JP4337518B2 - Method and apparatus for measuring suspended aggregates - Google Patents

Description

  The present invention relates to a method and an apparatus for measuring floating aggregates, and in particular, a chain aggregate in which a large number of primary particles generated by combustion of particulate matter (PM (Particulate Matter), etc.) contained in the exhaust of a diesel engine are combined. The present invention relates to a method and an apparatus for measuring a floating aggregate for measuring the size and the number of particles of the floating aggregate.

  Conventionally, a laser-induced incandescent method (hereinafter referred to as “LII method”) is known as one of methods for measuring the particle size of a single suspended particle in the air. The LII method detects the intensity of laser-induced incandescent light from a suspended particle by irradiating the suspended particle with a pulsed laser and instantaneously raising the temperature of the suspended particle to the evaporation temperature (about 4500 ° K). The particle size is measured based on the attenuation rate of the LII signal by utilizing the fact that the attenuation rate of the detected laser-induced incandescent light intensity signal (hereinafter referred to as “LII signal”) varies depending on the particle size. That is, the particle diameter is measured by utilizing the fact that the attenuation rate of the LII signal increases as the central particle diameter decreases.

  In US Pat. No. 6,181,419 B1 (Patent Document 1), the average particle diameter is obtained from the LII signal by utilizing the ratio of the initial LII signal and the integrated value of the emission intensity as a function of the particle diameter. Are listed.

  The document “SAE 1999-01-0146” (Non-Patent Document 1) describes that the particle diameter is determined from the decay time of the LII signal.

Japanese Patent Laid-Open No. 2003-139679 (Patent Document 2) describes that an attenuation rate constant is calculated from an LII signal, and a center particle size and a distribution width are determined based on the calculated attenuation rate constant. .
US Pat. No. 6,181,419 B1 JP 2003-139679 A SAE 1999-01-0146

  However, all of the conventional techniques described above are techniques for measuring the particle size of a single particle as a size, and measuring the size of floating aggregates and the number of particles of aggregates, which are chain aggregates in which a large number of primary particles are bonded. There was a problem that it was difficult to do.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a method and apparatus for measuring a floating aggregate capable of measuring the size of the floating aggregate and the number of particles of the floating aggregate. And

  Another object of the present invention is to measure a volume equivalent particle size and a shape factor.

In order to achieve the above object, the present invention detects the intensity of incandescent light emitted by laser induction from a floating aggregate when a pulsed laser is irradiated to the floating aggregate (100) , and detects the detected incandescence. A laser-induced incandescent light total intensity signal is obtained from the light intensity (104), and a decay time of the laser-induced incandescent light intensity is obtained based on the time change of the laser-induced incandescent light total intensity signal (106), and a predetermined laser-induced incandescence is obtained. Based on the relationship between the decay time of the incandescent light intensity and the mobility particle size , and the obtained decay time of the laser-induced incandescent light intensity, the mobility particle size of the floating aggregate is obtained (108), and the mobility particle is obtained. The diameter is measured as the size of the floating aggregate.

Further, it is a method for measuring a floating aggregate having a known aggregate form factor, and detects the intensity of incandescent light emitted from the floating aggregate by laser induction when the pulsed laser is irradiated to the floating aggregate (100 ) A laser-induced incandescent light total intensity signal is obtained from the detected intensity of the incandescent light (104), and an attenuation time of the laser-induced incandescent light intensity is obtained on the basis of the time change of the laser-induced incandescent light total intensity signal (106). ), The relationship between the predetermined decay time of the laser-induced incandescent light intensity and the volume equivalent particle diameter represented by the diameter of the sphere of the volume of the aggregate and the equivalent volume, and the attenuation of the obtained laser-induced incandescent light intensity Based on the time, a volume equivalent particle diameter is determined (110), and the volume of the aggregate is determined from the volume equivalent particle diameter (112), and the predetermined aggregate volume and the laser-induced incandescent light intensity of one aggregate particle are determined. Relationship and seeking Based on the obtained volume of the aggregate, the laser-induced incandescent light intensity of one aggregate particle is obtained (114), and from the laser-induced incandescent light intensity of the one aggregate particle and the laser-induced incandescent light total intensity signal. The number of particles of the floating aggregate is obtained (116) .

The apparatus for measuring floating aggregates of the present invention utilizes the above-described method for measuring floating aggregates, and includes laser irradiation means for irradiating the floating aggregates with a pulse laser, and laser-induced incandescence from the floating aggregates. Detection means for detecting light intensity, laser-induced incandescent light total intensity signal calculating means for calculating a laser-induced incandescent light total intensity signal from the incandescent light intensity detected by the detecting means, and laser-induced incandescent light total intensity signal calculation based on the time variation of the computed laser-induced incandescence total intensity signals by means, and decay time calculating means for calculating a decay time of the laser-induced incandescence strongly light degree, and the decay time of the laser-induced incandescence strongly light degree mobility storage means for storing a relationship between the particle size, on the basis of the stored relationship in the laser-induced incandescence light strength of the decay time and the storage means calculated by the decay time calculating means, the suspended aggregates A particle size calculating means for computation of Dodo particle size, is configured to include a display unit for displaying the mobility particle size of the suspended aggregates as the size of the suspended aggregates.

