For basic investigations on small particles or clusters a number of experiments use Suspension of the finely dispersed material in a gas. Examples of such experiments that have led or may lead to discovery of interesting properties of small particles are reviewed. Most of the review deals with aerosol photoemission (APE), as well as its application in measurement of gas adsorption to small particles. A method of sensitive detection of size changes of aerosol particles in the sub-monolayer range together with an application is reviewed as a further method of adsorption measurement. The newest result in X-ray absorption spectroscopy on aerosol particles is shown. Finally, the possibility of measuring aerosol coagulation with the aim of estimating forces between particles is explained and surprising results obtained with this method are mentioned.
Photodissociation rate of atmospheric minor constituents in antarctic winter was studied on the numerical model including spherical atmosphere effect and taking it into consideration that the scattering effect of PSC (Polar Stratospheric Clouds) on photodissociation. Diffusion of solar radiation into the lower stratosphere was suggested during antarctic winter period. Therefore significant photodissociation is expected even in winter time. For example, the ratio of the photodissociation rate at solar zenith angle θ0 = 90 ° to that at θ0 = 60 ° for Chappius band of ozone is 59.2 %. Within the value for PSC, 8 % increase of flux was found at wavelength λ =755 nm comparing the value for PSC free condition for θ0 = 80 °, and photodissociation rates of ozone (Chappius band), ClONO2, and HOCl showed a 2 % increase. However, a 2 % decrease in the rate was found for O2. Summarizing the results of calculation, the effect of PSC on the photo- dissociation process can advance even in antarctic winter.
The performance of an aerosol generator that nebulizes PSL (polystyrene latex) suspensions was evaluated in the size range between 0.1 to 0.3 μm. The PSL size distribution spectra under various generating conditions were obtained with two laser particle counters in parallel and a multi-channel analyzer. The stability of the algorithm for the location parameters and the widths of the spectra was investigated first. On this basis, the variability of the generation was evaluated separately from the measurement errors. The reproducibility of the mean particle size thus found was better than 1 %. When the concentration of the generated PSL exceeded 106 particles/l, the mean size was observed to decrease, which may be attributed to the signal processing characteristics of the counters used in the experiment. The other factors including centrifugation of the PSL suspension, nebulizing and drying air flow rates and variability of the nebulizers were found to have smaller effects on the mean size. The applicability of the generation method to the public inspection service of laser particle counters is discussed on the basis of the results.