further provided with a mass flow meter 2022 and a flow valve 2023, which are used to record the flow of the real atmosphere and adjust the flow, respectively.

[0059] It should be noted that the gas pump device 2021 , the flow valve 2023 , the mass flow meter 2022 and the gas composition analyzer 203 on the second gas path 202 are sequentially arranged in a direction close to the single droplet optical tweezers suspension device 1 .

[0060] For example, a temperature and humidity recorder ( Figure 1 ), used to monitor the humidity before the real atmosphere reaction.

[0061] Exemplarily, the gas circuit system 2 further includes a humidity regulating gas circuit system 204 , and the humidity regulating gas circuit system 204 is connected to the droplet pumping system 3 .

[0062] Specifically, the humidity regulating gas circuit system 204 includes a gas generating device 2041 and a flow meter 2042. Dry gas and / or wet gas are passed into the sample cell through the humidity regulating gas circuit system 204 to adjust the ambient humidity in the sample cell and reduce the influence of the vessel wall effect on the saturated vapor pressure, as described in detail below.

[0063] It should be noted that the outer annular wall 1021 and the inner annular wall 1022 are coaxially arranged and share a bottom surface.

[0064] Exemplarily, the distance between the outer annular wall 1021 and the inner annular wall 1022 is 2-3 mm.

[0065] Exemplarily, the diameter of the single droplet inlet 1023 is 3-4 times the diameter of the gas inlet 1024 , and the diameter of the single droplet inlet 1023 is 2-2.5 times the diameter of the gas outlet 1025 .

[0066] Exemplarily, the diameter of the gas inlet 1024 is smaller than the diameter of the gas outlet 1025 .

[0067] Exemplarily, the diameter of the single droplet inlet 1023 is 3 mm, the diameter of the gas inlet 1024 is 1.0 mm, and the diameter of the gas outlet 1025 is 1.5 mm.

[0068] Exemplarily, a quartz glass sheet (not shown) is disposed at the bottom of the sample pool 102, and an anionic surfactant layer is disposed on the quartz glass sheet. The anionic surfactant reduces the surface tension of the spherical droplets, and makes the droplets at the bottom of the sample pool no longer deposit in a spherical form, but directly spread on the bottom of the sample pool, thereby avoiding the saturated vapor pressure error caused by the curved surface pressure brought by the curved surface structure of the droplets containing volatile chemical components at the bottom of the sample pool.

[0069] Exemplarily, the anionic surfactant layer has a thickness of 0.1-0.2 mm.

[0070] Exemplarily, the anionic surfactant is sodium fatty alcohol ether sulfate and / or sodium dodecyl sulfate.

[0071] Exemplarily, the single droplet optical tweezers suspension device 1 further includes a microscope objective 101 and an illumination light source 103, wherein the microscope objective 101 is disposed between the sample pool 102 and the beam coupling system, and the illumination light source 103 is disposed above the sample pool 102. After the light beam from the beam coupling system reaches the microscope objective 101, the microscope objective 101 introduces the light beam into the sample pool 102 for optical tweezers. The illumination light source 103 is used to image the optical signal of the single droplet in the droplet detection device 6 and the signal detection system 5.

[0072] It should be noted that the illumination light source 103 can introduce specific lighting conditions or introduce natural light.

[0073] Exemplarily, the illumination light source 103 may introduce light of different wavelengths, so as to monitor the reaction of a single droplet under the conditions of light of different wavelengths.

[0074] It should be noted that the droplets deposited on the inner wall of the sample pool cannot be solved directly by applying anionic surfactants. This is because, in addition to the single droplet inlet 1023, the structure of the sample pool 102 of the present invention also includes a gas inlet 1024 and a gas outlet 1025. If the anionic surfactant is applied to the inner wall surface, when the humidity in the sample pool 102 increases, water molecules and the anionic surfactant will be emulsified on the inner wall of the sample pool 102 to produce foam, which may cause pore blockage, and when the foam collides and accumulates to a certain weight, it cannot hang on the wall and will slide to the quartz glass sheet at the bottom of the sample pool. If it slides to the vicinity of the focusing position, it will cause a macroscopic morphological effect of suspended droplet imaging. If it slides to the focusing center of the microscope objective 101, it will affect the refraction effect and cause the suspended droplets to fall.

