Two up-to-date trace-level microbeam techniques were presented for single particle analysis of collected atmospheric aerosols and water droplets such as fog and raindrops. One is micro synchrotron radiation X-ray fluorescence (μ-SRXRF) , that is, a combination of X-ray microprobe and XRF analysis. Description was made on the scanning X-ray microprobe system at SPring-8, which is the world's largest third-generation synchrotron radiation facility, BL-37XU (Beamline 37XU) which can provide not only qualitative and quantitative information of ultra trace elements in single particles but also chemical state information of an element in the individual particles by XANES (X-ray Absorption Near Edge Structure) measurements. The X-ray microprobe system was applied to ultra trace characterization of single Kosa particles and fixed fog droplets with cyanoacrylate vapor. Micro proton induced X-ray emission technique (μ-PIXE) of large reaction cross section is also a promising method for single particle analysis of aerosols and droplets, and instrumentation of the μ-PIXE system at Takasaki Ion Accelerators for Advanced Radiation Application, Japan Atomic Energy Research Institute (TIARA, JAERI) was briefly described. The problem encountered in both techniques was discussed.
This paper gives descriptions of instrumentation of aerosol mass-spectrometry (MS) as well as the conventional MS. Measurement with aerosol MS consists of sample introduction, particle sizing, ionization and mass spectrometry. The ionization efficiencies due to various methods, such as electron impact, laser and inductively coupled plasma are compared and the advantages and disadvantages of Time-of-Flight MS and quadrupole MS are discussed for applying mass-spectrometry to aerosol measurements.
Three measurement techniques that have been developed in the last few years for online determination of the chemical composition of sub-100 nm atmospheric aerosol particles are reviewed. They include the thermal desorption particle beam mass spectrometer (TDPBMS) , the thermal desorption chemical ionization mass spectrometer (TDCIMS) , and the aerosol mass spectrometer (AMS) . The measurement principles of these techniques are described with results of chemical analyses of sub-100 nm atmospheric and diesel exhaust particles by them. Strengths and weaknesses of the three techniques are discussed.
Atmospheric aerosol particles are present as the mixture of various components. Knowledge of the composition and state of mixture of individual aerosol particles is important for evaluating the effect of aerosols on atmospheric environment, in particular atmospheric radiation and cloud formation. The method of electron microscopy for examining the composition and mixing properties of individual aerosol particles is reviewed in this paper.
Information on the distribution of chemical composition with respect to particle size is necessary in various fields of aerosol research. Particle analyzer system using helium microwave-induced plasma (He-MIP) can simultaneously measure the composition and size of individual particles without any preparation, but the plasma is relatively unstable because of its low plasma capacity. We have overcome this difficulty by devising new single particle introduction system for He-MIP. Furthermore, we have developed a high-sensitivity in-situ measurement technology using Laser Induced Breakdown Spectroscopy (LIBS). This measurement technology couples new particle-plasmatizing technique with high-sensitivity measurement of photons from visible to ultraviolet wavelength bands emitted from the plasma, therefore allowing simultaneous stable measurement of particle size and composition as required in various processes.
Unique behavior of nanoparticles has attracted a great deal of attention from mainly two points of view, i.e. an intensified reactivity due to large surface-to-volume ratios and novel electronic properties due to the quantum size effect. Development of optical measurement methods for nanoparticles suspended in vacuum or gas flow is very important not only for an in situ particle monitoring in gas phase but also for scientific study of semiconductor nanoparticles or clusters, because the optical properties are influenced by the surface conditions or the surrounding matter. This review introduces recent progress in spectroscopic studies of semiconductor nanoparticles in vacuum or gas flow.
A moment method of a q-th order extended log-normal size distribution (ELND) is established for the Brownian aerosol coagulation in a wide range from the free-molecule to the continuum regimes, in order to readily apply the moment method to not only log-normal distribution (LND) but also zeroth-order logarithmic distribution (ZOLD) . We can easily choose LND or ZOLD in the ELND moment method by merely altering q (q =-1 or 0, respectively) . Since the moment method of ZOLD has not been established in a wide coagulation regime, ZOLD was mainly examined by using the ELND moment method. The results of the ELND moment method are similar to those of the volume-conserving sectional method. For total particle number per unit volume and total surface area per unit volume, the differences between the moment and the sectional methods are within 4 % in the cases of initial standard deviations of 1.5 and 1.75. The results are insensitive to the time step size used in numerical time integration (the fourth-order Runge-Kutta method) , when the time step size is shorter than 4800 s. The simple ELND moment method is expected to be widely used, when the observational and experimental results described by LND and ZOLD are examined in large-scale scientific simulations of environmental and climate changes.
Particle size distribution of cigarette side-stream smoke (CSSS) was measured just above the burning tip with a laser light scattering method. 2-D polarization-sensitive laser light scattering (2DPLLS) system was applied to the in situ measurement of CSSS since this method can acquire the spatial distribution of particle mean diameter with ICCD camera. It was found that the particle mean diameter was 0.33 μm with the geometric standard deviation of 1.3, in favorable comparison to the particle mean diameter of 0.24 μm with the geometric standard deviation of 1.1 at 2 mm above the burning tip, which was measured by 1-D multi-angle laser light scattering (1DLLS) method. Furthermore, we measured the entire particle size distribution using a scanning mobility particle sizer (SMPS) and obtained the particle mean diameter of 0.17 μm with the geometric standard deviation of 1.5. The values obtained in the present work were reasonably in good agreement with those reported by other researchers using ex situ methods. Consequently, we concluded that the in situ 2DPLLS method is suitable for the measurement of CSSS.