CN116380872A - Laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device - Google Patents
Laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device Download PDFInfo
- Publication number
- CN116380872A CN116380872A CN202211695401.4A CN202211695401A CN116380872A CN 116380872 A CN116380872 A CN 116380872A CN 202211695401 A CN202211695401 A CN 202211695401A CN 116380872 A CN116380872 A CN 116380872A
- Authority
- CN
- China
- Prior art keywords
- aerosol
- laser
- unit
- photomultiplier
- particle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000443 aerosol Substances 0.000 title claims abstract description 131
- 239000002245 particle Substances 0.000 title claims abstract description 86
- 238000001514 detection method Methods 0.000 title claims abstract description 45
- 238000002536 laser-induced breakdown spectroscopy Methods 0.000 title claims abstract description 34
- 238000004458 analytical method Methods 0.000 claims abstract description 27
- 238000001228 spectrum Methods 0.000 claims abstract description 25
- 230000005284 excitation Effects 0.000 claims abstract description 24
- 238000002347 injection Methods 0.000 claims abstract description 19
- 239000007924 injection Substances 0.000 claims abstract description 19
- 230000003287 optical effect Effects 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 10
- 230000008569 process Effects 0.000 claims abstract description 5
- 238000012360 testing method Methods 0.000 claims abstract description 4
- 230000015556 catabolic process Effects 0.000 claims abstract 2
- 230000003595 spectral effect Effects 0.000 claims description 17
- 230000005540 biological transmission Effects 0.000 claims description 9
- 238000005070 sampling Methods 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- 210000002381 plasma Anatomy 0.000 abstract description 18
- 238000000608 laser ablation Methods 0.000 abstract 1
- 239000000126 substance Substances 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 6
- 238000011160 research Methods 0.000 description 4
- 230000035945 sensitivity Effects 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000002834 transmittance Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 239000013307 optical fiber Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 101000694017 Homo sapiens Sodium channel protein type 5 subunit alpha Proteins 0.000 description 1
- 102100027198 Sodium channel protein type 5 subunit alpha Human genes 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000012491 analyte Substances 0.000 description 1
- 238000000559 atomic spectroscopy Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 230000003203 everyday effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000004255 ion exchange chromatography Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000001819 mass spectrum Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000013618 particulate matter Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
- G01N21/718—Laser microanalysis, i.e. with formation of sample plasma
Landscapes
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Abstract
The invention provides a laser-induced breakdown spectrum aerosol single-particle high-sensitivity detection device, which belongs to the field of aerosol detection, and comprises an aerosol sample injection unit, a laser excitation unit, a spectrum acquisition unit and a control unit, wherein: the aerosol sample injection unit collects aerosol and forms aerosol single-particle beam, and plasma is generated under the pulse laser ablation generated by the laser excitation unit; the spectrum acquisition unit is used for colleting and collimating and splitting the optical signals radiated by the plasmas in universities, and the first acquisition assembly and the second acquisition assembly are used for efficiently acquiring the optical signals; the control unit is connected with the laser excitation unit and the spectrum acquisition unit and is used for controlling the testing process and collecting electric signals for analysis so as to obtain the types and the contents of elements to be detected in the aerosol single particles, and further realize the online detection of the aerosol single particles. The invention greatly improves the capability of LIBS for detecting weak light signals and realizes the high-sensitivity detection of LIBS aerosol single particles.
Description
Technical Field
The invention belongs to the field of aerosol detection, and particularly relates to a laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device.
Background
Aerosol refers to a gaseous dispersion system of solid or liquid particles suspended in a gaseous medium. Aerosols are widely visible in everyday life and their sources can be divided into two categories: natural sources and artificial sources. In recent years, PM2.5, which has been of great interest, is particulate matter having an aerodynamic diameter of 2.5 microns or less. With the attention of people on aerosols, more and more research reports indicate that the hazard of aerosol particulate pollution is far beyond the original expectation of people, and the production and the life of people are directly and indirectly influenced. Therefore, the development of reliable aerosol analysis techniques is of great significance.