[0075] Exemplarily, the droplet pumping system 3 includes an aerosol generator 301 , a stop valve 302 , and a droplet beam device 303 which are connected in sequence, and the droplet beam device 303 is connected to the sample pool 102 .

[0076] For example, Figure 3 As shown, the droplet beam device 303 includes a plurality of pipelines with different inner diameters connected in sequence, and the inner diameters of the plurality of pipelines 3031 gradually decrease along the aerosol flow direction.

[0077] Furthermore, a plurality of apertures 3032 with different inner diameters are arranged inside the pipeline 3031, and the inner diameters of the plurality of apertures 3032 gradually decrease along the aerosol flow direction.

[0078] For example, Figure 4As shown, along the flow direction of the aerosol droplets, three apertures with gradually decreasing inner diameters are sequentially arranged in the first pipeline, an aperture with a smaller inner diameter than the inner diameter of the second pipeline is arranged at the outlet of the second pipeline, and an aperture with a smaller inner diameter than the inner diameter of the third pipeline is arranged at the outlet of the third pipeline. This embodiment can gradually arrange the gathered droplets into a string and discharge them from the outlet. Figure 5 shown.

[0079] For example, the inner diameter of the aperture at the outlet of the third pipeline is greater than or equal to the diameter of a single droplet and less than the diameter of the single droplet × 2. In other words, the aperture at the outlet of the third pipeline can only pass a single droplet at a time. Figure 5 shown.

[0080] Exemplarily, a gasket 3033 is provided between the aperture and the inner wall of the pipe.

[0081] Exemplarily, a clamp 3034 is provided at the inlet end of the first tube for fixing the tube and adjusting the tube so that it is aligned with the light capture point in the sample pool 102 .

[0082] Exemplarily, a threaded cap 3035 with a central hole is provided at the outlet of the third pipeline. The threaded cap 3035 is used to protect the outlet of the third pipeline.

[0083] Exemplarily, the humidity regulating gas circuit system 204 is connected to a pipeline between the stop valve 302 and the droplet beam device 303 .

[0084] Exemplarily, the optical coupling system 4 includes a laser 401, a focusing lens 402, a semi-transparent and semi-reflective mirror 403, and a total reflection mirror 404. The light beam emitted by the laser 401 is expanded by a group of focusing lenses 402, and then the single-beam optical tweezers split the light beam through the semi-transparent and semi-reflective mirror 403, and the light beam is respectively divided into the single-droplet optical tweezers suspension device 1, the light beam coupling system 4, and the signal detection system 5. The light beam divided into the single-droplet optical tweezers suspension device 1 is sent to the microscope objective 101, and the laser is focused above the focal plane to capture the single droplet in the sample pool 102 and suspend it. The scattered light signal of the single droplet is respectively input into the signal detection system 5 and the droplet detection device 6, and the light signal can be processed by the filter before entering the signal detection system 5.

[0085] Exemplarily, the signal detection system 5 includes an optical imaging camera 501, a Raman spectrometer 502, and a data processing unit 503. The spectral imaging of the droplet is performed on the optical imaging camera EMCCD 501 through the grating in the Raman spectrometer 502, and the spectral information and Raman spectrum of different pixel elements are obtained; based on the whispering gallery mode of the spherical droplet, the droplet radius is inverted according to the Mie scattering theory; the spontaneous and stimulated Raman spectra and resonance signals of the suspended single droplet are obtained through the optical imaging camera 501 and the Raman spectrometer 502; and the spectrum information is converted into radius, refractive index, and peak position information through the data processing unit 503. According to the measured red shift of the stimulated Raman peak of the droplet, the droplet radius change rate dr / dt can be obtained, and then the chemical composition and component changes of the droplet are analyzed, and the saturated vapor pressure is calculated.

[0086] Exemplarily, the droplet detection device 6 is a microscopic imaging camera. The microscopic imaging camera 6 is used to monitor the lateral macroscopic morphology of the droplet when it is suspended.

