A multiple thin film method was developed for identification of internal mixing state of chloride and nitrate in individual aerosol particles. The film was prepared on a polycarbonate film by dual vacuum deposition of silver fluoride and nitron. We examined the applicability of the method by using particles of chloride-nitrate mixture generated by a nebulizer, and confirmed that the mixing states can be identified by the characteristic spots of AgCl ring and needle crystal. It was found that the reaction of chloride with silver fluoride and that of nitrate with nitron are promoted in the presence of water and ethanol vapors. The film was used to detect the mixing states of atmospheric aerosols collected by a low-pressure Andersen Sampler and internally mixed chloride-nitrate particles were observed by SEM (scanning electron microscope).
We studied the characteristics of the organic carbon (OC) exhaust produced by 13 heavy-duty diesel vehicles (gross weight 4,275-25,000 kg) that met the Japanese short-term or long-term standards for emissions. The vehicles were tested under city drive cycles. Eleven vehicles met the short-term standard. Their average total carbon (TC) emissions were 780 mg/km at an average vehicle speed of 8.4 km/h, 460 mg/km at 17.9 km/h, and 440 mg/km at 28.5 km/h. The average OC emission was about 35 % of the average TC emission, and the OC emission tended to decrease as the average vehicle speed increased. Four vehicles met the long-term standard. Their average TC emissions were about 80 % less than those of the vehicles that met the short-term standard, and their average OC emission was about 60 % less. The gross vehicle weight and the weight-to-power ratio (equivalent inertia weight / maximum power) are discussed as factors that might affect OC emissions. OC emissions and the OC emission ratio (OC/TC) increased when the excess power of the engine was large.
A model is developed for calculating molecule-cluster collision cross sections in homogeneous and ion-induced cluster formation. The model is applied to investigate the dependence of the molecule-cluster collision cross section of ammonia, water, argon, methanol, and methyl chloride on temperature, cluster size, and cluster charge. The calculation results show that the collision cross section is increased by the cluster charge only for clusters of the size less than about 100.