STUDY OF REACTION DYNAMICS VIA MEASUREMENTS OF DIFFERENTIAL CROSS SECTIONS DEPENDENT ON ROTATIONAL ANGULAR MOMENTUM POLARIZATION OF REACTION PRODUCTS

用多普勒分辨偏振光谱法研究了元素气相反应的化学动力学。利用该技术，可以以状态分辨的方式测量微分截面。此外，该方法使我们能够测量反应产物旋转角动量的极化。利用高分辨率染料激光探测无碰撞双原子产物分子，分析其多普勒展宽谱线，提取其微分截面和旋转角动量极化等矢量性质信息。我们研究了O（^1D）或O（^3P）原子与几种简单分子的反应。以下是本研究的总结。1)对于O(^1D)+N_2O→NO+NO反应，NO生成物的旋转角动量是各向同性的，与反应中间体各自由度内的有效能量随机化一致，导致NO生成物具有明显的统计分布，尽管没有深势阱，但NO生成物的国家态分布更明显。2)对于O(^3P)+RH→OH+R反应（RH：饱和烃），反应机理随碰撞能量的变化而变化，传统的简单回弹抽象机理的理解并不普遍适用，特别是在高碰撞能量下。3)对于O(^1D)+RH→OH+R反应，根据RH的大小和OH产物的旋转振动状态提出的两种反应机制在反应中间体的寿命上差别不大。高旋转能级的旋转角动量矢量垂直于散射平面，即C-O-H弯曲运动施加OH旋转。这种趋势与O(^1D)+H_2O反应相似，在O(^1D)+RH反应中，O（^1D）的插入占主导地位。只有用偏振多普勒法才能得到这些结果。本研究的一些发现给出了与以往基于不充分的状态解析测量相反的新认识。以这种方式阐明基本双分子反应的研究对于基本理解化学反应动力学是必不可少的。少

Chemical dynamics of elementary gas phase reactions have been studied via Doppler-resolved polarization spectroscopy. By using this technique, differential cross sections can be measured state-resolved manner. Furthermore, this method enables us to measure the polarization of the rotational angular momentum of reaction products.Collision-free diatomic product molecules were probed with high-resolution dye laser excitation and its Doppler-broadened line profiles were analyzed to extract the information of vector properties such as differential cross sections and rotational angular momentum polarization. We investigated the reactions of O(^1D) or O(^3P) atom with some several simple molecules. The followings are the summaries of this study. 1) For O(^1D)+N_2O→NO+NO reaction, the rotational angular momentum of the NO products are isotropic and consistent with the efficient energy randomization within all the degrees of freedom of reaction intermediates leading to apparent statistical rovi … More brational state distribution of NO products despite the absence of a deep potential well. 2) For O(^3P)+RH→OH+R reaction (RH : saturated hydrocarbons), reaction mechanism varies with collision energy and traditional understanding of a simple rebound abstraction mechanism is not universally proper especially in high collision energy. 3) For O(^1D)+RH→OH+R reaction, the suggested two-type mechanisms dependent on the size of RH and rovibrational state of OH products are not largely different in the lifetime of reactive intermediate. Rotational angular momentum vectors of high rotational levels are perpendicular to the scattering plane, that is, C-O-H bending motion exerts the OH rotation. This trend is similar to the O(^1D)+H_2O reaction, where O(^1D) insertion is dominant as in the O(^1D)+RH reaction.To obtain these finding is only enabled by polarization Doppler method. Some of the findings in this study give new understandings Which are opposite to the previous ones based on insufficient state-resolved measurements. The study elucidating elementary bimolecular reactions in this manner is essential for the fundamental understanding of chemical reaction dynamics. Less