[0087] On the other hand, the present invention also provides a method for monitoring aerosol single droplets in a real atmosphere, using the above-mentioned aerosol single droplet monitoring device in a real atmosphere, the method comprising:

[0088] The droplet pumping system pumps the aerosol into the sample pool of the single droplet optical tweezers suspension device in the form of a single droplet;

[0089] The laser emitted by the beam coupling system is used as a trapping beam to capture a single droplet in the sample cell and suspend it using the optical tweezers technique;

[0090] One of the first gas path and the second gas path is used as an inlet gas path, and the other gas path is used as an outlet gas path, and real air is introduced into the sample cell through the inlet gas path, and the real air reacts with specific components in the single droplet when flowing through the sample cell;

[0091] The scattered light signal of a single droplet is input into the signal detection system and the droplet detection device respectively. The property changes of the single droplet during the reaction process in the real atmospheric atmosphere are monitored according to the light signal data, and the saturated vapor pressure is calculated according to the numerical change of the single droplet radius before and after the single droplet reaction.

[0092] Furthermore, the changes in the actual atmospheric composition before and after the reaction are monitored by gas composition analyzers on the first gas path and the second gas path.

[0093] Furthermore, the droplets are arranged into a string by the droplet beam device 303 of the droplet pumping system 3 to form an aerosol droplet beam, so that the aerosol droplets enter the sample pool 102 one by one as a monodisperse single string of droplets. This can effectively prevent the aggregated aerosol droplets from easily depositing on the wall of the sample pool after entering the sample pool at the same time, thereby generating a wall effect.

[0094] Furthermore, the method also includes: after suspending a single droplet through the optical tweezers technology, dry gas and / or wet gas is introduced into the sample pool 102 through the humidity regulating gas circuit system 204, the humidity in the sample pool 102 is reduced to below the weathering point humidity of the volatile chemical components in the droplet, and the droplets on the inner wall of the sample pool 102 are weathered and crystallized, and then the humidity regulating gas circuit system 204 is closed, and the real atmosphere is introduced into the sample pool 102. The humidity in the sample pool 102 will be adjusted up to the humidity of the real atmosphere as the real atmosphere is continuously introduced.

[0095] The present invention reduces the humidity to below the weathering point humidity, so that the droplets attached to the vessel wall are weathered and crystallized first compared to the droplets being tweezed. The solid after weathering and crystallization no longer has the curvature radius of the liquid phase, and the curvature radius of the droplet determines the surface pressure, which is also the key value on which the saturated vapor pressure of the droplet depends. Therefore, by reducing the humidity to first weather and crystallize the droplets on the vessel wall, the influence of the surface pressure and saturated vapor pressure is eliminated, and then the humidity is raised to the humidity of the real atmosphere, so as to accurately obtain the saturated vapor pressure value of the single droplet of the optical tweezers.

[0096] It should be noted that the reasons why the droplets attached to the vessel wall weather and crystallize before the droplets tweezed by the optical tweezers are: (1) The temperature of the vessel wall is usually lower than that of the center of the sample pool because the heat exchange between the vessel wall and the surrounding environment is more direct. This temperature difference makes it easier for the droplets on the vessel wall to reach the conditions for weathering and crystallization; (2) The optical tweezers technique can precisely control the position of a single droplet, keeping it in the center of the sample pool and away from the vessel wall, which reduces the chance of the central droplet contacting the vessel wall, while the droplets on the vessel wall are more easily affected by environmental conditions.

[0097] By reducing the humidity to below the weathering point, the droplets attached to the wall will weather and crystallize before the droplets being tweezed, thereby reducing the influence of the wall effect on the saturated vapor pressure of a single droplet. The principle is as follows: (1) When the humidity is reduced to below the weathering point, the droplets on the inner wall of the sample pool will begin to weather due to the decrease in ambient humidity, that is, the water in the droplets will gradually evaporate, resulting in an increase in the solute concentration in the droplets, eventually reaching a saturated state and beginning to crystallize. This process reduces the content of volatile organic components in the droplets; (2) Since volatile organic components are more likely to evaporate in a low humidity environment, these components will be removed during the weathering and crystallization process, thereby reducing their potential impact on subsequent experiments. At this time, the saturated vapor pressure of the solid-liquid mixture is determined by the adsorbed water molecules, rather than the original volatile organic components; (3) When the humidity in the sample pool is returned to the humidity of the real atmosphere, the crystals on the wall will adsorb water molecules in the environment to form a solid-liquid mixture. At this time, the liquid phase in the solid-liquid mixture is composed only of adsorbed water molecules and no longer contains the original volatile organic components; (4) The Kelvin effect shows that the smaller the radius of curvature, the greater its saturated vapor pressure.

