Photophysics and Photochemistry of Gas Phase Organic Compounds and Biomolecules Studied Using Orientation via Uniform Electric Fields

俄勒冈州立大学的魏孔得到了实验物理化学计划的资助，利用激光诱导荧光和共振增强多光子电离，将她对场定向分子光谱的研究扩展到中等大小的有机分子和生物相关物种。具体地说，建议研究硝基苯和硝基甲苯异构体的势能表面：(1)鉴定参与电子跃迁的物种的对称性；(2)观察光解离动力学；(3)评估甲基取代的影响；(4)研究邻硝基甲苯中的分子内氢夺取等邻位效应。在这些研究之后，将观察核酸碱基及其甲基衍生物的激发几率，以确定这些取代的影响。这些研究将通过选择性地相对于光的偏振来定向分子，从而加深对有机化合物和生物相关物种与光相互作用的细节的基本理解。这项工作应用于生物物理学，这些方法可能被应用于研究紫外线诱导DNA损伤的机制，以及利用紫外线激活抗肿瘤药物的机制。

Wei Kong of Oregon State University is supported by a grant from the Experimental Physical Chemistry Program to extend her studies of the spectroscopy of field oriented molecules to medium sized organic molecules and biologically relevant species using laser induced fluorescence and resonance enhanced multiphoton ionization. Specifically, it is proposed to investigate the potental surfaces of nitrobenzene and the nitrotoluene isomers to: (1) identify the symmetry of the species involved in the electronic transitions; (2) observe the photodissociation dynamics; (3) assess the effects of methyl substitution and (4) investigate ortho effects such as intramolecular hydrogen abstraction in o-nitrotoluene. These studies will be followed by observations of the excitation probabilities of nucleic acid bases and their methyl derivatives to determine the effects of these substitutions.The studies will lead to a deeper fundamental understanding of the details of the interaction of organic compounds and biologically relevant species with light by selectively orienting the molecules with respect to the polarization of that light. The work has application to biophysics and the methods can potentially be applied to study the mechanisms involved in inducing lesions in DNA by ultraviolet light and in the use of this light to activate antitumor drugs.