Atmospheric Ozone Chemistry

大气中的臭氧在对流层似乎在增加（它在对流层造成空气污染并直接对植物有害），但在平流层却在减少（它在平流层保护地球表面免受有害的太阳紫外线辐射）。我们早就认识到臭氧在低层和中层大气中所起的关键作用，但直到最近才开始了解控制臭氧形成和破坏的循环的某些方面。本提案涉及一系列旨在确定涉及臭氧化学的关键动力学和光化学参数的实验项目。后者包括300 nm以上（对流层中很重要）和250 nm以下（平流层上层很重要）的电子激发氧原子在0.3光解后的产率。还将研究高度不稳定的原子产物与H.20和HCI的反应性，以期阐明这种反应发生的详细机制。这些研究对于全面了解激光探测大气氢氧根的光化学干扰至关重要。诱导 荧光。还计划对off进行改进。对角LIF技术用于OH和0.2的检测，后者包括激发态预解离寿命的直接测量（在皮秒时间尺度上），这对观测光谱的量化至关重要。此外，我们将继续我们最初的努力，将超级计算机上的分子模拟技术应用于不方便在实验室中研究的反应的机理检查。总之，这些实验室和计算机实验将支持现场技术和数学模型的发展，用于整合我们对臭氧在日益受到干扰的大气中的行为的理解。

Atmospheric ozone seems to be increasing in the troposphere (where it causes air pollution and is directly toxic to plants), but decreasing in the stratosphere (where it shields the Earth's surface from harmful solar ultraviolet radiation). We have long recognized the critical role played by ozone in the lower and middle atmosphere, but only recently have come to understand some aspects of the cycles that control its formation and destruction. This proposal deals with a series of experimental projects designed to determine critical kinetic and photochemical parameters involving ozone chemistry. The latter include the yield of electronically excited oxygen atoms following 0.3 photolysis above 300 nm (of importance in the troposphere) and below 250 nm (vital in the upper stratosphere). Reactivity of the highly labile atomic product with H.20 and HCI will also be examined, with a view toward elucidating the detailed mechanisms by which such reactions occur. Such studies will be vital in developing a comprehensive understanding of photochemical interferences in proposed detection schemes of atmospheric OH by laser.induced fluorescence. Also planned are refinement of off.diagonal LIF techniques for detection of OH and O.2, the latter including direct measurements of excited state predissociation lifetimes (on a picosecond time scale|) critical to the quantification of observed spectra. In addition, we shall continue our initial efforts in which the techniques of molecular simulation on a supercomputer are applied to the mechanistic examination of reactions not conveniently studied in the laboratory. Together, these laboratory and computer experiments will support the development of field techniques and mathematical models used to integrate our understanding of ozone's behavior in the increasingly perturbed atmosphere.