[0098] In summary, the droplets attached to the bottom of the sample pool all reduce their radius of curvature to avoid the error of the saturated vapor pressure of the volatile components inside. The droplets on the inner wall are first dehumidified to below the weathering point of the volatile component droplets by first dehumidifying and then rehumidifying, so that the water molecules inside the droplets evaporate and the droplets become smaller and the radius of curvature increases, causing the droplets on the wall to weather and crystallize before the droplets on the optical tweezers; when the humidity rises, the saturated vapor pressure of the solid-liquid mixture is determined by the adsorbed water molecules, rather than the original volatile organic components.

[0099] Compared with the droplets on the inner wall, the droplets suspended by optical tweezers do not show weathering and crystallization for the following reasons: the single droplet suspended by optical tweezers always maintains a spherical shape and always has a radius of curvature. From the perspective of avoiding the vessel wall effect: (1) The optical tweezers technique can precisely control the position of the droplets, keeping them in the center of the sample pool. The temperature and humidity conditions in this area may be relatively stable and less susceptible to changes in the external environment. (2) The optical tweezers manipulate the droplets by focusing the radiation pressure generated by the laser beam. This manipulation method can isolate the direct heat exchange between the droplets and the vessel wall to a certain extent, reducing the drop in surface temperature and evaporation of the droplets caused by the cooling of the vessel wall. (3) The humidity in the vessel wall area decreases first, prompting the weathering and crystallization of the droplets on the vessel wall, while the humidity change in the central area is slower than that of the vessel wall, so the vessel wall first experiences weathering and crystallization. (4) The aerosol droplets suspended by the optical tweezers are already in a supersaturated state and have a small particle size. Their surface properties are different from those of the droplets deposited on the vessel wall. The differences in the surface and interface colloidal properties of the aerosol itself may also be the reason why the evaporation rate and weathering and crystallization of the vessel wall droplets take precedence over the optical tweezers droplets.

[0100] Illustratively, after a single droplet is suspended by optical tweezers technology, dry gas and / or wet gas is introduced into the sample pool 102 through the humidity regulating gas circuit system 204, and the humidity in the sample pool 102 is adjusted to 30%-40%. After the droplets on the inner wall of the sample pool 102 are weathered and crystallized, the humidity regulating gas circuit system 204 is closed to restore the humidity to the humidity of the real atmosphere.

[0101] Humidity can be adjusted by the mass flow ratio of dry gas and wet gas. For example, the dry gas reading range is 0.05-0.15SLPM and the wet gas reading range is 0.15-0.05SLPM. The humidity of dry and wet gas can be adjusted by adjusting the readings of dry gas and wet gas, that is, adjusting the ratio of dry gas and wet gas. The larger the dry gas / wet gas ratio, the lower the humidity; the smaller the dry gas / wet gas ratio, the higher the humidity.

[0102] Exemplarily, the method further includes: after the droplets enter the droplet beam device 303, closing the stop valve 302, and introducing nitrogen into the droplet beam device 303 through the humidity regulating gas path system 204 to dilute the droplets in the droplet beam device 303, thereby further promoting the droplet beam device 303 to change the droplets from an aggregated state into a monodisperse single string of droplets that enter the sample pool one by one.

[0103] It should be noted that after the light nickel captures and suspends the droplets, there is no need to dilute the droplets in the droplet beam device 303. At this time, the nitrogen gas path of the humidity regulating gas path system 204 is closed to prevent it from affecting the composition of the real atmosphere.

[0104] The aerosol single droplet monitoring device and method in a real atmospheric atmosphere of the present invention are further described below by way of specific embodiments.

