Shining light on the sources, sinks and concentrations of singlet oxygen in the atmosphere

地球的大气层完全是氧化的，因此氧化反应决定了气相和颗粒相中大多数有机分子的命运。大气氧化剂的浓度、形态和反应性对于预测大气污染物的去向是必要的。我的长期研究计划集中在研究大气氧化剂及其氧化机制，短期重点放在大气化学背景下一种未被研究和被充分认识的氧化剂：单线态氧(1O2)，基态三重态分子氧的第一激发态。1O2是一种众所周知的激发态分子：在生物学中用于光动力疗法治疗癌症，在有机化学中用于提高氧化和环加成反应的反应性，在地表水中作为决定污染物去向的关键氧化剂。在地表水中产生1O2所需的关键成分包括增感剂、氧气和光线--所有这些都确实存在于大气中，但只有少数报告描述了大气中的1O2。我提出的研究计划是建立在我的团队最近的工作基础上的，该工作证明了在阳光充足的条件下，有机水性气雾剂作为氧气产生的敏化剂的有效性。我的团队将阐明室内和室外空气中有机气溶胶中1O2的来源(任务1)和汇(任务2)，并将开展1O2‘S气相化学(任务3)的开创性研究。任务1涉及两个室外空气项目(MSc1、MSc2)和一个室内空气项目(Phd1)，启动了一个新兴的室内空气光化学领域。任务2将阐明与大气相关的水有机气溶胶条件(PHD2)中的10O2汇。此外，任务3将演示1O2可以分配到气相中，并对气相化学反应产生前所未有的影响(博士后)。这三项任务有助于实现三个影响目标：(A)预测有机气溶胶中1O2的稳态浓度和量子产率；(B)比较1O2反应性与其他氧化剂的重要性；以及(C)首次证明1O2在气相中的存在和影响。总体而言，该研究项目将培养1名博士后、2名博士、2名硕士和10名本科生，具有很高的培训价值。事实上，它具有挑战性、创新性和影响力，但却是可行的，并以风险缓解和EDI战略为设计依据。HQP将领导项目，使用最先进的光化学技术，并参与多学科合作，作为我领导下独特的HQP培训计划的一部分。产生的原始科研成果将提供定量数据，包括浓度、速率常数、产品分布和化学机理，以改进关键空气质量成分的命运模拟。这一产出将支持政府机构、加拿大环境和气候变化部和加拿大卫生部制定监管指南。

The Earth's atmosphere is exclusively oxidizing, and consequently oxidation reactions govern the fate of most organic molecules in the gas and particle phases. The concentration, speciation and reactivity of atmospheric oxidants are necessary to predict the fate of atmospheric pollutants. My long-term research program centers on studying atmospheric oxidants as well as their oxidation mechanisms, with a short-term focus on an understudied and arguably underappreciated oxidant in the context of atmospheric chemistry: singlet oxygen (1O2) the first excited state of ground state triplet molecular oxygen. 1O2 is a well-known excited state molecule: in biology for photodynamic therapy for cancer treatment, in organic chemistry for enhanced reactivity in oxidation and cylcoaddition reactions, and in surface waters as a key oxidant in determining the fate of pollutants. The key ingredients necessary for the production of 1O2 in surface waters include a sensitizer, oxygen and light - all are indeed present in the atmosphere, yet only a handful of reports have described atmospheric 1O2. My proposed research program builds on recent work from my group demonstrating the efficacy of aqueous organic aerosols to act as sensitizers for 1O2 production under sunlit conditions. My team will elucidate the sources (Task 1) and sinks (Task 2) of 1O2 in organic aerosols in indoor and outdoor air, and will undertake groundbreaking studies on 1O2's gas phase chemistry (Task 3). Task 1 addresses two outdoor air projects (MSc1, MSc2) and an indoor air program (PhD1), kick-starting a burgeoning field of indoor air photochemistry. Task 2 will elucidate the sinks of 1O2 in atmospherically-relevant aqueous organic aerosol conditions (PhD2). Furthermore, Task 3 will demonstrate that 1O2 can partition to the gas phase and have unprecedented impact on gas-phase chemical reactions (Postdoc). These three tasks contribute to three impact goals: (A) predict 1O2 steady-state concentrations and quantum yields within organic aerosols; (B) compare the importance of 1O2 reactivity with other oxidants; and (C) demonstrate the presence and impact of 1O2 in the gas phase for the first time. Overall, this research program will train 1 postdoc, 2 PhDs, 2 MSc, and 10 undergraduates and is designed for high training value. Indeed, it is challenging, innovative, and impactful, yet feasible and designed with risk mitigation and EDI strategies. HQP will lead projects, use state-of-the-art photochemistry techniques and participate in multidisciplinary collaborations as part of a unique HQP training program under my leadership. The original scientific research output generated will provide quantitative data including concentrations, rate constants, product distributions and chemical mechanisms to improve fate modelling of key air quality components. This output will support the development of regulatory guidelines by government agencies, Environment and Climate Change Canada and Health Canada.