Collaborative Research: RUI: IRES - Track I: Brown Carbon Aerosol Formation by Photooxidation of Phenolic Compounds in Nanodroplets

这个IRES项目为来自圣地亚哥大学和哈维穆德学院的4-6名本科生研究人员提供了8-10周的时间，研究大气中酚类化合物的水光氧化形成棕色碳。为期四周的研究将在大学现场进行。巴黎东部？Cr吗?在这里，本科生研究人员将与他们的国际导师密切合作，利用先进的光谱方法进行一系列CESAM气溶胶室实验。从法国回国后，本科研究团队将专注于实验室数据的分析、解释和展示，同时继续通过视频会议与国际导师进行互动。每位参与者将参与该项目至少一个学期之前和两个学期之后，前往他们的美国校园进行培训和进一步的实验。总共有15名本科生将参加这个为期3年的国际项目，他们将在法国科学家的指导下获得先进研究工具的实践经验。这个IRES项目的重点是大气化学，将有助于更好地了解清洁空气和全球变暖。在生物质燃烧和人为芳香族前体氧化过程中产生的酚类化合物被认为是在云滴中氧化时棕色碳气溶胶的重要来源，特别是在铁（来自灰尘）或氮氧化物（来自燃烧污染）存在的情况下。然而，酚类化合物的多相反应主要是在散装水溶液中进行的，而不是在更现实的纳米液滴中进行的，在纳米液滴中，光漂白会变成光褐变，反应性往往会加速，特别是对表面活性低聚的物质。因此，研究人员将在巴黎CESAM实验室的纳米液滴“云模拟”光氧化实验中研究酚类前体物质形成的棕色二次有机气溶胶（SOA），表征云事件发生之前、期间和之后气溶胶颗粒的化学和光学变化。当反应物在压力、温度和rh控制的腔室中与种子气溶胶、水滴和模拟阳光相互作用时，将通过CAPS-ssa和水溶性OA的紫外/可见光谱来监测颗粒褐变。粒子相化学将通过气溶胶质谱（ACSM-TOF）进行监测，粒子的吸收和放气将通过高分辨率的PTR-MS和气相物种的长路径FTIR监测来检测。该项目将为15名不同的美国本科生提供最先进的云室设施的国际研究经验，作为每位参与者三个学期研究经验的中心。项目活动将增进对棕色SOA重要来源的了解，从而使这种污染物及其对人类健康和气候造成的不利影响能够以更具成本效益的方式最小化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This IRES project provides experiences for 4-6 undergraduate researchers from the University of San Diego and Harvey Mudd College to spend 8-10 weeks researching brown carbon formation by aqueous photooxidation of atmospheric phenolic compounds. Four weeks of research will be conducted onsite at Universit? Paris Est ? Cr?teil (UPEC), where the cohort of undergraduate researchers will closely collaborate with their international mentors on a series of CESAM aerosol chamber experiments utilizing advance spectroscopic methods. After returning from France, the undergraduate research team will focus on the workup, interpretation, and presentation of chamber data, while continuing to interact with international mentors via video conferencing. Each participant will be involved in the project for at least one semester prior and two semesters subsequent to travel for training and further experimentation at their U.S. campuses. In total, 15 undergraduates over 3 years will participate in this international project and will be mentored by French scientists while gaining hands-on experience with advanced research tools. This IRES project is focused on atmospheric chemistry and will contribute to the better understanding of clean air and global warming.Phenolic compounds, which are produced during biomass burning and from the oxidation of anthropogenic aromatic precursors, are believed to be significant sources of brown carbon aerosol when oxidized in cloud droplets, especially in the presence of iron (from dust) or nitrogen oxides (from combustion pollution). However, multi-phase reactions of phenolic compounds have been studied mainly in bulk aqueous solutions rather than in more realistic nanodroplets, where photobleaching can become photobrowning and where reactivity is often accelerated, especially for surface-active oligomerizing species. The researchers will therefore study brown secondary organic aerosol (SOA) formation by phenolic precursor species in nanodroplet "cloud simulation" photooxidation experiments at the CESAM chamber in Paris, characterizing chemical and optical changes in aerosol particles before, during, and after cloud events. Particle browning will be monitored by CAPS-ssa and UV/visible spectroscopy of water-soluble OA as the reactants interact with seed aerosol, water droplets, and simulated sunlight in the pressure, temperature, and RH-controlled chamber. Particle-phase chemistry will be monitored by aerosol mass spectrometry (ACSM-TOF), and particle uptake and outgassing will be detected by high-resolution PTR-MS and long-path FTIR monitoring of gas- phase species. This project will provide 15 diverse U.S. undergraduates with international research experiences at a state-of-the-art cloud chamber facility as the center of a 3-semester research experience for each participant. Project activities will increase understanding of important sources of brown SOA, which will in turn allow this pollutant, and the adverse effects on human health and climate that it causes, to be minimized in a more cost-effective manner.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.