[0105] Example 1

[0106] This embodiment provides an aerosol single droplet monitoring device under a real atmospheric atmosphere, comprising a single droplet optical tweezers suspension device 1, a gas circuit system 2, a droplet pumping system 3, a beam coupling system 4, a signal detection system 5 and a droplet detection device 6; wherein the gas circuit system 2 comprises a real atmospheric gas circuit system, the real atmospheric gas circuit system is connected to the single droplet optical tweezers suspension device 1, the droplet pumping system 3 is connected to the single droplet suspension system 1, the beam coupling system 4 is respectively connected to the single droplet optical tweezers suspension device 1, the signal detection system 5 and the droplet detection device 6; the real atmospheric gas circuit system comprises a first gas circuit 201 and a second gas circuit 202, the first gas circuit 201 and the second gas circuit 202 are respectively connected to the single droplet optical tweezers suspension device 1, a gas component analyzer 203 is arranged on the first gas circuit 201, and a gas component analyzer 203 and a pump gas device 2021 are arranged on the second gas circuit 202; the single droplet optical tweezers suspension device 1 comprises a sample pool 102, such as Figure 2 As shown, the sample pool 102 includes a concentric outer ring wall 1021 and an inner ring wall 1022, the outer ring wall 1021 is connected to one side of the inner ring wall 1022, and a single droplet inlet 1023 penetrating the outer ring wall 1021 and the inner ring wall 1022 is provided at the connection; the outer ring wall 1021 and the inner ring wall 1022 are provided with a plurality of gas inlets 1024 and gas outlets 1025 penetrating the ring wall and arranged at intervals, and the gas inlet 1024 and gas outlet 1025 on the outer ring wall 1021 are staggered with the gas inlet 1024 and gas outlet 1025 on the inner ring wall 1022; the diameter of the single droplet inlet 1023 is 3 mm, the diameter of the gas inlet 1024 is 1.0 mm, and the diameter of the gas outlet 1025 is 1.5 mm. The spacing between the outer ring wall 1021 and the inner ring wall 1022 is 2 mm.

[0107] The gas pumping device 2021 is a vacuum pump, and the first gas circuit 201 is also provided with a filter device 2011 and a temperature and humidity recorder 2012. The second gas circuit 202 is also provided with a mass flow meter 2022 and a flow valve 2023. The filter device 2011, the gas composition analyzer 203, and the temperature and humidity recorder 2012 on the first gas circuit 201 are sequentially arranged in a direction close to the single droplet optical tweezers suspension device 1, and the gas pumping device 2021, the flow valve 2023, the mass flow meter 2022, and the gas composition analyzer 203 on the second gas circuit 202 are sequentially arranged in a direction close to the single droplet optical tweezers suspension device 1.

[0108] The gas circuit system 2 further includes a humidity regulating gas circuit system 204, and the humidity regulating gas circuit system 204 is connected with the droplet pumping system 3. The humidity regulating gas circuit system 204 includes a gas generating device 2041 and a flow meter 2042.

[0109] A quartz glass sheet is disposed at the bottom of the sample pool 102 , and an anionic surfactant layer (sodium fatty alcohol ether sulfate) with a thickness of 0.2 mm is disposed on the quartz glass sheet.

[0110] The single-droplet optical tweezers suspension device 1 further includes a microscope objective lens 101 and an illumination light source 103 . The microscope objective lens 101 is disposed between the sample pool 102 and the beam coupling system, and the illumination light source 103 is disposed above the sample pool 102 .

[0111] The droplet pumping system 3 includes an aerosol generator 301, a stop valve 302 and a droplet beam device 303 which are connected in sequence, and the droplet beam device 303 is connected to the sample pool 102. The droplet beam device 303 includes three pipelines with different inner diameters which are connected in sequence, and the inner diameters of the three pipelines 3031 gradually decrease along the aerosol flow direction. A plurality of diaphragms 3032 with different inner diameters are arranged inside the pipeline 3031, and the inner diameters of the plurality of diaphragms 3032 gradually decrease along the aerosol flow direction. Three diaphragms with gradually decreasing inner diameters are arranged in sequence in the first pipeline, an diaphragm with an inner diameter smaller than that of the second pipeline is arranged at the outlet of the second pipeline, and an diaphragm with an inner diameter smaller than that of the third pipeline is arranged at the outlet of the third pipeline. The inner diameters of each pipeline and diaphragm are as follows: Figure 4 shown.