Existing aerosol analysis techniques can be divided into two categories: offline analysis and online analysis. Off-line analysis is to separate aerosol particles from the atmosphere to make a sample, which is then taken to a laboratory for chemical analysis. The off-line analysis technology has high analysis precision and mature technology, but in the sampling process, the physical or chemical properties of the sample change, so that the measurement result cannot reflect the initial characteristics of the particles, and accurate measurement cannot be realized. The online analysis has the advantages of in situ, no need of sample pretreatment and the like, and the result directly reflects the intrinsic properties of particles, so the real-time online analysis is a future development prospect of aerosol analysis technology. The existing aerosol online analysis technology (such as an organic carbon element online analyzer, online ion chromatography, aerosol flight time mass spectrum and the like) has the problems of low precision, limited analysis elements and the like, and is difficult to meet the requirements of complex detection scenes. Therefore, there is a need for an aerosol online analysis technique that is highly accurate, rapid, and full elemental analysis. A laser-induced breakdown spectroscopy (LIBS) technology is a chemical analysis technology capable of realizing rapid element detection, and the principle is that a beam of high-energy pulse laser is focused on the surface of a sample to excite plasma, and the element type and content of the sample are deduced according to the wavelength and intensity of plasma radiation. LIBS can be used for fast detection of aerosol on site due to the characteristics of no need of sample preparation, fast, in situ, full element analysis and the like.
The LIBS aerosol detection is divided into two categories by the academy: aerosol population analysis and single particle analysis. The group analysis refers to that more than one particle exists in a plasma sampling area, the average chemical composition of all particles in the plasma is researched, but the characteristics of target particles are easily covered by high-concentration background particles, and the chemical property differences among the particles cannot be distinguished. In contrast, single particle analysis has particle-scale resolution, with only one aerosol particle analysis at a time. However, in LIBS aerosol single particle detection, the mass of substances contained in aerosol single particles is small, the emission intensity of element characteristic spectral lines is low, and the detection limit of a conventional LIBS method cannot meet the single particle detection requirement, so that the detection result cannot reflect the actual situation.
Aiming at the problem that the traditional LIBS can not acquire an aerosol single-particle effective spectrum signal, a learner can acquire a higher signal-to-noise ratio by using an orthogonal double-pulse structure, so that the spectrum signal is enhanced, the single-particle sampling rate (Window B C, diwakar P K, hahn D W.Dual-pulse Laser Induced Breakdown Spectroscopy for analysis of gaseous and aerosol systems: plasma-analyte interactions [ J ]. Spectrochimica Acta Part B Atomic Spectroscopy,2006,61 (7): 788-796) is also improved, however, the method needs to use two pulse lasers, extra instruments are added, the device is complex, the system is huge, the device cost is higher, and meanwhile, the laser pulse delay between the two lasers needs to be optimized, so that the experimental difficulty is increased; furthermore, researchers have proposed that the spatial position of the particles in the plasma and the acquisition space size of the detection system have an impact on the acquisition efficiency (Lithgow G a, buckley S G. Effects of focal volume and spatial inhomogeneity on uncertainty in single-aerosol laser-induced breakdown spectroscopy measurements J Applied Physics Letters,2005,87 (1): 01501-3.) the authors believe that the paraxial acquisition is stronger but more fluctuating than the coaxial acquisition signal because the region where the paraxial structure acquires the plasma is smaller than the coaxial, the probability of particles appearing in this region is lower and therefore the fluctuation is greater, but at the same time as long as particles appear in this region, as many spectral lines emitted by the particles as possible are collected and the signal is stronger. In general, from the perspective of LIBS excitation and collection, a great deal of research has been conducted by students on how to obtain the effective spectrum signal of the single particle aerosol, but optimization of the collection system is rarely reported.
In summary, in the existing LIBS aerosol single particle detection, a unified, effective and low-cost solution has not been obtained for the problem of low luminous intensity caused by low single particle substance content. Most researches try to solve the problem of low luminous intensity of single particles of aerosol from the laser excitation point of view, but researches start from the point of view of optimizing an acquisition device. The acquisition device for common LIBS aerosol detection mainly comprises an acquisition lens, an optical fiber, a spectrometer and a detector. However, when this conventional device is applied to the single particle detection field, a problem that the signal is difficult to detect often occurs. The main reasons for this can be categorized into two categories: on the one hand, due to the limitations of lens size, optical fiber numerical aperture and spectrometer F-number, the collection system has lower light receiving efficiency, which results in weaker optical signals transmitted to the detector surface; on the other hand, the sensitivity of the detector is low and is not suitable for detecting weak signals. There are also scholars using enhanced charge coupled devices (ICCDs) as detectors to improve the detection capabilities of LIBS detection systems, but their high cost is not conducive to the popularization of LIBS in application scenarios. Therefore, developing a set of highly sensitive collection devices would help to improve the problem of difficulty in detecting signals from single LIBS aerosol particles.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device, and aims to solve the problems that the existing detection device is low in sensitivity and difficult to detect signals.