The floating aggregate measuring apparatus of the present invention is a floating aggregate measuring apparatus having a known aggregate form factor, a laser irradiation means for irradiating the floating aggregate with a pulsed laser, and the floating aggregate from the floating aggregate Detection means for detecting incandescent light intensity induced by laser, laser-induced incandescent light total intensity signal calculating means for calculating a laser-induced incandescent light total intensity signal from the incandescent light intensity detected by the detecting means, and the laser-induced incandescent light based on the time variation of the computed laser-induced incandescence total intensity signals by the total intensity signal calculating means, and the decay time calculating means for calculating a decay time of the laser-induced incandescence light strength of the attenuation of the laser-induced incandescence strongly light degree time, memory means for storing a relationship between the volume equivalent diameter represented by diameter sphere volume equivalent volume of coagulation Atsumaritai, the damping time calculating means laser-induced incandescence intensity decay time which is calculated by A volume equivalent particle diameter calculating means for calculating a volume equivalent particle diameter, and an aggregate volume calculating means for calculating the volume of the aggregate from the volume equivalent particle diameter calculated by the volume equivalent particle diameter calculating means, Based on the storage means storing the relationship between the volume of the aggregate and the laser-induced incandescent light intensity of one aggregate particle, and the volume of the aggregate calculated by the volume calculation means of the aggregate, Laser-induced incandescent light intensity calculating means for agglomerates for calculating laser-induced incandescent light intensity, and laser-induced incandescent light intensity of the agglomerated particles calculated by laser-induced incandescent light intensity calculating means for the agglomerated particles And floating aggregate number calculation means for calculating the number of floating aggregate particles from the laser-induced incandescent light total intensity signal calculated by the laser-induced incandescent light total intensity signal calculation means, and the number of floating aggregate particles Calculated by the calculation means A display unit for displaying the number of particles suspended aggregates, can be configured to include.

An incandescent light emitted from the floating aggregate by laser induction when the floating aggregate is irradiated with two or more pulse lasers having different intensities , which is a method for measuring a floating aggregate whose aggregate form factor is unknown. strength respectively detect, determine the ratio of the laser-induced incandescence total intensity signal from the intensity of the detected two incandescence, from the intensity of either incandescent light of the intensity of the detected said two incandescence A laser-induced incandescent light total intensity signal is obtained, a decay time of the laser-induced incandescent light intensity is obtained based on the time change of the laser-induced incandescent light total intensity signal, Based on the relationship between the volume of the aggregate and the volume equivalent particle size represented by the diameter of the sphere of the equivalent volume and the aggregate shape factor, and the ratio of the obtained laser-induced incandescent light total intensity signal, the laser-induced incandescent light total Intensity signal ratio Volume equivalent particle size and agglomerates obtained relation shape factor, previously decay time of the laser-induced incandescence intensity which defines the volume equivalent particle size and aggregate shape represented by the diameter of a sphere of volume equivalent to the volume of the aggregates against Based on the relationship with the factor and the decay time of the laser-induced incandescent light intensity obtained, the volume equivalent particle diameter represented by the diameter of the sphere of the volume of the aggregate and the equivalent volume with respect to the decay time of the laser-induced incandescent light intensity. And the relationship between the volume equivalent particle size and the aggregate shape factor expressed by the diameter of the sphere of the volume of the aggregate and the equivalent volume with respect to the ratio of the laser-induced incandescent light total intensity signal, and the laser From the relationship between the volume of the aggregate with respect to the decay time of the incandescent light intensity and the volume equivalent particle diameter represented by the diameter of the sphere of the equivalent volume and the aggregate shape factor, the volume equivalent particle diameter and the aggregate shape factor are obtained, Is volume equivalent particle size? The volume of the aggregate is determined (112). Based on the predetermined relationship between the volume of the aggregate and the laser-induced incandescent light intensity of the aggregate and the determined volume of the aggregate, The laser-induced incandescent light intensity may be obtained (114), and the number of floating aggregate particles may be obtained from the laser-induced incandescent light intensity of one particle of the aggregate and the laser-induced incandescent light total intensity signal (116) . Furthermore, it is a measuring apparatus for a floating aggregate whose aggregate form factor is unknown, a laser irradiation means for irradiating the floating aggregate with two or more pulse lasers having different intensities, and a laser-induced incandescence from the floating aggregate A detecting means for detecting each light intensity; a ratio calculating means for a laser-induced incandescent light total intensity signal for calculating a ratio of a laser-induced incandescent light intensity signal from two incandescent light intensities detected by the detecting means; and the detection A laser-induced incandescent light total intensity signal calculating means for calculating a laser-induced incandescent light total intensity signal from the intensity of one of the two incandescent lights detected by the means, and the laser-induced incandescent light total intensity based on the time variation of the computed laser-induced incandescence total intensity signals by the signal computation means, and decay time calculating means for calculating a decay time of the laser-induced incandescence light strength of the laser-induced incandescence total The ratio of the degree signals, memory means for storing a relationship between the volume equivalent diameter represented by diameter on a volume equivalent volume sphere aggregates and aggregate form factor, the ratio calculation of the laser-induced incandescence total intensity signal The volume-equivalent particle size and coagulation expressed by the volume of the aggregate and the diameter of the sphere of the equivalent volume with respect to the ratio of the laser-induced incandescent light total intensity signal calculated by the means. Atsumaritai specific volume equivalent particle diameter to form factor laser-induced incandescence total intensity signal for calculating the relationship - and aggregate form factor computing means, and decay time of the laser-induced incandescence strongly light degree, the aggregate volume and the equivalent volume Based on the storage means storing the relationship between the volume equivalent particle size expressed by the diameter of the sphere and the aggregate shape factor, and the decay time of the laser-induced incandescent light intensity calculated by the decay time calculation means Against decay time of incandescent light intensity A volume equivalent particle diameter-aggregate shape factor calculating means for a decay time of laser-induced incandescent light intensity for calculating a relationship between a volume equivalent particle diameter expressed by a sphere of an aggregate volume and a sphere having an equivalent volume and an aggregate shape factor; Volume equivalent particle diameter to the ratio of the laser-induced incandescent light total intensity signal-expressed by the diameter of the sphere having the volume of the aggregate and the equivalent volume with respect to the ratio of the laser-induced incandescent light total intensity signal calculated by the aggregate shape factor calculating means. The volume-equivalent particle size and aggregate shape factor, and the volume-equivalent particle size-aggregate shape factor calculation means for the laser-induced incandescent light intensity decay time. The volume equivalent particle size and aggregate shape factor for calculating the volume equivalent particle size and aggregate shape factor from the relationship between the volume equivalent particle size and aggregate shape factor represented by the volume of the aggregate and the sphere diameter of the equivalent volume Performance A calculation means, a volume calculation means for the aggregate that calculates the volume of the aggregate from the volume equivalent particle diameter calculated by the volume equivalent particle diameter and the aggregate shape factor calculation means, a volume of the aggregate, and one aggregate particle Aggregates for calculating the laser-induced incandescent light intensity of one particle of the aggregate based on the storage means storing the relationship with the laser-induced incandescent light intensity and the aggregate volume calculated by the aggregate volume calculating means Laser-induced incandescent light intensity calculation means for one particle, and laser-induced incandescent light intensity and laser-induced incandescent light total intensity signal calculation of the aggregate one particle calculated by the laser-induced incandescent light intensity calculation means for the one-aggregate particle The floating aggregate particle number calculating means for calculating the number of floating aggregate particles from the laser-induced incandescent light total intensity signal calculated by the means, and the floating aggregate calculated by the floating aggregate particle number calculating means Table showing the number of particles And parts may be configured to include.

