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研究了基元气相反应的化学动力学。利用这一技术，可以用状态分辨的方式测量微分截面。用高分辨率染料激光激发探测无碰撞双原子产物分子，分析其多普勒展宽谱线，提取微分截面和旋转角动量偏振等矢量性质信息。我们研究了O(^1D)或O(^3P)原子与几个简单分子的反应。以下是本研究的总结。1)对于O(^1D)+N_2O→NO+NO反应，NO产物的转动角动量是各向同性的，并与反应中间产物的有效能量随机化一致，从而产生明显的统计Rovi…在没有深势井的情况下，没有产品的更多摩擦状态分布。2)对于O(^3P)+RH→OH+R反应(RH：饱和烃)，反应机理随碰撞能的不同而不同，传统的简单回弹抽象机理的理解并不普遍适用，特别是在高碰撞能下。3)对于O(^1D)+RH→OH+R反应，所提出的依赖于RH大小和OH产物振荡态的两种反应机理在反应中间体的寿命中没有太大差别。高转动能级的转动角动量矢量垂直于散射面，即C-O-H弯曲运动产生了OH旋转。这一趋势类似于O(^1D)+H2O反应，在O(^1D)+RH反应中，O(^1D)插入占主导地位。这项研究中的一些发现给出了新的理解，这与以前基于不充分的状态分辨测量的理解相反。以这种方式阐明基本的双分子反应对于基本理解化学反应动力学是必不可少的。较少

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