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

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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