Coupling of Gas-Phase Radical Oxidation Chemistry and Organic-Aerosol Formation

通过实验室实验，本项目将探索气相有机氧化化学与有机颗粒物（PM）演变之间的复杂相互作用，使用先进的仪器，包括：(1)化学电离质谱仪（CIMS），设计用于柔性，(2)高分辨率飞行时间气溶胶质谱仪（HR-AMS），用于测量50至700纳米尺寸之间的颗粒组成中与尺寸相关的非耐火部分，明确地分辨颗粒中的碳、氢、氧和氮。实验的一部分将是“传统的”二级有机气溶胶（SOA），由诸如α -蒎烯和臭氧这样的系统形成，但在一系列条件下测量过氧化物和其他活性氧。大部分实验将使用精心挑选的有机前体序列进行，这些有机前体序列旨在模拟传统SOA实验的下一代氧化产物。具体来说，SOA的形成将从二维（2D）空间中选定点的前体开始，结合挥发性和碳氧化状态，以测试有机气溶胶的质量产量和性质是否会根据该空间中的位置系统地变化。如果SOA属性确实组织在这个空间中，那将证实这种2D表示作为SOA行为的模型表示的显著简化的效用，并且这项研究的结果将提供在模型中实现这种2D框架所需的基本参数。有机气溶胶是影响气候和颗粒物健康的重要因素。在每种情况下，他们的贡献都是最不确定的。因此，该项目的结果将大大提高对影响气候的颗粒物健康影响和气溶胶-云相互作用的认识。这将为这两个领域不断发展的政策提供信息。该研究将由一名博士后、一名研究生和一名本科生进行。

Through laboratory experiments this project will probe complex interactions between gas-phase organic oxidation chemistry and the evolution of organic particulate matter (PM) making use of advanced instruments including (1) a Chemical Ionization Mass Spectrometer (CIMS) designed for flexible, highly sensitive measurement of critical radicals as well as gas-phase organic compounds including organic acids and peroxides and (2) a High-Resolution Time of Flight Aerosol Mass Spectrometer (HR-AMS) to measure the size-dependent non-refractory fraction of particle composition between 50 and 700 nanometer size, explicitly resolving carbon, hydrogen, oxygen and nitrogen in the particles. A portion of the experiments will be "traditional" secondary organic aerosol (SOA) formation from such systems as alpha-pinene plus ozone, but with measurement of peroxides and other reactive oxygen species under a range of conditions. The larger share of experiments will be carried out with several carefully selected sequences of organic precursors designed to model later-generation oxidation products of traditional SOA experiments. Specifically, SOA formation will be initiated from precursors at selected points in a 2-dimensional (2D) space combining volatility and carbon oxidation state to test whether organic aerosol mass yields and properties vary systematically based on location in this space. If SOA properties do organize in this space, that will confirm the utility of this 2D representation as a dramatic simplification for model representations of SOA behavior, and the results of this research will provide essential parameters required to implement this 2D framework in models.Organic aerosols are significant players in both climate and particulate matter health effects. In each case their contributions are among the most uncertain. Consequently, the results of this project will significantly enhance understanding of particulate matter health effects and aerosol-cloud interactions influencing climate. This will inform evolving policy in both areas. The research will be carried out by a postdoctoral associate, a graduate student, and undergraduate students.