Towards a Molecular Understanding of Atmospheric Nucleation: Reactions of Amines with Sulfuric Acid Clusters

几个新的仪器将被用来探索这样的假设，即在大气边界层中观察到的高气溶胶成核率主要是由于胺与硫酸分子簇的反应。团簇化学电离质谱仪(CLUSTER CIMS)测量成核过程中产生的中性分子团簇的浓度和质量。二甘醇凝聚粒子计数器(DEG CPC)用作气溶胶迁移率光谱仪的探测器时，可以测量尺寸为1纳米的粒子迁移率分布。与集群CIMS的并行测量允许定义小至一个分子的完整尺寸谱。常压质子转移质谱仪(AmpMS)可以实时测量胺。计算化学将补充实验室成核实验和宾夕法尼亚州匹兹堡大气中的测量，帮助阐明在星团CIMS中发生的化学电离过程，以及负责在大气中形成稳定核的热力学和动力学过程。在大气中通过成核形成新粒子影响云核的浓度，从而影响地球的反照率。云反照率效应中的不确定性是气候模型中不确定性的最大来源。考虑到新粒子的产生是这种不确定性的一个来源。该项目将支持两名研究生和一名博士后学者，并为本科生提供研究经验机会。外联活动将包括向明尼苏达州在校学生介绍情况和进行实验室练习，与化学系妇女参与科学和工程分会合作，参加科学营活动，以及努力提高发展中国家对炉灶排放的木烟对健康影响的认识。

Several new instruments will be used to explore the hypothesis that the high aerosol nucleation rates observed in the atmospheric boundary layer are primarily due to the reaction of amines with sulfuric acid molecular clusters. The cluster chemical ionization mass spectrometer (Cluster CIMS) measures the concentrations and masses of neutral molecular clusters produced by nucleation. The diethylene glycol condensation particle counter (DEG CPC), when used as the detector for an aerosol mobility spectrometer, allows measurements of particle mobility distributions down to 1 nanometer size. Parallel measurements with the Cluster CIMS allow definition of the complete spectrum of sizes down to one molecule. The ambient pressure proton transfer mass spectrometer (AmpMS) allows real-time measurements of amines. Computational chemistry will complement laboratory nucleation experiments and measurements in the atmosphere of Pittsburgh, PA by helping to elucidate processes that occur during chemical ionization in the Cluster CIMS as well as the thermodynamic and kinetic processes responsible for the formation of stable nuclei in the atmosphere.The formation of new particles by nucleation in the atmosphere affects concentrations of cloud nuclei and, therefore, the earth's albedo. Uncertainties in the cloud albedo effect are the largest source of uncertainty in climate models. Accounting for new particle production is one source of this uncertainty. This project will support two graduate students and a post-doctoral scholar as well as offer research experience opportunities to undergraduate students. Outreach activities will include presentations to and laboratory exercises with Minnesota school students, involvement in science camp efforts in collaboration with the Department of Chemistry's chapter of Women in Science and Engineering, and efforts to increase awareness of the health impacts of wood smoke emissions from cook stoves in developing countries.