In order to achieve the above purpose, the invention provides a laser-induced breakdown spectroscopy aerosol single particle high-sensitivity detection device, which comprises an aerosol sample injection unit, a laser excitation unit, a spectrum acquisition unit and a control unit, wherein:
the aerosol sample injection unit is arranged perpendicular to the laser excitation unit and is used for collecting aerosol and forming aerosol single-particle beam;
the laser excitation unit is used for generating pulse laser so as to ablate aerosol single-particle beam generated by the aerosol sample injection unit and generate plasma;
the spectrum acquisition unit comprises a parabolic mirror, a dichroic mirror, a first acquisition component and a second acquisition component, wherein the parabolic mirror is arranged at the intersection position of the aerosol sample injection unit and the laser excitation unit and is used for collimating light rays emitted by plasma; the dichroic mirror is arranged in the propagation direction of the collimated light, and the mirror surface of the dichroic mirror forms an included angle of 45 degrees with the collimated light and is used for separating characteristic spectral lines of elements to be detected in the collimated light so as to divide the collimated light into reflected light and transmitted light and respectively send the reflected light and the transmitted light into the first acquisition assembly and the second acquisition assembly; the first acquisition component comprises a first narrowband optical filter, a first focusing lens and a first photomultiplier which are sequentially arranged along the transmission direction of reflected light and is used for transmitting a light beam of a characteristic spectral line of a certain element to be detected and converting the light beam into an electric signal; the second acquisition component comprises a second narrowband optical filter, a second focusing lens and a second photomultiplier which are sequentially arranged along the transmission light propagation direction and is used for transmitting a light beam of a characteristic spectral line of another element to be detected and converting the light beam into an electric signal;
the control unit is connected with the laser excitation unit and the spectrum acquisition unit and is used for controlling the testing process and collecting electric signals for analysis so as to obtain the types and the contents of elements to be detected in the aerosol single particles, and further realize the online detection of the aerosol single particles.
As a further preferred feature, the aerosol sample introduction unit comprises an aerosol collector, an aerosol delivery element, a pneumatic connection element, a capillary tube and a suction pump, wherein: the aerosol collector is connected with the capillary tube through the aerosol conveying element and the pneumatic connecting element in sequence so as to collect aerosol in air and convey the aerosol into the capillary tube; the capillary tube is inserted into the parabolic mirror from the upper part and is used for forming aerosol single-particle beam; the suction pump is inserted into the interior of the parabolic mirror from the lower portion for recovering exhaust gas.
As a further preferred feature, the laser excitation unit comprises a pulse laser and a laser focusing lens connected in sequence along the laser propagation direction, the pulse laser is used for emitting pulse laser, the optical axis of the laser focusing lens is collinear with the pulse laser, and the laser focusing lens is used for focusing the pulse laser on the aerosol single particle beam to ablate the aerosol single particle beam and generate plasma.
As a further preferred aspect, the control power supply includes a timing generator, a data acquisition card and a computer, where the timing generator is respectively connected to the pulse laser, the first photomultiplier, the second photomultiplier and the data acquisition card to trigger the operation thereof; the data acquisition card is connected with the first photomultiplier and the second photomultiplier and is used for collecting the electric signals output by the data acquisition card; the computer is connected with the data acquisition card to read and analyze the electric signals, so as to obtain the types and the contents of the elements to be detected in the aerosol single particles.
As a further preferred aspect, the laser focusing lens is an aspherical plano-convex lens coated with a laser antireflection film.
As a further preferred aspect, the parabolic mirror is a parabolic mirror coated with an ultraviolet-enhanced aluminum film.
