Models for Atmospheric Organic Nitrate-Forming Reactions

大气有机硝酸盐形成反应模型

• 批准号: 0804255
• 负责人: John Barker
• 金额: $ 55.02万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0804255&HistoricalAwards=false
• 关键词: Models; Atmospheric; Organic; Nitrate; Forming

The goal of this work is to determine the fundamental dynamics of key organic nitrate-forming reactions and develop predictive models of this chemistry. It is hypothesized that the master equation (ME) approach for this class of reactions suffers from a failure of Rice-Ramsperger-Kassel-Marcus (RRKM) theory because of slow intramolecular vibrational energy redistribution (IVR). Quasi-classical trajectory (QCT) calculations will be used to assess the importance of slow IVR in the reaction system consisting of peroxy radicals (RO2) with nitric oxide (NO) to form alkoxy radicals (RO) or alkyl nitrates (RONO2). When feasible, analytical potential energy surfaces will be constructed; direct dynamics with a parameterized semiempirical quantum theory like NDDO-SRP (neglect of diatomic differential overlap - specific reaction parameters) will also be used to calculate the potential and its gradients. Both approaches will be evaluated using high level electronic structure calculations. Temperature and pressure-dependent yields of nitrates from nitrate radical (NO3) + alkene reactions of primary and secondary alkenes as a function of carbon chain length will also be calculated.The results will enable other researchers to develop accurate atmospheric chemistry models to predict atmospheric nitrate yields as a function of temperature, pressure, and the identity of the RO2 radical or alkene. All parameterizations, ME source codes, and models will be made freely available on the internet. Insights into non-RRKM kinetics will be applicable to the study of other non-equilibrium systems, such as in combustion. Students and postdoctoral research associates will learn about chemical kinetics theory, QCT dynamics, and quantum chemistry methods in the context of atmospheric chemistry.

这项工作的目的是确定关键有机硝酸盐形成反应的基本动力学，并开发该化学的预测模型。 假设这类反应的主方程方法（ME）方法遭受了稻米 - ramsperger-kassel-marcus（RRKM）理论的失败，这是由于分子内振动能重新分布缓慢（IVR）。 准经典轨迹（QCT）计算将用于评估慢速IVR在由一氧化氮（NO）组成的反应系统中慢速IVR的重要性，该反应系统对形成烷基自由基（RO）或烷基硝酸盐（RONO2）（RONO2）。 如果可行，将构建分析势能面；具有参数化的半经验量子理论（如NDDO -SRP）（忽视双原子差重叠 - 特定反应参数）的直接动力学也将用于计算电位及其梯度。 这两种方法都将使用高级电子结构计算进行评估。 还将计算来自硝酸盐自由基（NO3） +二级烷烃的硝酸盐的温度和压力依赖性产率，还将计算出碳链长度的函数。结果将使其他研究人员能够开发准确的大气化学模型，以预测大气硝酸盐的大气硝酸盐模型产率是温度、压力和 RO2 基团或烯烃的特性的函数。 所有参数化，ME源代码和模型都将在Internet上自由使用。 对非RRKM动力学的见解将适用于对其他非平衡系统（例如燃烧）的研究。 学生和博士后研究伙伴将在大气化学的背景下了解化学动力学理论，QCT动力学和量子化学方法。