  As described above, according to the present invention, the size of the aggregate can be measured based on the decay time of the LII signal, and the aggregate particles can be measured based on the decay time of the LII signal and the absolute intensity of the LII signal. The effect that a number can be calculated is obtained.

  Moreover, the effect that a volume equivalent particle diameter and a shape factor can be measured is acquired.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a plurality of standard particles are generated from a standard particle generator, and the results of examining the relationship between the decay time of the laser-induced incandescent light intensity signal by the LII method and the size of the floating aggregate for each standard particle will be described.

  A standard particle generator (CAST: Combustion Aerosol Sandard) manufactured by Matter Engineering was used as a generation source of combustion fine particles which are standard particles. This standard particle generator generates particles by a propane gas diffusion flame, sends quenching nitrogen gas from the side at a constant height, suppresses combustion, and freezes particle growth. In this standard particle generator, the particle size of the generated particles can be changed by changing the dilution rate of the quenching nitrogen gas added to the propane gas. A part of the generated particle flow was diluted with a diluter, then taken out as test particles, and used in each measurement of a particle measuring device (SMPS), a TEM (transmission electron microscope), and an LII device described later.

  A TSI device was used as a particle measuring device (SMPS) based on the electric mobility method used for measuring the nano particles in diesel exhaust. Fine particles produced by CAST were directly introduced into a fine particle measuring apparatus, classified by DMA (electrostatic aerosol classifier: Model 3081), and the number of particles was measured by CPC (condensation nucleus counter: Model 3025A).

  A sample for electron microscope observation was collected by directly inserting a microgrid with a carbon film into the flow path of the particle flow. The collected sample was observed with a transmission electron microscope (JEOL JEM2000EX, acceleration voltage 200 kV), taken into a personal computer, and then processed and analyzed with image analysis software.

  As the LII apparatus, an apparatus similar to the LII apparatus of the present embodiment was used. FIG. 1 shows an outline of the LII apparatus according to the present embodiment.

  The LII apparatus includes a pulsed laser apparatus 10 that irradiates a measurement object such as a floating aggregate with a pulse laser as excitation light. On the laser beam irradiation side of the pulsed laser device 10, an aperture 12 for cutting out the laser beam, an ND filter 14 for adjusting the intensity of the laser beam, and a beam splitter 16 for branching the laser beam from the main optical path are sequentially arranged. Yes. A photodiode 18 for monitoring the laser beam is disposed on the laser beam branching side of the beam splitter 16.

