Studies of Atmospheric Gas-to-Particle Conversion

本研究项目将对生物生烃系统的大气化学和气固转化现象进行研究。这项研究的目的是阐明关键生物碳氢化合物的气相光氧化途径，识别这些碳氢化合物的气溶胶形成能力，进一步了解大气有机系统中的气固转化现象，并评价成核理论对大气物种的适用性。室外烟雾室实验将使用异戊二烯/NOx和β-蒎烯/NOx混合物在不同的浓度水平范围内进行。测量的数量包括碳氢化合物、臭氧、NO、NO2的浓度，用差示迁移率分析仪、光学颗粒计数器和气雾仪测量的气溶胶粒度分布，以及用GC/MS和FTIR分析的气溶胶分子组成。将研究已确定的气溶胶物种与水作为单组分或双组分成核的情况。关于发展成核动力学理论的理论工作将继续进行。对实验数据的分析将涉及对气相化学反应机理的描述，包括可凝聚物种的产生，这些物种的成核，无论是大分子的还是二元的，以及这些物种和额外的物种向颗粒的扩散。

The atmospheric chemistry and gas-to-particle conversion phenomena of biogenic hydrocarbon systems will be investigated in this research project. The goals of the research are to elucidate the gas-phase photooxidation pathways of key biogenic hydrocarbons, to identify the aerosol-forming capability of these hydrocarbons, to further understanding of gas-to-particle conversion phenomena in atmospheric organic systems, and to evaluate the applicability of nucleation theories to atmospheric species. Outdoor smog chamber experiments will be conducted with isoprene/NOx and beta pinene/NOx mixture over a spectrum of concentration levels. Quantities to be measured include hydrocarbon, O3, NO, NO2 concentrations, aerosol size distributions by differential mobility analyzer, optical particle counter and epiphianiometer, and aerosol molecular composition by GC/MS and FTIR analyses. Aerosol species identified will be studied for nucleation either as single component or binary, with water. Theoretical work will continue on the development of a kinetic theory of nucleation. Analysis of the experimental data will involve a description of gas-phase chemical reaction mechanisms, including the generation of condensable species, the nucleation of these species, either homomolecular or binary, and the diffusion of these and additional species to particles.