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.

次生有机气溶胶（SOA）有助于直接和间接地在气候上辐射强迫，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，以及（2）研究涉及云处理过程中涉及水溶性SOA的水化学水化学。模型SOA将在烟雾室中产生，并在各种状态下暴露于模拟太阳辐射中：低相对湿度（RH）的干SOA，高RH的水合SOA，SOA在与云和雾有关的浓度下溶于水中，而SOA则在冷冻水提取物中溶于水中。 SOA的分子组成将以高分辨率质谱和其他分析方法为特征，并在暴露于模拟太阳辐射之前和之后。在一组平行的实验中，将使用PI实验室中开发的独特光谱和质谱工具来测量SOA的光解离动作光谱。对于嵌入SOA样材料中的几种代表性的羰基化合物，将确定光解的绝对光解离量子产率和光解的详细机制。该信息将用于估计大气SOA颗粒内部以及含有溶解的SOA的云液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理解。结果还将有助于研究相关学科（1）空气中老化有机物的健康影响以及（2）涉及其他媒体中太阳辐射与复杂有机混合物之间相互作用的过程（例如，有机聚合物和涂料的光降解，土壤有机物的光化学，光降解，溶解有机物和水纯化的光降解）。该项目将支持两名研究生，并将通过大会上的演讲和同行评审的出版物广泛传播发现。首席研究人员和学生还将通过正在进行的教育和外展活动向公众传达基础研究的重要性和兴奋，包括为期两周的长期夏季研讨会，为高中科学教师和演讲，实验室旅行和教育研讨会提供动手实验室培训。