As a further preferred aspect, the dichroic mirror is a long-pass dichroic mirror, and the operating wavelength range is in the ultraviolet to near-infrared band.
As a further preferred aspect, the first narrowband filter and the second narrowband filter are filters with a narrow half-width and are mounted in a filter wheel to realize switching of the narrowband filters.
In general, the above technical solutions conceived by the present invention have the following compared with the prior art
The beneficial effects are that:
1. the laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device provided by the invention efficiently collects and collimates light rays emitted by plasma into parallel light through the parabolic mirror, separates characteristic spectral lines of elements to be detected through dichroic mirror light splitting and a narrow-band filter, and finally efficiently collects light signals by a photomultiplier tube with high sensitivity to reflect the properties of particle aerosols and the differences of chemical properties among particles, wherein a reflective optical system can obtain a larger collection angle compared with a transmission optical system, the photomultiplier tube is a single-point detector, has no limitation of collection angle and large photosurface, can receive light energy to a greater extent, and has higher sensitivity, so that the capability of LIBS for detecting weak light signals is greatly improved, and the LIBS aerosol particle high-sensitivity detection is realized;
2. meanwhile, the structure of the aerosol sample injection unit is optimized, stable aerosol single-particle beam is generated by utilizing the capillary tube, abnormal fluctuation of detection signals can be obviously weakened, the stability of the monitoring device is obviously improved, and the device has the advantage of simple structure compared with a complex sheath gas device;
3. in addition, the invention optimizes the control unit, sets the time interval between the time of the pulse laser emitted by the pulse laser and the time of the spectrum collected by the first photomultiplier and the second photomultiplier and the collecting gate width by utilizing the time sequence generator, and collects analysis data in real time by the data collecting card and the computer so as to realize the real-time online detection of the aerosol single particles
Drawings
FIG. 1 is a schematic diagram of a laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device provided by an embodiment of the invention;
the same reference numbers are used throughout the drawings to reference like elements or structures, wherein:
the device comprises a 1-laser excitation unit, a 2-time sequence generator, a 3-pulse laser, a 4-computer, a 5-laser focusing lens, a 6-aerosol collector, a 7-aerosol sample injection unit, an 8-parabolic mirror, a 9-air pump, a 10-aerosol transport element, an 11-pneumatic switching element, a 12-capillary tube, a 13-spectrum acquisition unit, a 14-first photomultiplier, a 15-first focusing lens, a 16-first narrow-band filter, a 17-dichroic mirror, a 18-second focusing lens, a 19-second narrow-band filter, a 20-data acquisition card, a 21-second photomultiplier and a 22-control unit.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1, the invention provides a laser-induced breakdown spectroscopy aerosol single particle high-sensitivity detection device, which comprises an aerosol sample injection unit 7, a laser excitation unit 1, a spectrum acquisition unit 13 and a control unit 22, wherein:
the aerosol sample injection unit 7 is arranged perpendicular to the laser excitation unit 1, and the aerosol sample injection unit 7 is used for sampling aerosol in the atmospheric environment in real time and forming aerosol single-particle beam;
the laser excitation unit 1 is used for generating pulse laser so as to ablate aerosol single-particle beam generated by the aerosol sample injection unit 7 and generate plasma, and comprises a pulse laser 3 and a laser focusing lens 5 which are sequentially connected along the laser propagation direction, wherein the pulse laser 3 is used for emitting pulse laser, the optical axis of the laser focusing lens 5 is collinear with the pulse laser, the center of the pulse laser beam coincides with the mirror center of the laser focusing lens 5, and the laser excitation unit is used for focusing high-energy pulse laser emitted by the pulse laser 3 on the aerosol single-particle beam so as to ablate the aerosol single-particle beam and generate plasma;