  The laser beam in the main optical path on the laser beam transmitting side of the beam splitter 16 is divided into two by the beam splitter 19 and the like. The bisected laser light is converted into two excitation lights having different intensities by ND filters 21 and 21 ', respectively. Cylindrical lenses 20 and 20 '(for example, f = 100 mm) for condensing the laser light are disposed in the LII observation quartz cylindrical cells 22 and 22' in the optical paths of the two laser lights.

  Radiation light, which is incandescent light emitted by laser excitation from floating particles such as soot particles existing in the LII observation quartz cylinder cells 22 and 22 ′, is provided on the side of the LII observation quartz cylinder cells 22 and 22 ′. Photomultiplier tubes 24 and 24 'for detection are arranged. A partition plate 25 for blocking one radiation light (LII light) is provided at the center of the LII observation quartz cylindrical cells 22 and 22 '.

  Between the LII observation quartz cylindrical cell 22 and the photomultiplier tube 24, a cylindrical lens 26, an aperture 28, and an interference filter 30 for performing wavelength selection (for example, a center wavelength of 355 nm and a half-value width of 16.7 nm) are arranged. ing. The photomultiplier tube 24 is connected to a digital oscilloscope 34 via a high-speed amplifier 32. Similarly, between the LII observation quartz cylindrical cell 22 ′ and the photomultiplier tube 24 ′, a cylindrical lens 26 ′, an aperture 28 ′, and an interference filter 30 ′ that performs wavelength selection (for example, a central wavelength of 355 nm, a half wavelength) The value width 16.7 nm) is arranged. The photomultiplier tube 24 'is connected to the digital oscilloscope 34 via a high-speed amplifier 32'.

  In this LII apparatus, the second harmonic (532 nm) of an Nd: YAG laser was used as excitation light.

  Using each of the above devices, a particle group of six particle size modes, Mode 1 to Mode 6 (Mode 1 to Mode 6), was generated by CAST and used for measurement. FIG. 3 shows the particle size distribution (distribution of the number of particles with respect to mobility particle size (Mobility particle size)) of each mode measured by SMPS. Each mode has a distribution shape close to a normal logarithmic distribution, and the median diameter changes in a range of about 30 nm to 170 nm. Table 1 summarizes the SMPS median diameter of each mode.

  FIG. 4 shows representative TEM images of the particles in each mode. On the small particle size side, the particles have a shape close to a single spherical shape, and in the form of a chain aggregate in which a large number of primary particles are bonded toward the large particle size side. From this, it can be seen that in the standard particles used this time, the morphology of the particles changes as the particle size grows.

  In order to examine the relationship between the mobility particle size in FIG. 3 and the particle size observed by TEM, TE-images of several hundred particles were statistically analyzed. As the particle diameter observed by TEM, the swirling particle diameter shown in FIG. 6 (a), the maximum particle diameter shown in (b), the average ferret diameter shown in (c), and the area equivalent particle diameter shown in (d) are used. It was.

  FIG. 5 shows the distribution of the swirling particle size. In the figure, the particle size distribution by SMPS in FIG. Although there is a shift on the low particle size side, it can be said that the distribution of both is generally similar.

  Similarly, another particle size defined in FIG. 6, (b) maximum particle size, (c) average ferret size, and (d) area equivalent particle size were also analyzed. Although the description of each distribution graph is omitted, the correlation between the average value and the average mobility particle size is plotted in FIG. A broken line in the figure indicates an equal particle diameter line. From FIG. 7, it can be understood that the swirling particle diameter shows the best coincidence with the mobility particle diameter in the standard particles.

  Next, soot concentration and particle size measurement by the LII method was studied. FIG. 8 shows the laser beam intensity dependence of the absolute intensity of the LII signal for each particle size mode. The absolute intensity of the LII signal increases in proportion to the change of the laser intensity in the initial stage, but decreases after taking the maximum value once. The reason is considered to be that soot particles are evaporated in the region where the laser beam is strong. In the present invention, in order to avoid this influence, data of the maximum laser intensity (for example, the intensity of 4 mJ / pulse indicated by a broken line in the figure) before the saturation of the LII signal is used for the analysis.

  First, in order to examine the relationship between the soot concentration and the LII signal intensity (LII intensity), the relationship between the separately measured weight concentration of elemental carbon (EC) and the intensity of the LII signal is plotted in FIG. In the figure, the median diameter of SMPS is shown. From FIG. 9, it can be understood that in the particle size range (for example, 30 to 170 nm), the intensity of the LII signal is proportional to the EC concentration regardless of the particle size. From this, it was confirmed that the soot weight concentration can be measured from the absolute intensity of the LII signal even under conditions in which the particle size changes greatly.

  Next, particle diameter measurement by the LII apparatus will be described. In this case, the LII signal intensity at one of the laser intensities is used. FIG. 10 shows changes with time in the LII signal intensity in each of the modes 1 to 6. The LII signal intensity decay time increases monotonically in the order of modes 1-6. It can be seen from the TEM image in FIG. 4 that the primary particle diameter does not increase monotonically in the order of modes 1 to 6, and the decay time of the LII signal does not correspond to the size of the primary particle diameter.

