Spectroscopic and Kinetic Studies of Alkoxy Radicals

9712381 Dibble这个项目使用激光诱导荧光和量子化学计算来确定烷氧基的异构化和解离反应的速率系数。这些单分子反应的特征很差，但烷氧基通常会解离或异构化，而不是与大气中的分子氧反应。这三个反应之间的竞争对整个对流层臭氧的形成有重要的影响。本研究获得的数据将有助于提高我们对烷氧基化学的理解，并有助于研究涉及烷氧基的许多其他关键大气反应。LiF将用于探测烷氧基的瞬时浓度。近紫外区LiF在烷氧基的光谱和动力学研究中显示出巨大的应用价值。它具有直接测定异构化和离解反应的绝对速率系数所需的灵敏度和时间分辨率。在这项研究中，将测定至少具有四个碳原子的烷氧基的激光诱导荧光光谱。这项技术可以区分较大的烷氧基的异构体。对于那些不适合用这种实验方法研究的烷氧基，将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。对可获得实验数据的物种的基准研究将被用作估计尚未通过实验确定的单分子反应速率的参考。

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.