the spectrum acquisition unit 13 comprises a parabolic mirror 8, a dichroic mirror 17, a first acquisition component and a second acquisition component, wherein the parabolic mirror 8 is arranged at the position where the aerosol sample injection unit 7 and the laser excitation unit 1 meet and is used for collimating light emitted by plasma, the focus of the parabolic mirror 8 coincides with the center of the plasma excited by the pulse laser 3, the surface of the parabolic mirror is provided with a through hole, and the central axis of the through hole passes through the focus of the parabolic mirror 8 and is orthogonal to the optical axis of the parabolic mirror 8; the dichroic mirror 17 is arranged in the propagation direction of the collimated light, the mirror surface of the dichroic mirror 17 forms an included angle of 45 degrees with the collimated light, the dichroic mirror is used for separating characteristic spectral lines of elements to be detected in the collimated light, the light beams with the wavelength are reflected by the dichroic mirror 17 to form reflected light, the reflected light propagates along the direction forming an included angle of 90 degrees with the incident direction and is sent into the first acquisition component, and the light beams with long wavelength penetrate through the dichroic mirror 17 to form transmitted light and are sent into the second acquisition component; the first collecting assembly comprises a first narrow-band filter 16, a first focusing lens 15 and a first photomultiplier 14 which are sequentially arranged along the transmission direction of reflected light, and is used for transmitting a beam of a characteristic spectral line of a certain element to be detected and converting the beam into an electric signal, the surface of the first narrow-band filter 16 is perpendicular to a short-wavelength beam reflected by a dichroic mirror 17, the optical axis of the first narrow-band filter is coincident with the central axis of the short-wavelength beam reflected by the dichroic mirror 17, the transmission wavelength of the first narrow-band filter is in a short-wavelength range, and the first narrow-band filter is used for transmitting the beam of the characteristic spectral line of the specific element; the optical axis of the first focusing lens 15 coincides with the optical axis of the first narrowband filter 16, and is used for focusing the reflected light transmitted by the first narrowband filter 16, the first photomultiplier 14 is positioned behind the first focusing lens 15, the photosurface of the first photomultiplier is opposite to the focused light beam, and the center of the photosurface of the first photomultiplier is aligned with the center of the focused light beam, and is used for collecting the light beam focused by the first focusing lens 15; the second collecting assembly comprises a second narrow-band filter 19, a second focusing lens 18 and a second photomultiplier 21 which are sequentially arranged along the transmission light propagation direction and are used for transmitting light beams of characteristic spectral lines of another element to be detected and converting the light beams into electric signals, the surface of the second narrow-band filter 19 is perpendicular to the light beams with long wavelengths transmitted through the dichroic mirror 17, the optical axis of the second narrow-band filter is coincident with the central axis of the long-wavelength light beams transmitted through the dichroic mirror 17, the transmission wavelength of the second narrow-band filter is in a long wavelength range and is used for transmitting the light beams of the characteristic spectral lines of the other element to be detected, and the optical axis of the second focusing lens 18 is coincident with the optical axis of the second narrow-band filter 19 and is used for focusing the collimated light beams transmitted by the second narrow-band filter 19; the second photomultiplier tube 21 is located behind the second focusing lens 18, and has a photosurface opposite to the focused light beam, and a photosurface center aligned with the focused light beam center for collecting the light beam focused by the second focusing lens 18;
the control unit 22 is connected with the laser excitation unit 1 and the spectrum acquisition unit 13, and is used for controlling the testing process and collecting electric signals for analysis so as to obtain the types and the contents of elements to be detected in the aerosol single particles, thereby realizing the online detection of the aerosol single particles.
Further, the aerosol feed unit 7 comprises an aerosol collector 6, an aerosol delivery element 10, a pneumatic connection element 11, a capillary tube 12 and a suction pump 9, wherein: the aerosol collector 6 is connected with the capillary 12 through the aerosol delivery element 10 and the pneumatic connecting element 11 in sequence to collect the aerosol in the air and deliver the aerosol into the capillary 12; the capillary tube 12 is inserted into the inside of the parabolic mirror 8 from the upper part through the through hole for forming aerosol single particle beam; the suction pump 9 is inserted into the interior of the parabolic mirror 8 from the lower portion through the through-hole for recovering the exhaust gas.
