Kinetics and Photochemistry of Atmospheric Aldehyde Reactions

9610285朱这个项目的主要目标是确定大气中乙醛反应的动力学和它们的光化学。醛是影响烟雾过程的光化学反应的关键参与者；它们的光解离是对流层光化学中自由基和有机气溶胶的主要来源。尽管乙醛光解在对流层化学中很重要，但无论是在大气条件下还是在可以很容易推断为大气条件的条件下，对乙醛光解产物通道和量子产率的研究都很少。自由基，如甲酰自由基，在大气中很容易转化为氢过氧基和羟基自由基，参与光化学氧化过程。在本项目中，将对含五个或更多碳原子的醛、芳香醛和二羰基的光解进行研究。将表征光解产物的通道和量子产率，以及它们对光解波长的依赖关系。对于同系列的醛，将提取烷基侧链结构与光解量子产率之间的关系。实验研究将使用脉冲激光光解和一种灵敏的光学吸收技术--腔衰荡光谱来进行。除了光解研究外，还将阐明醛形成反应的动力学和机理，如甲氧基与分子氧的反应。

9610285 Zhu The primary objective of this project is to determine the kinetics of atmospheric aldehyde reactions and their photochemistry. Aldehydes are key participants in photochemical reactions affecting smog processes; their photodissociation represents a major source of free radicals and organic aerosols for tropospheric photochemistry. Despite the importance of aldehyde photolysis in the chemistry of the troposphere, few studies of aldehyde photolysis product channels and quantum yields have been carried out either under atmospheric conditions or under conditions that can be readily extrapolated to those of the atmosphere. Free radicals, such as formyl radicals, are readily converted in the atmosphere to hydroperoxyl and hydroxyl radicals, which participate in photochemical oxidation processes. In this project, studies of the photolysis of aldehydes with five carbon atoms or more, aromatic aldehydes, and dicarbonyls, will be carried out. The photolysis product channels and quantum yields will be characterized, as well as their dependence on photodissociation wavelengths. The relationship between the structure of alkyl side chains and photolysis quantum yields will be extracted for homologous series of aldehydes. The experimental studies will be carried out using pulsed laser photolysis coupled with a sensitive optical absorption technique, cavity ring-down spectroscopy. In addition to the photolysis studies, the kinetics and mechanisms of aldehyde formation reactions, such as the reaction of the methoxy radical with molecular oxygen, will be elucidated.