[0112] The humidity regulating gas circuit system 204 is connected to the pipeline between the stop valve 302 and the droplet beam device 303 .

[0113] The optical coupling system 4 includes a laser 401, a focusing lens 402, a semi-transparent mirror 403 and a total reflection mirror 404. The signal detection system 5 includes an optical imaging camera 501, a Raman spectrometer 502 and a data processing unit 503. The droplet detection device 6 is a microscopic imaging camera.

[0114] Example 2

[0115] This embodiment provides a method for monitoring aerosol single droplets in a real atmosphere, using the device of embodiment 1. It includes:

[0116] The aerosol generator 301 forms droplets from the aerosol, and the aerosol droplets enter the droplet beam device 303. After the droplets enter the droplet beam device 303, the stop valve 302 is closed, and nitrogen is introduced into the droplet beam device 303 through the humidity regulating gas path system 204 to dilute the droplets in the droplet beam device 303, so as to promote the droplet beam device 303 to arrange the droplets into a string to form an aerosol droplet beam, so that the aerosol droplets enter the sample pool 102 of the single droplet optical tweezers suspension device 1 one by one in the form of a monodispersed single string of droplets;

[0117] The light beam emitted by the laser 401 of the beam coupling system 4 is expanded by a group of focusing lenses 402, and then the single-beam optical tweezers split the beam through a semi-transparent and semi-reflective mirror 403, and a part of the light beam is split to the microscope objective 101, and the laser is focused above the focal plane to capture a single droplet in the sample pool 102 (the droplet is an ammonium sulfate droplet containing 0.01wt% Cu, and the ammonium sulfate is non-volatile) and suspend it; the nitrogen source of the humidity regulating gas circuit system 204 is turned off;

[0118] The first gas path 201 is used as an inlet gas path, and the second gas path 202 is used as an outlet gas path. Real air (real air from Liangxiang, Beijing) is introduced into the sample pool 102 through the first gas path 201;

[0119] When the real atmosphere flows through the sample pool 102, it reacts with the specific components in the single droplet, and the changes in the real atmosphere components before and after the reaction are monitored by the gas component analyzers 203 on the first gas path 201 and the second gas path 202;

[0120] The returned single droplet scattered light signal is input into the signal detection system 5 and the droplet detection device 6 through a focusing lens 402 and a total reflection mirror 404 respectively. The property changes of the single droplet in the reaction process under the real atmospheric atmosphere are monitored according to the light signal data, and the saturated vapor pressure is calculated according to the numerical change of the single droplet radius before and after the single droplet reaction.

[0121] Figure 6 The change trend of droplet size over time in the real atmosphere background and the recorded humidity change of Example 2; Figure 7The PM monitored by Beijing Liangxiang Monitoring Station at the corresponding time of Example 2 2.5 、PM 10 , SO2, NO2 and O3 concentration changes.

[0122] from Figure 6 It can be seen that within the monitoring time range, the relative humidity of the real atmosphere changed little, while the droplet radius showed an overall increasing trend, and the droplet radius increased relatively quickly from 18:00 on December 16 to 12:00 on December 17. The reasons may be: ammonium sulfate is not volatile, and from 18:00 on December 16 to 12:00 on December 17, ammonium sulfate reacted chemically with components in the real atmosphere, increasing the components in the droplets and gradually increasing the droplet radius; after 12:00 on December 17, the chemical reaction tended to equilibrium and the droplet radius no longer increased.

[0123] from Figure 7 It can be seen that PM in the real atmosphere 2.5 、PM 10 The concentration changes of SO2, NO2 and O3 during the monitoring period showed that PM 2.5 、PM 10 The concentrations of NO2 and SO2 showed an upward trend, while the concentration of O3 showed a downward, upward and then downward trend. The concentration of NO2 showed an overall upward trend, and the concentration of SO2 changed relatively little. Under the condition that copper ions existed in the droplets, the copper ion catalyzed NO2 oxidation of S(IV) to generate S(VI) was a more important S(VI) generation pathway than the O3 oxidation pathway. Figure 6 The variation trend of droplet radius and Figure 7 The change trend of NO2 concentration in the study area is relatively consistent, which also confirms this view to a certain extent.