  On the other hand, as shown in FIG. 11, the decay time of the LII signal monotonously increases with respect to the SMPS median diameter, that is, the aggregate size (mobility particle size). It can be judged that it depends on the size of the soot aggregate rather than the diameter.

  In the LII method, soot is heated by light absorption and then cooled by thermal radiation to attenuate radiation light. The absorbed energy is proportional to the particle volume, whereas the cooling rate is proportional to the particle surface area, so the decay rate of the LII signal depends on the specific surface area of the particle (= particle surface area / particle volume). Therefore, the reason that the decay time of the LII signal depends on the aggregate size can be estimated that the surface area of the primary particles is gradually covered by the growth of the aggregates, and the specific surface area of the particles is reduced accordingly. .

  In order to confirm the above estimation, the specific perimeter defined by the following equation (1) was analyzed for the TEM image.

(Specific circumference) = (particle circumference) / (particle area) (1)
Originally, it is necessary to examine whether this specific perimeter is appropriate as a substitute for the specific surface area of a three-dimensional material, but this time it was used only for the purpose of grasping a qualitative tendency. FIG. 12 shows the correlation between the specific perimeter length of each mode 1 to 6 and the swirling particle diameter. In either mode, the specific perimeter tends to decrease with increasing particle size. FIG. 13 shows the relationship between the average value of the specific peripheral length of each mode 1 to 6 and the median diameter of the SMPS. From this figure, the specific peripheral length is monotonous as the particle size increases. It can be understood that the number has decreased. From these facts, it is presumed that there is a considerable correlation between the particle size of the aggregate and the specific surface area of the particles, though indirectly.

  From the above results, it is considered that the specific surface area of the agglomerates also decreases with an increase in the particle size, and as a result, the correspondence shown in FIG. 11 appears between the decay time of the LII signal intensity and the particle size. The above results indicate that the size of the aggregate can be measured from the decay time of the LII signal of the LII device.

  That is, if the decay time of the LII signal is measured, the mobility particle size (mobility particle size) of the aggregate can be measured as the aggregate size from the measured decay time of the LII signal and the relationship of FIG. .

Next, in order to obtain the number of particles in the aggregate, a shape factor α representing the amount of deviation from the sphere is defined as a factor of the specific surface area of the particle, and the volume represented by the diameter of the sphere having an equivalent volume to the volume of the aggregate when the equivalent particle diameter is D, and the surface area of the aggregate of the combustion particles was expressed as απD ^3/6. The shape factor α representing the amount of deviation is α = 1 when the combustion particle is a sphere, and α> 1 when the shape is deviated from the sphere like an aggregate.

  FIG. 14 shows the relationship between the volume of one aggregate particle and the intensity of the LII signal when α = 1, 5, and 10. FIG. 15 shows the volume equivalent of the aggregate when α = 1, 5, and 10. The relationship between a particle size and the decay time of a LII signal is shown.

As for the soot aggregates produced by combustion, the shape of the particles is roughly known, so the value of the shape factor α is determined in advance by experiments. Since the shape factor α is known, the volume equivalent particle diameter D (for example, 80 nm) can be obtained from the decay time of the LII signal and the relationship shown in FIG. The volume of a single aggregate (for example, 2.7 × 10 ⁵ nm ³ ) is determined from the determined volume equivalent particle diameter D, and the LII per aggregate particle is determined from the determined volume and the relationship shown in FIG. The signal strength is required.

Total LII intensity = LII intensity per aggregate particle × number of particles (2)
Therefore, when the shape factor α is known, the aggregate size (volume equivalent particle diameter) and the number of particles can be obtained from the intensity of the LII signal (total signal intensity of LII) and the decay time of the LII signal. it can.

  Therefore, in the present embodiment, the memory of the digital oscilloscope 34 stores, in the memory of the digital oscilloscope 34, the first map showing the relationship between the decay time of the LII signal and the mobility particle size shown in FIG. ) And the intensity of the LII signal per particle, and a third map indicating the relationship between the volume equivalent particle diameter and the LII signal decay time shown in FIG. The measurement routine program shown in FIG. 2 is stored in advance.

  Next, the measurement routine of FIG. 2 will be described. In step 100, the LII signal is captured, and the LII signal captured in step 102 is converted into a digital value. In step 104, the intensity of the LII signal is calculated, and in step 106, the decay time of the LII signal is calculated.

  In step 108, based on the LII signal decay time calculated in step 106 and the first map, the mobility particle size corresponding to the LII signal decay time is calculated as the aggregate size. In step 110, step 110 is performed. Based on the decay time of the LII signal calculated in 106 and the third map, the volume equivalent particle diameter D is calculated, and in step 112, the predetermined shape factor α and the calculated volume equivalent particle diameter D are obtained. After calculating the volume based on this, in step 114, the intensity of the LII signal of one particle is calculated based on the calculated volume and the second map.

