Acquisition of Instrumentation for Quantification of Organic Compounds Responsible for Aerosol Formation

该主要研究仪器奖支持购买和开发最先进的气溶胶研究仪器。它将能够同时表征二次气溶胶在实验室环境中形成和演变时发生在气相和凝聚相中的化学反应。将购买气相色谱-飞行时间质谱（GC-TOF-MS）台式仪器，以提供碳氢化合物和含氧挥发性有机化合物的快速化学分析。三重四极杆质谱仪将与离子化学电离前端（TSQ-SICIMS）耦合，用于实时分析短寿命活性化合物。制备性毛细管气液色谱（PCGC）仪器将用于分离大量的挥发性有机化合物，以便随后使用多种仪器进行分析。最后，将开发一个气溶胶捕集器/浓缩器，作为质谱仪的前端，用于快速分析气溶胶的化学成分。使用这些新仪器进行的研究将对地球大气中产生有机气溶胶的机制提供更好的约束。该仪器与加州理工学院环境室现有的气溶胶仪器相结合，将在解决以下问题方面取得重大进展：-气相中低挥发性氧化产物的形成对有机气溶胶的预算有多重要，以及这种化学反应如何影响大气气溶胶的物理性质和环境效应？-在确定气溶胶的化学成分时，气溶胶相反应相对于气相氧化之后的气体到颗粒的吸收有多重要？-气溶胶产生过程的分子机制和动力学是什么？-导致气溶胶形成的最重要的化学物质是什么（有机酸、低聚物/聚合物等），它们的物理化学性质是什么（官能团、分子质量、稳定性、挥发性、溶解度、吸湿性、光学吸收等）？-在大气氧化剂的存在下，气相和气溶胶成分是如何演变的？准确描述导致地球大气中气溶胶形成的化学过程对于理解生物圈和气候的相互作用以及设计适当的空气质量改善策略至关重要。这种气溶胶通过对人类和动物健康的有害影响以及对城市和区域能见度的影响，在环境中发挥着重要作用。大气气溶胶的化学和物理性质也决定了它的光散射和吸收特性，这些特性在一定程度上控制着地球的辐射场和气候。最后，气溶胶的吸湿性在控制气溶胶粒子形成云滴的效率方面起着重要作用。通过该奖项获得的仪器将大大提高对控制大气有机气溶胶化学组成的有机化学性质的理解。新的仪器将加强研究生和本科生化学家、地球化学家、物理学家和他们的教师导师之间新的跨学科合作。

This Major Research Instrumentation award supports the acquisition and development of state-of-the art instrumentation for aerosol research. It will enable simultaneous characterization of the chemistry occurring in the gas and condensed phases as secondary aerosol forms and evolves in a laboratory setting. A benchtop instrument for gas chromatography - time-of-flight mass spectrometry (GC-TOF-MS) will be purchased to provide rapid chemical analysis of hydrocarbons and oxygenated volatile organic compounds. A triple quadrupole mass spectrometer will be coupled to an ion chemical ionization front end (TSQ-SICIMS) for real-time analysis of short-lived, reactive compounds. A preparative capillary gas-liquid chromatography (PCGC) instrument will be used to isolate larger quantities of volatile organic compounds for subsequent analysis with a broad array of instruments. Finally, an aerosol trap / concentrator will be developed for use as a front end to the mass spectrometers for rapid analysis of the chemical composition of aerosol.Studies using these new instruments will provide improved constraints on the mechanisms responsible for production of organic aerosol in Earth's atmosphere. This instrumentation, in combination with the aerosol instrumentation currently available on the Caltech environmental chamber, will enable significant progress in addressing questions such as: - How important is the formation of low volatility oxidation products in the gas phase to the budget of organic aerosol and how does this chemistry influence the physical properties and environmental effects of atmospheric aerosols?- How important are aerosol-phase reactions relative to gas-phase oxidation followed by gas-to-particle uptake for determining the chemical composition of the aerosol?- What are the molecular mechanisms and kinetics of the processes involved in aerosol production?- What are the most important chemicals leading to aerosol formation (organic acids, oligomers/polymers, etc.) and what are their physicochemical properties (functional groups, molecular mass, stability, volatility, solubility, hygroscopicity, optical absorption, etc.)?- How do the gas phase and the aerosol composition evolve in the presence of atmospheric oxidants?Accurate characterization of the chemistry leading to the formation of aerosol in Earth's atmosphere is essential for understanding the interactions of the biosphere and climate as well as for designing appropriate air quality improvement strategies. This aerosol plays a major role in the environment through its deleterious influence on human and animal health and through its impact on visibility in both urban and regional areas. The chemical and physical nature of atmospheric aerosol also determines its light scattering and absorption properties that, in part, control the Earth's radiation field and climate. Finally, the hygroscopicity of the aerosol plays an important role in controlling how efficient an aerosol particle will be for formation of cloud droplets. The instrumentation acquired through this award will provide substantially improved understanding of the nature of the organic chemistry that controls the chemical makeup of atmospheric organic aerosol. The new instrumentation will enhance new and interdisciplinary collaborations of graduate and undergraduate chemists, geochemists, and physicists and their faculty mentors.