Spectroscopic Studies of Homogeneous Precursors to Atmospheric Acids and Aerosols

新建造的脉冲喷嘴傅里叶变换微波光谱仪将用于确定各种气体物种的结构、偶极矩和反应能量，这些气体物种是某些大气气溶胶和酸的前驱物质。将特别强调三氧化硫(SO3)的加合物，它是大气中硫酸(H_2SO_4)的直接前体。其他研究将集中在涉及水蒸气、三氧化硫、氨、二氧化硫、硫酸、氮氧化物和硝酸的络合物。来自这些光谱研究的数据将提供关于产生硫酸和硝酸气溶胶的化学机制的新的分子水平的细节。由于气溶胶影响地球的反照率和降水模式，这项研究将影响我们对气候的理解。许多以研究为目标的加合物预计涉及介于范德华和共价之间的成键力。因此，这项研究将探索非传统成键在假设的大气重要性过程中所涉及的络合物中的作用。最初项目的扩展将包括研究自由基中间体和代表均相成核过程中二聚体以外的下一步的选定的三级团簇。

A newly constructed, pulsed-nozzle Fourier transform microwave spectrometer will be used to determine the structures, dipole moments, and reaction energetics of a variety of gaseous species that are precursors to certain atmospheric aerosols and acids. Particular emphasis will be placed on adducts of sulfur trioxide (SO3), which is the immediate precursor to sulfuric acid (H2SO4) in the atmosphere. Additional studies will focus on complexes involving water vapor, sulfur trioxide, ammonia, sulfur dioxide, sulfuric acid, nitrogen oxides, and nitric acid. The data from these spectroscopic investigations will provide new molecular-level detail about the chemical mechanisms that produce sulfuric acid and nitric acid aerosols. Because aerosols influence the earth's albedo and precipitation patterns, this research will impact our understanding of climate. Many of the adducts targeted for study are expected to involve bonding forces that are intermediate between van der Waals and covalent. Consequently, this research will explore the role of unconventional bonding in complexes involved in postulated processes of atmospheric importance. Extensions of the initial project will include studies of radical intermediates and selected tertiary clusters that represent the next step beyond dimers in the homogeneous nucleation process.