Photochemistry in Organic Aerosols

有机气溶胶中的光化学

• 批准号: 1227579
• 负责人: Sergey Nizkorodov
• 金额: $ 54.76万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1227579&HistoricalAwards=false
• 关键词: Photochemistry; Organic; Aerosols

Secondary Organic Aerosols (SOA) contribute to radiative forcing on climate both directly and indirectly and also affect urban air quality. The main goals of this award are: (1) To investigate the mechanism and significance of direct and indirect photolysis processes occurring in SOA and (2) to investigate aqueous photochemistry involving water-soluble SOA during cloud-processing. Model SOA will be generated in a smog chamber and exposed to simulated solar radiation in various states: Dry SOA at low relative humidity (RH), hydrated SOA at high RH, SOA dissolved in water at concentrations relevant to clouds and fogs, and SOA in frozen aqueous extracts. The molecular composition of SOA will characterized by high-resolution mass spectrometry and other analytical methods before and after exposure to the simulated solar radiation. In a parallel set of experiments, photodissociation action spectra of SOA will be measured using unique spectroscopic and mass-spectrometric tools developed in the PI's laboratory. The absolute photodissociation quantum yields and detailed mechanisms of photolysis will be determined for several representative carbonyl compounds embedded in SOA-like materials. This information will be used to estimate rates of photochemical reactions occurring inside atmospheric SOA particles and inside cloud droplets containing dissolved SOA.This project will provide molecular-level understanding of photochemical reactions in SOA and in aqueous solutions of SOA material. Results will also contribute to related disciplines investigating (1) health effects of aged organic matter in air and (2) processes involving interactions between solar radiation and complex organic mixtures in other media (e.g., photodegradation of organic polymers and coatings, photochemistry of soil organics, photodegradation of dissolved organic matter, and water purification). The project will support two graduate students and findings will be widely disseminated through presentations at major conferences and peer-reviewed publications. The principal investigator and student will also communicating the importance and excitement of fundamental research to the general public through ongoing educational and outreach activities including a two-week long summer workshop that provides hands-on laboratory training for high school science teachers and presentations, lab tours, and educational seminars for the general public.

二次有机气溶胶（SOA）对气候的辐射强迫有直接和间接的贡献，并影响城市空气质量。该奖项的主要目标是：（1）研究SOA中发生的直接和间接光解过程的机制和意义;（2）研究云处理过程中涉及水溶性SOA的水溶液光化学。模型SOA将在烟雾室中生成，并暴露于各种状态的模拟太阳辐射：低相对湿度（RH）下的干燥SOA，高RH下的水合SOA，以与云和雾相关的浓度溶解在水中的SOA，以及冷冻水提取物中的SOA。利用高分辨质谱等分析手段，对模拟太阳辐射前后SOA的分子组成进行表征。在一组平行的实验中，SOA的光解离作用光谱将使用PI实验室开发的独特的光谱和质谱工具进行测量。绝对光解量子产率和详细的光解机制将被确定为几个代表性的羰基化合物嵌入SOA类材料。这些信息将用于估计大气中SOA颗粒和含有溶解的SOA的云滴内发生的光化学反应的速率。该项目将提供对SOA和SOA材料水溶液中光化学反应的分子水平的理解。研究结果还将有助于相关学科的调查（1）空气中老化有机物的健康影响和（2）涉及太阳辐射和其他介质中复杂有机混合物之间相互作用的过程（例如，有机聚合物和涂层的光降解、土壤有机物的光化学、溶解有机物的光降解以及水净化）。该项目将资助两名研究生，研究结果将通过在主要会议上的演讲和同行评审的出版物广泛传播。主要研究者和学生还将通过正在进行的教育和推广活动，包括为期两周的夏季研讨会，为高中科学教师提供实践实验室培训，并为公众提供演示，实验室图尔斯和教育研讨会，向公众传达基础研究的重要性和兴奋。