  In step 116, the number of aggregate particles is determined from the intensity of the LII signal of one particle and the intensity of the LII signal (total signal intensity of the LII signal). In step 118, the mobility particle diameter calculated in step 108 or The volume equivalent particle diameter calculated in step 110 and the number of particles calculated in step 116 are displayed on the display unit of the digital oscilloscope 34.

  As described above, according to the present embodiment, the size of the aggregate can be measured based on the decay time of the LII signal, and the aggregate can be measured based on the decay time of the LII signal and the intensity of the LII signal. The number of particles can be calculated.

  Next, a method for determining the volume equivalent particle diameter D and the shape factor α of the aggregate particles whose shape factor α is unknown will be described. In this case, the ratio of the LII signal intensity at the two laser intensities, the LII signal decay time, and the following two maps are used. Further, the shape factor α is defined as follows as an amount representing how much the particle specific surface is compared to a sphere.

Surface area to volume equivalent particle diameter D (in the case of a sphere) when πD ^3/6 α = 1 and becomes. The shape factor alpha = alpha to the particle surface area is α'πD ^3/6 relative to the volume equivalent particle diameter D becomes '(α'> 1).

16 and 17 show the volume equivalent particle diameter D and the shape factor α with respect to the ratio of the LII signal intensity at the two laser intensities when the laser intensities of the two laser lights are 570 mJ / cm ² and 285 mJ / cm ² . It is a map which shows a contour map.

18 and 19 are maps showing contour maps of the volume equivalent particle diameter D and the shape factor α with respect to the LII signal decay time when the laser intensity is 570 mJ / cm ² .

  These maps are stored in advance in the memory of the digital oscilloscope 34.

  As described with reference to FIG. 2, the digital oscilloscope 34 calculates the LII signal intensity of the two laser intensities, calculates the ratio of the LII signal intensity of the two laser intensities, and calculates the LII decay time. Then, based on the above map, the contour line of D-α with respect to the ratio of the LII signal intensity at the two laser intensities and the contour line of D-α with respect to the LII signal decay time are obtained, and the volume equivalent particle is obtained by superimposing these contour lines. The diameter D and the shape factor α are obtained. For example, when the LII signal intensity ratio is 0.5 and the LII signal decay time is 5 ns, the shape factor is approximately 4 and the volume equivalent particle diameter is approximately 35 nm by overlapping two contour lines. .

  The number of particles can be determined from the obtained volume equivalent particle diameter D, the shape factor α, and the absolute intensity of the LII signal according to the procedure shown in FIG. For particles with known aggregate shape factor α, the aggregate size (by measuring the ratio of LII signal intensity at two laser intensities or LII signal decay time and the absolute intensity of the LII signal) Volume equivalent particle diameter) and the number of particles can be determined.

  The above map can be obtained by numerical simulation, or can be obtained experimentally using standard particles or the like.

It is the schematic of embodiment of this invention. It is a flowchart which shows the measurement routine of embodiment of this invention. It is a diagram which shows the relationship between the particle size by the fine particle measuring device (SMPS) of standard particles, and the number of particles. It is the schematic which shows the typical TEM image of a standard particle. It is a diagram which shows the expansion | deployment diameter distribution of a standard particle. It is the schematic for demonstrating the definition of the particle size used by TEM image analysis. It is a diagram which shows the correlation with the particle size and TEM particle size by a fine particle measuring device (SMPS). It is a diagram which shows the laser beam intensity | strength dependence of the absolute intensity | strength of a LII signal. It is a diagram which shows the EC density | concentration dependence of the absolute intensity of a LII signal. It is a diagram which shows a time-dependent change of a LII signal. It is a diagram which shows the relationship between the decay time of a LII signal, and a mobility particle size. It is a diagram which shows the relationship between specific circumference and an average expansion | deployment diameter (swivel particle size). It is a diagram which shows the relationship between average specific circumference and average mobility particle size. It is the diagram which showed the relationship between the volume of a single particle, and the intensity | strength of a LII signal about (alpha) = 1,5,10. It is the diagram which showed the relationship between the volume equivalent particle size in the case of an aggregate about α = 1,5,10, and the intensity | strength of a LII signal. It is a map which shows the contour map of the volume equivalent particle diameter D and the shape factor (alpha) with respect to the ratio of the LII signal intensity | strength in two laser intensity | strengths. It is a map which shows the same contour map as FIG. It is a map which shows the contour map of the volume equivalent particle diameter D with respect to LII signal decay time, and the shape factor (alpha). It is a map which shows the same contour map as FIG.

