After a critical evaluation of published data on complex refractive indices of carbon particles and soot, optical properties of carbon particles ranging from 0.2 to 100 μm were evaluated with the Mie calculation from a viewpoint of aerosol effects on the global warming. The facts are made clear ; the maximum of absorption efficiency Qabs is around α = 1, and Qabs of submicron particle in visible range is higher than that in infrared range ; Qabs is not so affected by the change of an imaginary part of refractive index k, if k > 2.5 ; a single single albedo of carbon aerosol particle is estimated about 0.5 for a representative complex refractive index derived from the published data. Temperature of surface is surely to be affected by carbon aerosol particles ; the temperature will be dropped by carbon particles in the stratosphere, and be warmed by those in the troposphere.
A simple technique to estimate the refractive index of polystyrene latex (PSL) particles in water was proposed. The imaginary part of the refractive index was determined from the number concentration and the size distribution of PSL particles. It was found to be below 0.01, and was negligibly small in this experiment. The real part of the refractive index was obtained from the wave length of the first maximum in the extinction curve. It decreased from 1.615 to 1.585 in accordance with the change of wave length from 0.4 to 0.65 μm at 293K, and decreased from 1.59 to 1.565 with the temperature change from 293 to 313 K at the wave length of 0.6 μm.
Mixing type CNC (Condensation Nucleus Counter), one of the typical three types of CNC's, where an aerosol is mixed with heated air saturated by a certain vapor to produce supersaturation, has been evaluated. Counting efficiency of the CNC (flow rate : 2.8 l/min, particle size : 4-20 nm) was observed by an electrometer for three kinds of condensing vapor, 1)ethylene-grycol, 2) di-ethylene-grycol and 3) tri-ethylene-grycol. The best result, where efficency was about 70 % with 5 nm particles, was observed for di-and tri-ethylene-grycol vapor. Experimental results are discussed from the view point of super-saturation produced and the amount of condensing vapor which are calculated for various operating conditions and vapor used, and factors affecting performance of mixing type CNC have been made clear.
Air ionization has been used for electro-static control of the semi-conductor industries. The conventional-type ionizers have the defect : creating small particles from the discharge emitters. There are two sources of the particle generation. One is eroded surfaces of emitters and the other is deposits on the emitters. We have analyzed the erosion and contamination of air ionizer emitters with various characterization technologies : Corona Discharge Spectroscopy, Atomospheric Pressure Ionization Mass Spectrometer (APIMS), Auger Electron Spectroscopy (AES), Electron Probe Microanalysis (EPMA), Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Diffractmetry (XRD). The particle generation from metallic emitters themselves is induced by oxidation of emitter surfaces due to corona discharge. Deposits on the emitters consist of the following materials : oxidized metallic compounds, SiO2 material formed from ultra-fine aerosol particles penetrating through ULPA filters, inorganic compounds of carbonate and nitrate synthesized from ambient air, and organic compounds of carboxylic acid or ammonium oxalate synthesized from organic solvent vapor.
Production and concentration of nanometer-sized Ag particles in organic solvents was carried out with surfactant by means of a gas flow-cold trap method combined with gas evaporation technique. Although the concentration process of the colloidal solution caused aggregation of the particles, the isolation of individual particles from each other was maintained very well by the surfactant layer. The preservation of particle size in the concentration process was also checked and verified with an electron microscopy and a photon correlation spectroscopy.