ELUCIDATION OF GENERATION AND GROWTH MECHANISMS OF SECONDARY PARTICLES

为了评估和预防二次气溶胶颗粒对大气环境和人类健康的影响，本报告研究了颗粒的产生机制和簇离子和纳米颗粒的精确测量方法。气溶胶粒径分布的测量为了测量大气气溶胶在1nm ~几微米范围内的粒径分布，对差分迁移率分析仪（DMA）、混合型冷凝核计数器（M-CNC）、法拉第杯静电计（FCE）进行了改进。特别是，新开发的粒子尺寸放大器（PSM）与传统的CNC相结合，可以在大气和低压条件下测量到3nm的纳米粒子和离子的数量浓度。此外，为了给气溶胶粒子充电，新开发了替代软x射线光电离器。为了改进气溶胶中有机碳（OC）和元素碳（EC）的测量技术，对光学技术进行了基础研究，并与采样方法进行了OC浓度的比较。为了提高碳质颗粒的测量精度，采用喷雾干燥法制备了以EC和OC为基准颗粒的标准过滤器。制备了二氧化硅/炭黑复合颗粒，并对其光学性能进行了评价。离子诱导成核纳米粒子的成核和生长实验系统由漂移管离子迁移谱仪/质谱仪和结合FCE的簇- dma组成，研究了簇离子与纳米粒子之间的关系。该系统实现了离子的质谱测量和电离辐射产生的离子和超细粒子的高分辨率迁移率光谱测量。由于气态污染物对大气气溶胶粒子的形成有重要影响，本文研究了大气主要气态污染物之一NO_2对α-射线辐照SO_2/H_2O/空气混合物中粒子形成的影响，并讨论了离子诱导成核对均匀成核的相对重要性。少

For assessment and prevention of the impact of secondary aerosol particles on atmospheric environment and human health, particle generation mechanism and methods for an accurate measurement of cluster ion and nanoparticles were investigated in this report.1. MEASUREMENT OF AEROSOL SIZE DISTRIBUTIONIn order to measure the particle size distribution of atmospheric aerosols from about 1nm to some microns, the differential mobility analyzer (DMA), mixing-type condensation nucleus counter (M-CNC), Faraday cup electrometer (FCE) were improved. Especially, combination of newly developed particle size magnifier (PSM) and conventional CNC made possible to measure number concentration of nanoparticles and ions down to 3nm in atmospheric and low pressure conditions. Moreover, in order to charge aerosol particles, alternative soft X-ray photoionizer was newly developed.2. DEVELOPMENT OF THE CARBON-CONTAINING AEROSOL MEASURING METHODFor an improvement of measuring technique for OC (organic carbon) … More and EC (elemental carbon) of aerosols, fundamental study for optical technique and comparison of OC concentrations with sampling methods were performed. For the improvement of carbonaceous particle measurement, standard filters with EC and OC reference particles were fabricated by a spray-drying method. The composite particles of SiO2/Carbon black were also prepared and the optical properties were also evaluated.3. NUCLEATION AND GROWTH OF NANO-PARTICLES BY ION-INDUCED NUCLEATIONExperimental system, which consists of a drift tube ion mobility spectrometer/mass spectrometer and a cluster-DMA combined with FCE, was developed to investigate the relationship between cluster ions and nanoparticles. This system enabled mass spectrometric measurement of ions and high-resolution mobility spectrometric measurements of ions and ultrafine particles generated by ionizing radiation. Since gaseous pollutants have significant effects on atmospheric aerosol particle formation, effects of NO_2, one of main atmospheric gaseous pollutants, on particle formation in SO_2/H_2O/air mixtures irradiated by α-ray was experimentally investigated and relative importance of ion-induced nucleation to homogeneous nucleation was discussed. Less