Ozone Reaction Rates Critical to Mesospheric Data Interpretation

中层排放的测量依赖于动力学解释，以确定高层大气的关键光化学反应物。推导氢（H）浓度的最大不确定性是产生Meinel带发射并去除O3（臭氧）的重要放热反应H + O3中的~50%误差。 减少这种不确定性也将增加在模拟比较和解释对大气变化和动态的反应方面的信心。由于该反应的推荐速率常数仅依赖于两项较早的温度依赖性研究，因此本研究在较宽的温度范围（140-400 K）内使用激光光解/激光诱导荧光（LIF）测量。光解的O3/H2或HCl混合物将与时间相关的LIF诊断H反应物消失和OH（v=9）的产品外观。新的测量应消除不可接受的大误差项。关键物种，如H，O和O3的建模也受到这种速率常数的不确定性和特定速率常数在检查模型与数据的不一致所提出的问题。与上述H + O3反应相关的第二个问题涉及O3浓度和长期存在的O3模型不足问题。因此，根据新的理论信息，研究人员将研究第二个关键的O3反应速率常数，它的形成O + O2重组。最近的量子轨道计算表明存在长寿命的共振碰撞，这应该能够在与大气有关的非常低的压力下产生意想不到的，增加的速率常数，但在实验室中无法访问。这项工作将始终采用主方程计算的动力学速率理论的量子结果映射这种压力依赖性及其不确定性和影响。一个新的概念，基本速率理论的重要性将被引入小分子重组，即罕见的长寿命碰撞共振在非常低的压力反应的作用。这些条件很难用实验来探测。大气模型的两个重要方面以及由此得出的结论将得到改进。该项目还将有助于博士后研究员和暑期本科生的培训和研究经验。改进控制高层大气臭氧化学的两个关键速率常数将产生更广泛的影响，因为这一区域的建模得到了改进。将在大气条件下解决两个具体问题。研究结果将有利于大气建模者、动力学家和分析高空气象数据的人，包括当前卫星任务的数据。从排放数据得出的H原子浓度将更加精确。

Measurements of mesospheric emissions rely on kinetic interpretations to determine the key photochemical reactants of the upper atmosphere. The largest uncertainty in deriving hydrogen (H) concentrations is the ~50% error in the important heat release reaction H + O3 that produces the Meinel band emissions and removes O3 (ozone). Reducing this uncertainty will also increase confidence in modeling comparisons and interpreting responses to atmospheric variations and dynamics. Because the recommended rate constant for this reaction relies on just two older temperature-dependent studies, this research makes use of laser photolysis/laser-induced fluorescence (LIF) measurements over a wide temperature range (140-400 K). Photolysis of O3/H2 or HCl mixtures will be coupled with time-dependent LIF diagnostics for H reactant disappearance and OH (v=9) product appearance. The new measurements should remove the unacceptably large error term. Modeling of key species such as H, O, and O3 is also affected by such rate constant uncertainties and by issues raised about specific rate constants in examining model disagreements with data. A second issue related to the H + O3 reaction above concerns the O3 concentration and the longstanding O3 model deficit problem. Thus, in the light of new theoretical information, the investigators will examine a second critical O3 reaction rate constant, its formation by O + O2 recombination. Recent quantum trajectory calculations show the presence of long-lived resonant collisions, which should be capable of producing unexpected, increased rate constants at the very low pressures pertaining to the atmosphere but not accessed in the laboratory. This work will consistently incorporate the quantum results into kinetic rate theory using master equation calculations to map this pressure dependence and its uncertainty and implications. The importance of a new concept to basic rate theory will be introduced for small molecule recombinations, namely the role of rare long-lived collisional resonances in very low-pressure reactions. These conditions are very difficult to probe experimentally. Two important aspects of atmospheric models, and conclusions drawn as a result, will be improved. The project will also contribute to the training and research experiences of a postdoctoral fellow and summer undergraduate students. Improving two key rate constants controlling the ozone chemistry of the upper atmosphere will have broader impacts as a result of the improved modeling of this region that results. Two specific problems will be addressed at atmospheric conditions. The results will benefit atmospheric modelers, kineticists, and those analyzing aeronomy data, including data from current satellite missions. Concentrations of H atoms derived from emissions data will be much more precise.