Spectroscopic and Kinetic Studies of Alkoxy Radicals

小行星9712381 本计画利用雷射诱导萤光（LIF）与量子化学计算来决定烷氧基自由基之异构化与解离反应之速率系数。这些单分子反应的特点很差，但烷氧基自由基通常离解或异构化，而不是与分子氧在大气中反应。这三种反应之间的竞争对整个对流层的臭氧形成有重要的影响。在这项研究中获得的数据将有助于提高我们对烷氧基自由基化学的理解，并有助于研究许多其他涉及烷氧基自由基的重要大气反应。 LIF将用于探测烷氧基自由基的瞬时浓度。近紫外激光诱导荧光在烷氧基自由基的光谱和动力学研究中具有巨大的应用价值。它具有灵敏度和时间分辨率进行异构化和解离反应的绝对速率系数的直接测定。在这项研究中，具有至少四个碳原子的烷氧基自由基的激光诱导荧光光谱将被确定。该技术可以区分较大烷氧基的异构体。对于那些不适合通过这种实验方法研究的烷氧基，将采用量子力学计算来估计结构对异构化和解离反应速率的影响。对已有实验数据的物种的基准研究将用作参考，以估计尚未通过实验确定的单分子反应速率。

9712381 Dibble This project uses laser-induced fluorescence (LIF) and quantum chemical calculations to determine rate coefficients for the isomerization and dissociation reactions of alkoxy radicals. These unimolecular reactions are poorly characterized, yet alkoxy radicals commonly dissociate or isomerize rather than reacting with molecular oxygen in the atmosphere. The competition among these three reactions has important implications for ozone formation throughout the troposphere. Data obtained in this study will help improve our understanding of alkoxy radical chemistry, and aid in the study of many other crucial atmospheric reactions involving alkoxy radicals. LIF will be used to probe transient concentrations of alkoxy radicals. LIF in the near UV has demonstrated enormous utility for spectroscopic and kinetic studies of alkoxy radicals. It possesses the sensitivity and time resolution necessary to carry out direct determination of absolute rate coefficients for isomerization and dissociation reactions. In this study, the LIF spectra of alkoxy radicals possessing at least four carbon atoms will be determined. The technique can distinguish between isomers of the larger alkoxy radicals. For those alkoxy radicals which are not amenable to study by this experimental approach, quantum mechanical calculations will be employed to estimate the effects of structure on reaction rates for isomerization and dissociation. Benchmark studies on species for which experimental data is available will be used as a reference to estimate unimolecular reaction rates not yet established by experiment.