Atmospheric Processing of Organic Aerosols

该项目的目的是对有机表面的化学转化进行实验室研究，这些表面是对流层中颗粒有机物质的模式系统。有机气溶胶在对流层中起着重要作用，影响对流层的氧化能力和辐射平衡。它们的影响范围从城市地区的人类健康影响到与全球气候变化有关的直接和间接气溶胶强迫。这些后期的影响仍然是气候变化模拟中最大的不确定性。该项目旨在提供与大气相关的各种气相环境中有机颗粒氧化处理的定量信息。采用的实验方法结合了各种气相和表面分析技术，如低压和高压化学电离质谱，傅里叶变换红外光谱，x射线光电子光谱，原子力显微镜，接触角测量学和石英晶体微天平技术。原型有机碳表面及其混合物将作为对流层中有机气溶胶的代用品。具体项目包括研究各种对大气重要的无机和有机物质与有机碳表面在原子氧、羟基自由基、原子氯、硝酸盐自由基和臭氧的反应下的吸附和非均相反应。氧化有机碳表面与重要的无机和有机物质（如一氧化碳、二氧化氮、硝酸氯和二氧化硫）的反应将在这些氧化剂的存在下研究，使用各种有机碳原型：脂肪族、芳香族和烟灰样品及其混合物。有机碳薄膜在与各种气相大气组分（包括原子、自由基和其他不稳定物质）相互作用的过程中，其化学组成、形态和吸湿性的变化将被研究。活性有机碳表面的反应性数据将对大气模拟计算有用。本研究将有助于阐明在现实对流层条件下有机颗粒物在自由基化学中的作用。此外，这些研究项目将有助于培养和教育大气化学领域的本科生、研究生和博士后。

The objective of this project is to conduct laboratory studies of the chemical transformation of organic surfaces that are model systems for particulate organic matter in the troposphere. Organic aerosols play important roles in the troposphere, affecting its oxidative capacity and its radiative balance. Their impacts range from human health effects in urban areas to direct and indirect aerosol forcing related to global climate change. These later effects remain as some of the largest uncertainties in climate change modeling. This project is aimed at providing quantitative information on the oxidative processing of organic particles in various gas phase environments relevant to the atmosphere. The experimental approach to be employed combines various gas-phase and surface analysis techniques such as low and high pressure chemical ionization mass spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectrometry, atomic force microscopy, contact angle goniometry, and the quartz crystal microbalance technique. Prototype organic carbon surfaces and their mixtures will serve as proxies for organic aerosol in the troposphere. Specific projects to be carried out include studies of adsorption and heterogeneous reactions of various inorganic and organic species of atmospheric importance with organic carbon surfaces activated by the reactions of atomic oxygen, hydroxyl radical, atomic chlorine, nitrate radical and ozone. Reactions of oxidized organic carbon surfaces with important inorganic and organic species such as carbon monoxide, nitrogen dioxide, chlorine nitrate, and sulfur dioxide will be studied in the presence of these oxidants using various organic carbon prototypes: aliphatic, aromatic and soot samples and their mixtures. Changes in the chemical composition, morphology and hygroscopicity of organic carbon films will be investigated in the course of their interaction with various gas-phase atmospheric components including atoms and radicals and other labile species. Data on the reactivity of the activated organic carbon surfaces will be useful for atmospheric modeling calculations. This research is expected to contribute to the elucidation of the role of organic particulate matter in free radical chemistry under realistic tropospheric conditions. Furthermore, the research projects will contribute to the training and education of undergraduate, graduate and postdoctoral students in the field of the atmospheric chemistry.