[0124] Example 3

[0125] This embodiment provides a method for monitoring aerosol single droplets in a real atmospheric atmosphere similar to that of Embodiment 2, except that the main component in the single droplet is ammonium chloride (which is volatile). After the optical tweezers capture and suspend the droplet, a ratio of dry gas and / or wet gas is introduced into the sample pool 102 through the humidity regulating gas circuit system 204, and the humidity in the sample pool 102 is adjusted to 30% (the humidity at the weathering point of ammonium chloride is 40%). After the droplets on the inner wall of the sample pool 102 are weathered and crystallized, the humidity regulating gas circuit system 204 is closed, and real gas is introduced into the sample pool 102 to adjust the humidity to the humidity of the real atmosphere (about 62%).

[0126] Under stable RH (relative humidity) conditions, the typical measurement accuracy of the droplet radius is ±0.57nm (expressed as the standard deviation of 30 seconds of data acquisition) and the refractive index is ±0.00027. Therefore, when the ambient RH fluctuates greatly, the actual change in the microenvironment around the droplet is much smaller than the noise effect of the RH measurement. The local stability of the droplet in the optical tweezers is high and the local humidity field around the droplet is relatively constant. The droplet composition remains unchanged before the reaction and the RH is fixed. As the reaction proceeds, the continuous reduction in the droplet radius will be entirely attributed to the volatilization of the components and water in the droplet.

[0127] The saturated vapor pressure of the components inside a single droplet is measured in real time. The mass flux of the volatile components is obtained based on the changes in the droplet radius and the droplet mass, and the average saturated vapor pressure is calculated (for specific calculation methods, see Phys. Chem. Chem. Phys., 2014, 16, 3162 DOI: 10.1039 / c3cp54948h; J. Phys. Chem. A 2015, 119, 704-718 DOI: 10.1021 / jp510525r).

[0128] According to calculations, the average saturated vapor pressure of a single droplet in the real atmosphere is 1.58×10 -5 pa.

[0129] Example 4

[0130] This embodiment provides a method for monitoring aerosol single droplets in a real atmospheric atmosphere similar to that of Embodiment 3, except that no anionic surfactant layer is coated on the quartz glass sheet at the bottom of the sample cell.

[0131] In this example, the average saturated vapor pressure of a single droplet in the real atmosphere is 5.82×10 -5 pa.

[0132] Example 5

[0133] This embodiment provides an aerosol single droplet monitoring method in a real atmospheric atmosphere similar to that of Embodiment 3, except that no droplet beam device 303 is provided in the droplet pumping system 3 .

[0134] In this example, the average saturated vapor pressure of a single droplet in the real atmosphere is 5.78×10 -5 pa.

[0135] Example 6

[0136] This embodiment provides a method for monitoring aerosol single droplets in a real atmospheric atmosphere similar to that of Embodiment 3, except that the droplets in the droplet beam device 303 are not diluted by closing the stop valve 302 and passing nitrogen gas.

[0137] In this example, the average saturated vapor pressure of a single droplet in the real atmosphere is 5.69×10 -5 pa.

[0138] Example 7

[0139] This embodiment provides a method for monitoring aerosol single droplets in a real atmospheric atmosphere similar to that of Embodiment 3, except that after the optical tweezers suspend the single droplet, the humidity is not lowered to below the weathering point humidity of the droplet components, and the droplet changes in the real atmospheric atmosphere are directly detected.

[0140] In this example, the average saturated vapor pressure of a single droplet in the real atmosphere is 6.64×10 -5 pa.

[0141] Comparative Example 1

[0142] An existing aerosol single droplet monitoring device method under real atmospheric atmosphere is adopted. The device is similar to the device of Example 1, except that the sample cell is single-walled; the diameters of the single droplet inlet and the gas outlet are equal, and the bottom of the sample cell is not coated with anionic surfactant; no stop valve and droplet beam device are set in the droplet pumping system; when the device is used to detect the saturated vapor pressure of aerosol single droplets, the method is similar to the method of Example 3, except that after the optical tweezers suspend the single droplet, the monitoring is directly carried out under the humidity of the real atmospheric atmosphere.