Explanation of symbols

10 Pulsed Laser Device 22 Quartz Cylindrical Cell for LII Observation 24 Photomultiplier Tube 34 Digital Oscilloscope

Claims (6)

Detecting the intensity of incandescent light emitted from the floating aggregate when the pulsed laser is irradiated to the floating aggregate (100) ;
A laser-induced incandescent light total intensity signal is obtained from the detected incandescent light intensity (104),
Determining the decay time of the laser-induced incandescent light intensity based on the time change of the laser-induced incandescent light total intensity signal (106);
Based on a predetermined relationship between the decay time of the laser-induced incandescent light intensity and the mobility particle size , and the obtained decay time of the laser-induced incandescent light intensity, the mobility particle size of the floating aggregate is obtained (108). ,
Measuring the mobility particle size as the size of floating aggregates ,
Method for measuring suspended aggregates. A method for measuring suspended aggregates with known aggregate form factors,
Detecting the intensity of incandescent light emitted from the floating aggregate when the pulsed laser is irradiated to the floating aggregate (100) ;
A laser-induced incandescent light total intensity signal is obtained from the detected incandescent light intensity (104),
Determining the decay time of the laser-induced incandescent light intensity based on the time change of the laser-induced incandescent light total intensity signal (106);
The relationship between the predetermined decay time of the laser-induced incandescent light intensity and the volume equivalent particle diameter represented by the sphere diameter of the volume of the aggregate and the equivalent volume, and the obtained decay time of the laser-induced incandescent light intensity. Based on the volume equivalent particle size (110),
Determining the volume of the aggregate from the volume equivalent particle diameter (112);
Based on the relationship between the predetermined volume of the aggregate and the laser-induced incandescent light intensity of the aggregate one particle, and the determined volume of the aggregate, the laser-induced incandescent light intensity of the aggregate one particle is obtained (114) ,
The number of particles in the floating aggregate is determined from the laser-induced incandescent light intensity of the one aggregate particle and the laser-induced incandescent light total intensity signal (116),
Method for measuring suspended aggregates. A method for measuring floating aggregates whose aggregate form factor is unknown,
Detecting the intensity of incandescent light emitted from the floating aggregate when the floating aggregate is irradiated with two or more pulse lasers having different intensities, respectively ,
Obtain the ratio of the total intensity signal of the laser-induced incandescent light from the intensity of the two incandescent lights detected,
A laser-induced incandescent light total intensity signal is obtained from the intensity of one of the two incandescent lights detected ,
Determine the decay time of the laser-induced incandescent light intensity based on the time change of the laser-induced incandescent light total intensity signal ,
The ratio of the predetermined laser-induced incandescent light total intensity signal, the relationship between the volume of the aggregate and the volume equivalent particle size expressed by the diameter of the sphere of the equivalent volume and the aggregate form factor, and the obtained laser-induced incandescence Based on the ratio of the total light intensity signal, the relationship between the volume of the aggregate and the volume of the aggregate and the shape factor of the aggregate represented by the sphere diameter of the equivalent volume with respect to the ratio of the laser-induced incandescent light total intensity signal
Based on the relationship between the predetermined decay time of the laser-induced incandescent light intensity, the volume equivalent particle size and the aggregate shape factor, and the obtained decay time of the laser-induced incandescent light intensity, the decay time of the laser-induced incandescent light intensity The relationship between the volume of the aggregate and the volume equivalent particle size expressed by the diameter of the sphere of the equivalent volume and the aggregate shape factor is obtained.
The relationship between the volume of the aggregate and the volume equivalent particle size represented by the diameter of the sphere of the equivalent volume to the ratio of the laser-induced incandescent light total intensity signal and the aggregate shape factor, and the aggregate with respect to the decay time of the laser-induced incandescent light intensity From the relationship between the volume equivalent particle size and the aggregate shape factor represented by the volume of the sphere of the equivalent volume and the aggregate shape factor, the volume equivalent particle size and the aggregate shape factor are obtained,
Determining the volume of the aggregate from the volume equivalent particle diameter (112);
Based on the relationship between the predetermined volume of the aggregate and the laser-induced incandescent light intensity of the aggregate one particle, and the determined volume of the aggregate, the laser-induced incandescent light intensity of the aggregate one particle is obtained (114) ,
The number of particles in the floating aggregate is determined from the laser-induced incandescent light intensity of the one aggregate particle and the laser-induced incandescent light total intensity signal (116),
Method for measuring suspended aggregates. Laser irradiation means for irradiating the floating aggregate with a pulsed laser;
Detection means for detecting incandescent light intensity induced by laser from the floating aggregate;
A laser-induced incandescent light total intensity signal calculating means for calculating a laser-induced incandescent light total intensity signal from the incandescent light intensity detected by the detecting means;
Based on the time variation of the laser-induced incandescence total intensity signal calculated by said laser-induced incandescence total intensity signal calculating means, and the decay time calculating means for calculating a decay time of the laser-induced incandescence strongly light degree,
Storage means for storing the relationship between the decay time of the laser-induced incandescence strongly light degree and the mobility diameter,
A particle size computing means for the damping time calculation means laser-induced incandescence light strength of the decay time and which is calculated in the basis of the stored relationship in the storage means, for computation mobility particle size of the suspended aggregates,
A display unit for displaying the mobility particle size of the floating aggregate as the size of the floating aggregate;
An apparatus for measuring floating aggregates. An apparatus for measuring suspended aggregates with known aggregate form factors,
Laser irradiation means for irradiating the floating aggregate with a pulsed laser;
