Study on Dynamical and Optical Properties of Non-spherical Submicron Particles

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1) By dispersing a mixture of polystyrene (PS) latexes, doublets composed of different-diameter PS particles were obtained. The dynamic mobility diameters (Dm) of the doublets were determined by a differential mobility analyzer (DNA). The relation between Dm and the ratio a/b (a and b are the diameters of the larger and the smaller particles, respectively) was examined and interpreted in terms of the orientation of the doublets with respect to the electric field of DMA. It was also tried to produce particles of varying non-sphericity by heating and melting the doublets.2) Angular dependence of the scattered light intensity was measured for PS singlets and doublets. It was shown that the diameter of the singlets was determinable with precision of <plus-minus>0.005 mum by the comparison of the observed and calculated intensities. The intensities of light scattered by doublets were nearly twice as strong as those by singlets in every angle. This indicates that the incident light is scatte … More red independently by each particle constituting the doublet3) It was tried to prepare two additional samples of non-spherical particles. One of them was triangular or hexagonal fine gold crystals generated in a form of a hydrosol. The other one was PS particles with granules stuck on their surfaces, which were produced by dispersing PS latexes in which inorganic salts were dissolved.4) Dehydration temperature of inorganic fine crystals was determined on the basis of the change in their sizes. The temperature was found to be significantly lower than that for bulk crystals, thus revealing a size effect.5) A device was developed for measuring volume of individual aerosol particles, as the volume was considered to be a measure of size for particles of any shape. In this device, particles are evaporated in collision with a hot film sensor kept at constant temperature, and heat of vaporization is obtained from a change in voltage applied to the sensor. This device has wide applicability as an instrument for measuring a thermodynamical property of particles. Less