Further, the control power supply 22 comprises a time sequence generator 2, a data acquisition card 20 and a computer 4, wherein the time sequence generator 2 is respectively connected with the pulse laser 3, the first photomultiplier 14, the second photomultiplier 21 and the data acquisition card 20 to trigger the operation of the time sequence generator, and concretely comprises the steps of triggering the pulse laser 3 to generate high-energy pulses, triggering the first photomultiplier 14 and the second photomultiplier 21 to acquire spectrums, controlling the time interval between the output laser time of the pulse laser 3 and the acquisition spectrum time of the first photomultiplier 14 and the second photomultiplier 21, and controlling the acquisition gate widths of the first photomultiplier 14 and the second photomultiplier 21; the data acquisition card 20 is connected with the first photomultiplier 14 and the second photomultiplier 21 and is used for collecting the electric signals output by hands; the computer 4 is connected with the data acquisition card 20 to read and analyze the electric signals, and the types and the contents of the elements to be detected in the aerosol single particles are obtained through the intensity information of the characteristic spectral lines.
Further, the pulse laser is a high-energy Nd-YAG nanosecond pulse Q-switched laser; the laser focusing lens 5 is an aspheric plano-convex lens plated with a laser antireflection film; the parabolic mirror 8 is a parabolic mirror plated with an ultraviolet enhancement aluminum film; the dichroic mirror 17 is a long-wavelength-pass dichroic mirror, and the operating wavelength range is ultraviolet to near-infrared band; the first narrowband filter 16 and the second narrowband filter 19 are narrow half-width filters and are mounted in a filter wheel to effect switching of the narrowband filters.
Before the laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device provided by the invention is utilized, whether an aerosol sample injection unit 7 is damaged or not is checked, and whether an aerosol particle beam is a single-particle beam or not is checked; whether the pulse laser 3, the first photomultiplier 14, the second photomultiplier 21, the timing generator 2, the data acquisition card 20 and the computer 4 work normally or not; the laser focusing lens 5, the parabolic mirror 8, the dichroic mirror 17, the first narrow-band filter 16, the second narrow-band filter 19, the first focusing lens 15 and the second focusing lens 18 are intact and undamaged.
The detection method comprises the following steps: firstly, starting an aerosol sample injection unit 7, continuously sampling aerosol particles from the atmosphere, and transmitting the aerosol particles through a capillary 12 to form aerosol single-particle beam; setting a time interval between the time when the pulse laser 3 outputs laser and the time when the first photomultiplier and the second photomultiplier collect spectrum through the time sequence generator 2, and controlling the collection gate widths of the first photomultiplier 14 and the second photomultiplier 21; immediately turning on the pulse laser 3, the time sequence generator 2 transmits a high-level signal to the pulse laser 3, then the pulse laser 3 outputs laser, the high-energy laser beam generated by the pulse laser 3 is focused on aerosol single-particle beam flow through the laser focusing lens 5, aerosol particles are ablated, plasmas are generated, and light radiated by the plasmas is collimated, split and filtered by the spectrum acquisition unit 13 and then irradiated to the photosurfaces of the first photomultiplier 14 and the second photomultiplier 21; the time schedule controller 2 triggers the first photomultiplier 14 and the second photomultiplier 21 to collect optical signals after fixed time; then the data acquisition card 20 samples the electric signals output by the first photomultiplier 14 and the second photomultiplier 21 and outputs the electric signals to the computer 4; finally, the computer 4 receives and stores the signals output by the data acquisition card 20, analyzes the signals into spectrum data, and analyzes the spectrum data to obtain the types and the contents of the elements contained in the aerosol single particles.
In the preferred embodiment of the invention, the focal length of the parabolic mirror 8 is 2.45mm, the left side is provided with 8mm, the right side is provided with 37.5mm, and the inner wall is plated with an ultraviolet enhancement aluminum film; the dichroic mirror 17 is a long-wave-pass dichroic mirror, which has high reflectivity in a short-wave region and high transmittance in a long-wave region; the passband wave band of the first narrowband filter 16 is positioned in the short wave zone of the dichroic mirror, the bandwidth is smaller than 1nm, the transmittance in the bandwidth is 90%, the bandwidth comprises the wavelength corresponding to the characteristic spectral line of a certain element to be detected contained in the sample to be detected, and the diameter is 25.4mm; the passband wave band of the second narrowband filter 19 is positioned in the long wave area of the dichroic mirror 17, the bandwidth is smaller than 1nm, the transmittance in the bandwidth is 90%, the bandwidth contains the wavelength corresponding to the characteristic spectral line of another element to be detected contained in the sample to be detected, and the diameter is 25.4mm; the first focusing lens 15 is a plano-convex lens plated with an ultraviolet antireflection film, the diameter is 25.4mm, and the focal length is 50mm; the second focusing lens 18 is a plano-convex lens plated with an infrared antireflection film, the diameter is 25.4mm, and the focal length is 50mm; the diameter of the photosensitive surface of the first photomultiplier 14 is 8mm, and the gate width can be set to be 100ns to infinity; the second photomultiplier 21 has a photosurface diameter of 8mm and a gate width of 100ns to infinity.