[0143] In this comparative example, the average saturated vapor pressure of a single droplet in the real atmosphere is 9.87×10 -5 pa.

[0144] It can be seen from the average saturated vapor pressure detection data of Examples 2-7 and Comparative Example 1 that the saturated vapor pressure data obtained by using the device and method of the present invention are smaller than the data of Comparative Example 1. This is because the present invention reduces the error effect on the saturated vapor pressure caused by the organic volatile components in the droplets deposited on the wall and the bottom of the sample pool. Therefore, the saturated vapor pressure measured by the present invention is closer to the true saturated vapor pressure value, that is, the saturated vapor pressure value measured by the present invention has a smaller error.

[0145] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An aerosol single droplet monitoring device in a real atmospheric atmosphere, characterized in that: The device comprises a single droplet optical tweezers suspension device, an air path system, a droplet pumping system, a beam coupling system, a signal detection system and a droplet detection device; Wherein, the gas circuit system includes a real atmospheric gas circuit system, the real atmospheric gas circuit system is connected to the single droplet optical tweezers suspension device, the droplet pumping system is connected to the single droplet suspension system, and the beam coupling system is respectively connected to the single droplet optical tweezers suspension device, the signal detection system and the droplet detection device; The real atmosphere gas path system comprises a first gas path and a second gas path, the first gas path and the second gas path are both connected to the real atmosphere, the first gas path and the second gas path are respectively connected to the single droplet optical tweezers suspension device, and a pumping device is arranged on the second gas path, and the pumping device is a vacuum pump or an air compressor; The single droplet optical tweezers suspension device comprises a sample pool, which comprises a concentric outer ring wall and an inner ring wall, wherein the outer ring wall is connected to one side of the inner ring wall, and a single droplet inlet penetrating the outer ring wall and the inner ring wall is arranged at the connection; the outer ring wall and the inner ring wall are both provided with a plurality of gas inlets and gas outlets penetrating the ring walls and arranged at intervals, and the gas inlet and gas outlet on the outer ring wall are staggered with the gas inlet and gas outlet on the inner ring wall; The diameter of the gas inlet and the diameter of the gas outlet are both smaller than the diameter of the single droplet inlet.

2. The device according to claim 1, characterized in that The first gas path is also provided with a filtering device.

3. The device according to claim 1, characterized in that Gas composition analyzers are provided on both the first gas path and the second gas path.

4. The device according to claim 1, characterized in that A temperature and humidity recorder is also provided on the first gas path.

5. The device according to claim 1, characterized in that The second gas path is also provided with a mass flow meter and a flow valve.

6. The device according to claim 1, characterized in that The gas circuit system further comprises a humidity regulating gas circuit system, and the humidity regulating gas circuit system is communicated with the droplet pumping system.

7. The device according to claim 1, characterized in that The distance between the outer annular wall and the inner annular wall is 2-3 mm.

8. The device according to claim 1, characterized in that A quartz glass sheet is arranged at the bottom of the sample pool, and an anionic surfactant layer is arranged on the quartz glass sheet.

9. The device according to claim 1, characterized in that The thickness of the anionic surfactant layer is 0.1-0.2 mm.

10. A method for monitoring aerosol single droplets in a real atmosphere, characterized in that: Using the aerosol single droplet monitoring device in a real atmospheric atmosphere as described in any one of claims 1 to 9, the method comprises: The droplet pumping system pumps the aerosol into the sample pool of the single droplet optical tweezers suspension device in the form of a single droplet; The laser emitted by the beam coupling system is used as a trapping beam to capture a single droplet in the sample cell and suspend it using the optical tweezers technique; One of the first gas path and the second gas path is used as an inlet gas path, and the other gas path is used as an outlet gas path, and real air is introduced into the sample cell through the inlet gas path, and the real air reacts with specific components in the single droplet when flowing through the sample cell; The scattered light signal of a single droplet is input into the signal detection system and the droplet detection device respectively. The property changes of the single droplet during the reaction process in the real atmospheric atmosphere are monitored according to the light signal data, and the saturated vapor pressure is calculated according to the numerical change of the single droplet radius before and after the single droplet reaction.

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