Photosensitization: A novel pathway to SOA generation and property change in tropospheric particles

光敏化：对流层粒子 SOA 生成和性质变化的新途径

• 批准号: 316976724
• 负责人: Professor Dr. Hartmut Herrmann
• 金额: --
• 依托单位: Leibniz-Institut für Troposphärenforschung e.V. (TROPOS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/316976724?language=en
• 关键词: Photosensitization; novel; pathway; SOA; generation

Tropospheric aerosol particles have often been described and represented in models in a simplistic way considering them as non-volatile and chemically inert. Such assumptions were recently been challenged by frontline research, according to which volatile organic compounds (VOCs) and secondary organic aerosols (SOA) form a system that evolves in the atmosphere by chemical and dynamical processing. A current key issue concern in the physico-chemistry of atmospheric organic particulate matter is that the models based on available parameterizations from laboratory studies strongly underestimate SOA and do not adequately account for particle growth as it is observed in the atmosphere. The difference between ambient and modeled SOA concentrations clearly suggests that other significant SOA sources have not yet been identified and characterized. Important efforts were consequently made to explain and close this gap. For instance, it was shown that gaseous glyoxal, which was previously considered as too volatile to noticeably partition into the particulate phase, could significantly contribute to SOA mass through multiphase chemistry. Glyoxal, and other small dicarbonyls are formed in large amounts during VOC oxidation. Condensed phase sinks for these gases are indeed able to explain an important part of the missing SOA mass in models, often addressed as aqSOA. However, observations imply that there are still large uncertainties about the tropospheric SOA formation - conventional aqSOA apparently cannot explain all missing SOA. Furthermore, multiphase processes have also been shown to produce light absorbing compounds in the particle phase. The formation of such light absorbing species could induce new photochemical processes within the aerosol particles and/or at the gas/particle interface. A significant body of literature on photo-induced charge or energy transfer in organic molecules from other fields of science exists. Such organic molecules are aromatics, substituted carbonyls and/or nitrogen containing compounds - all ubiquitous in tropospheric aerosols. Therefore, while aquatic photochemistry has recognized several of these processes that accelerate degradation of dissolved organic matter, only little is known about such processes in/on atmospheric particles. Therefore, within PHOTOSOA it is suggested to study photosensitization in the troposphere as it may play a significant role in SOA formation and ageing. Such photosensitization may introduce new chemical pathways so far unconsidered impacting both the atmospheric chemical composition and can thus contribute to close the current SOA underestimation. This project aims at tackling such issues by combining different laboratory based activities focusing on the chemistry of triplet state compounds of relevant photosensitizers, in various phases and their role in SOA processing. Clearly, frontline basic research studies on such processes are needed in order to be able to assess their importance.

对流层气雾剂颗粒经常以一种简单的方式描述并以一种非易失性和化学惰性为例。最近，一线研究对这种假设进行了挑战，根据这些研究，挥发性有机化合物（VOC）和次级有机气溶胶（SOA）形成了一种系统，该系统通过化学和动力学处理在大气中演变而成。当前的关键问题问题是大气有机颗粒物质物质的物理化学化学，是基于实验室研究的可用参数化的模型强烈低估了SOA，并且不能充分考虑到在大气中观察到的颗粒生长。环境和建模的SOA浓度之间的差异清楚地表明，尚未确定和表征其他重要的SOA源。因此，为解释和缩小这一差距而做出了重要的努力。例如，已经表明，以前认为过于挥发而无法明确分配到颗粒相中的气态乙二醇可能会通过多相化学显着促进SOA质量。在VOC氧化过程中，大量形成了乙二醛和其他小型双骨。这些气体的冷凝相水槽确实能够解释模型中缺失的SOA质量的重要部分，通常被称为AQSOA。但是，观察结果表明，对流层SOA形成仍然存在很大的不确定性 - 常规AQSOA显然无法解释所有缺失的SOA。此外，还显示多相过程在颗粒相中会产生光吸收化合物。这种光吸收物种的形成可以诱导气溶胶颗粒和/或气体/粒子界面内的新光化学过程。关于来自其他科学领域的有机分子中光诱导的电荷或能量转移的大量文献存在。这样的有机分子是芳香族剂，取代的羰基和/或含氮的化合物 - 所有无处不在的对流层气溶胶。因此，尽管水生光化学已经识别出加速溶解有机物降解的几个过程，但对大气颗粒中/上的此类过程知之甚少。因此，在Photosoa中，建议研究对流层中的光敏化，因为它可能在SOA形成和衰老中起重要作用。这种光敏化可能会引入到迄今未经考虑的新化学途径，从而影响大气化学成分，从而有助于关闭当前的SOA低估。该项目旨在通过将不同的基于实验室的活动结合到相关光敏剂的三胞胎状态化学，各个阶段及其在SOA处理中的作用，以解决此类问题。显然，需要对此类过程的一线基础研究，以便能够评估其重要性。