It will be readily appreciated by those skilled in the art that the foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (8)
1. The utility model provides a high-sensitivity detection device of laser-induced breakdown spectrum aerosol single particle, its characterized in that, this detection device includes aerosol sampling unit (7), laser excitation unit (1), spectrum acquisition unit (13) and control unit (22), wherein:
the aerosol sample injection unit (7) and the laser excitation unit (1) are arranged vertically, and the aerosol sample injection unit (7) is used for collecting aerosol and forming aerosol single-particle beam;
the laser excitation unit (1) is used for generating pulse laser so as to ablate aerosol single-particle beam generated by the aerosol sample injection unit (7) and generate plasma;
the spectrum acquisition unit (13) comprises a parabolic mirror (8), a dichroic mirror (17), a first acquisition component and a second acquisition component, wherein the parabolic mirror (8) is arranged at the intersection position of the aerosol sample injection unit (7) and the laser excitation unit (1) and is used for collimating the light emitted by plasma; the dichroic mirror (17) is arranged in the propagation direction of the collimated light, and a mirror surface of the dichroic mirror forms an included angle of 45 degrees with the collimated light, and is used for separating characteristic spectral lines of elements to be detected in the collimated light so as to divide the collimated light into reflected light and transmitted light and respectively send the reflected light and the transmitted light into the first acquisition assembly and the second acquisition assembly; the first acquisition component comprises a first narrowband optical filter (16), a first focusing lens (15) and a first photomultiplier (14) which are sequentially arranged along the transmission direction of reflected light, and the first acquisition component is used for transmitting a light beam of a characteristic spectral line of a certain element to be detected and converting the light beam into an electric signal; the second acquisition component comprises a second narrow-band filter (19), a second focusing lens (18) and a second photomultiplier (21) which are sequentially arranged along the transmission direction of the transmitted light and are used for transmitting light beams of characteristic spectral lines of another element to be detected and converting the light beams into electric signals;
the control unit (22) is connected with the laser excitation unit (1) and the spectrum acquisition unit (13) and is used for controlling the testing process and collecting electric signals for analysis so as to obtain the types and the contents of elements to be detected in the aerosol single particles, and further realize the online detection of the aerosol single particles.
2. The laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device according to claim 1, wherein the aerosol sample-feeding unit (7) comprises an aerosol collector (6), an aerosol delivery element (10), an pneumatic connection element (11), a capillary tube (12) and an aspiration pump (9), wherein: the aerosol collector (6) is connected with the capillary (12) through the aerosol conveying element (10) and the pneumatic connecting element (11) in sequence so as to collect aerosol in the air and convey the aerosol into the capillary (12); the capillary tube (12) is inserted into the parabolic mirror (8) from the upper part and is used for forming aerosol single-particle beam; the air pump (9) is inserted into the parabolic mirror (8) from the lower part for recovering the exhaust gas.
3. The laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device according to claim 1, wherein the laser excitation unit (1) comprises a pulse laser (3) and a laser focusing lens (5) which are sequentially connected along a laser propagation direction, the pulse laser (3) is used for emitting pulse laser, and an optical axis of the laser focusing lens (5) is collinear with the pulse laser and is used for focusing the pulse laser on an aerosol single-particle beam so as to ablate the aerosol single-particle beam and generate plasma.
4. The laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device according to claim 1, wherein the control power supply (22) comprises a time sequence generator (2), a data acquisition card (20) and a computer (4), and the time sequence generator (2) is respectively connected with the pulse laser (3), the first photomultiplier (14), the second photomultiplier (21) and the data acquisition card (20) to trigger the operation of the same; the data acquisition card (20) is connected with the first photomultiplier (14) and the second photomultiplier (21) and is used for collecting the electric signals output by the data acquisition card; the computer (4) is connected with the data acquisition card (20) to read and analyze the electric signals to obtain the types and the contents of the elements to be detected in the aerosol single particles.