Detection means for detecting incandescent light intensity induced by laser from the floating aggregate;
A laser-induced incandescent light total intensity signal calculating means for calculating a laser-induced incandescent light total intensity signal from the incandescent light intensity detected by the detecting means ;
Based on the time variation of the laser-induced incandescence total intensity signal calculated by said laser-induced incandescence total intensity signal calculating means, and the decay time calculating means for calculating a decay time of the laser-induced incandescence strongly light degree,
And decay time of the laser-induced incandescence strongly light degree, a storage means for storing a relationship between the volume equivalent diameter represented by diameter sphere volume equivalent volume of coagulation Atsumaritai, laser calculated by the decay time calculating means A volume equivalent particle diameter calculating means for calculating a volume equivalent particle diameter based on the decay time of the incandescent light intensity,
An aggregate volume calculating means for calculating the volume of the aggregate from the volume equivalent particle diameter calculated by the volume equivalent particle diameter calculating means;
Based on the storage means storing the relationship between the volume of the aggregate and the laser-induced incandescent light intensity of one aggregate particle, and the volume of the aggregate calculated by the volume calculation means of the aggregate, Means for calculating laser-induced incandescent light intensity of a single aggregate particle for calculating laser-induced incandescent light intensity;
The laser-induced incandescent light intensity calculated by the laser-induced incandescent light intensity calculating means of the aggregate one particle and the laser-induced incandescent light total intensity signal calculated by the laser-induced incandescent light total intensity signal calculating means. The floating aggregate particle number calculating means for calculating the floating aggregate particle number from
A display unit for displaying the number of floating aggregate particles calculated by the floating aggregate particle number calculating means ;
An apparatus for measuring floating aggregates. An apparatus for measuring floating aggregates whose aggregate form factor is unknown,
Laser irradiation means for irradiating two or more pulsed lasers having different intensities to the floating aggregate;
Detection means for detecting incandescent light intensity induced by laser from the floating aggregate,
A ratio calculating means for a laser-induced incandescent light total intensity signal for calculating a ratio of a laser-induced incandescent total light intensity signal from two incandescent light intensities detected by the detecting means ;
A laser-induced incandescent light total intensity signal calculating means for calculating a laser-induced incandescent light total intensity signal from the intensity of one of the two incandescent lights detected by the detecting means;
Based on the time variation of the laser-induced incandescence total intensity signal calculated by said laser-induced incandescence total intensity signal calculating means, and the decay time calculating means for calculating a decay time of the laser-induced incandescence strongly light degree,
A storage means for storing a ratio of a laser-induced incandescent light total intensity signal, a volume equivalent particle diameter expressed by a sphere diameter of an aggregate volume and an equivalent volume, and an aggregation shape factor; and the laser-induced incandescent light total Based on the ratio of the laser-induced incandescent light total intensity signal calculated by the intensity signal ratio calculation means, the volume of the aggregate and the volume of the sphere of the equivalent volume with respect to the ratio of the laser-induced incandescent light total intensity signal Volume equivalent particle size-aggregate shape factor calculating means for the ratio of the laser-induced incandescent light total intensity signal for calculating the relationship between the equivalent particle size and the aggregate shape factor;
A laser-induced incandescence light strength of the decay time, and storage means for storing a relationship between the volume and the equivalent volume of the volume equivalent particle size and aggregate shape factor represented by the diameter of the spherical aggregates, the damping time calculating means Based on the decay time of the laser-induced incandescent light intensity calculated in step 1, the volume-equivalent particle size and aggregate form factor represented by the sphere diameter of the aggregate volume and the equivalent volume with respect to the decay time of the laser-induced incandescent light intensity A volume-equivalent particle diameter-aggregate shape factor calculating means for the decay time of the laser-induced incandescent light intensity for calculating the relationship of:
Volume equivalent particle diameter to the ratio of the laser-induced incandescent light total intensity signal-expressed by the diameter of the sphere having the volume of the aggregate and the equivalent volume with respect to the ratio of the laser-induced incandescent light total intensity signal calculated by the aggregate shape factor calculating means. The volume-equivalent particle size and aggregate shape factor, and the volume-equivalent particle size-aggregate shape factor calculation means for the laser-induced incandescent light intensity decay time. The volume equivalent particle size and aggregate shape factor for calculating the volume equivalent particle size and aggregate shape factor from the relationship between the volume equivalent particle size and aggregate shape factor represented by the volume of the aggregate and the sphere diameter of the equivalent volume Computing means;
Aggregate volume calculating means for calculating the volume of the aggregate from the volume equivalent particle diameter and the volume equivalent particle diameter calculated by the aggregate shape factor calculating means,
Based on the storage means storing the relationship between the volume of the aggregate and the laser-induced incandescent light intensity of one aggregate particle, and the volume of the aggregate calculated by the volume calculation means of the aggregate, Means for calculating laser-induced incandescent light intensity of a single aggregate particle for calculating laser-induced incandescent light intensity;
The laser-induced incandescent light intensity calculated by the laser-induced incandescent light intensity calculating means of the aggregate one particle and the laser-induced incandescent light total intensity signal calculated by the laser-induced incandescent light total intensity signal calculating means. The floating aggregate particle number calculating means for calculating the floating aggregate particle number from
A display unit for displaying the number of floating aggregate particles calculated by the floating aggregate particle number calculating means;
An apparatus for measuring floating aggregates.

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