5. A laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection apparatus as claimed in claim 3, wherein the laser focusing lens (5) is an aspherical plano-convex lens coated with a laser antireflection film.
6. The laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection apparatus as claimed in any one of claims 1 to 5, wherein the parabolic mirror (8) is a parabolic mirror coated with an ultraviolet-enhanced aluminum film.
7. The laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection apparatus as claimed in any one of claims 1 to 5, wherein the dichroic mirror (17) is a long-wave-pass dichroic mirror, and the operating wavelength range is ultraviolet to near-infrared band.
8. The laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection apparatus as claimed in any one of claims 1 to 5, wherein the first narrow-band filter (16) and the second narrow-band filter (19) are narrow half-width filters and are mounted in a filter wheel to realize switching of the narrow-band filters.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211695401.4A CN116380872A (en) | 2022-12-28 | 2022-12-28 | Laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211695401.4A CN116380872A (en) | 2022-12-28 | 2022-12-28 | Laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116380872A true CN116380872A (en) | 2023-07-04 |
Family
ID=86977456
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211695401.4A Pending CN116380872A (en) | 2022-12-28 | 2022-12-28 | Laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116380872A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117571688A (en) * | 2023-11-21 | 2024-02-20 | 上海有色金属工业技术监测中心有限公司 | Laser-induced breakdown spectroscopy detection device with adjustable ablation points and control method thereof |
-
2022
- 2022-12-28 CN CN202211695401.4A patent/CN116380872A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117571688A (en) * | 2023-11-21 | 2024-02-20 | 上海有色金属工业技术监测中心有限公司 | Laser-induced breakdown spectroscopy detection device with adjustable ablation points and control method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10823679B2 (en) | Scanning type laser induced spectrum analysis and detection system | |
| CN102262075B (en) | Method for measuring elemental concentration through laser-induced breakdown spectroscopy based on spectrophotometry | |
| CN102246021B (en) | System and method for real time determination of size and chemical composition of aerosol particles | |
| CN204832513U (en) | Laser device of biological aerosol of on -line monitoring atmosphere | |
| CN105319191A (en) | Spectrograph type laser radar system detecting bioaerosol | |
| CN108169092B (en) | Online detection device and method for heavy metals and isotopes of atmospheric particulates | |
| CN101308090A (en) | Fire field multi- parameter optical maser wavelength modulated spectrum detector method and apparatus | |
| CN201083677Y (en) | Aerosol granule optical detection system | |
| CN105606571B (en) | A kind of aspherical reflective laser induction excitation of spectra/collection system | |
| CN103760136A (en) | Online monitoring system of greenhouse gas and stable isotope thereof | |
| EP3472591B1 (en) | Device and method for detecting and/or characterizing fluid-borne particles | |
| CN105651759A (en) | Surface-enhanced type Raman spectrum testing system | |
| CN116380872A (en) | Laser-induced breakdown spectroscopy aerosol single-particle high-sensitivity detection device | |
| CN101545862B (en) | Device for detecting content of suspended lead in air | |
| CN111220515A (en) | Device and method for on-line analysis of metal elements in single particles | |
| CN201210140Y (en) | Multi-parameter laser wavelength modulation spectrum detection apparatus used in fire field | |
| CN214096364U (en) | Raman probe based on double compound eye lens set | |
| US5953120A (en) | Optical probe | |
| CN112213296A (en) | Device and method for detecting uranium and plutonium content in tail gas of radioactive after-treatment plant | |
| CN208187913U (en) | Atmospheric particulates heavy metal and its isotope on-line water flushing device | |
| CN1243233C (en) | Analyser for spark through spectrum medium by laser induced | |
| CN112213297B (en) | Paraxial double-pulse LIBS system based on annular light beam | |
| CN209927723U (en) | Aerosol detection device based on laser-induced breakdown spectroscopy | |
| CN201382900Y (en) | Device for detecting suspended lead content in air | |
| CN117686481A (en) | Aerosol isotope single particle detection device based on laser multispectral |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |