STUDY OF REACTION DYNAMICS OF O(^1D) ATOM VIA THE COMPLETE ROVIBRATIONAL STATE DISTRIBUTION OF REACTION PRODUCTS

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To investigate the dynamics of reactions of O(^1D) atom with simple molecules is indispensable to understand gas-phase chemical reactions form the first principle. This study is especially focused on the O(^1D) + N_2O reaction. The reaction of O(^1D) with N_2O has two product channels(i) NO + NO and (ii) N_2 + O_2. The channel (i) have larger branching ratio than channel (ii) and this channlel is the major source of the stratospheric NO.We have fully determined the rotational state distribution of NO(v=0, 1, 2) products of this reaction via laser-induced fluorescence detection after the production of O(^1D) atom with laser photolysis of N_2O. Collision-free observation was ensured under experimental conditions of low pressure and short pump-probe delay time. It is found that the most part of the rotational distribution is close to the statistical prediction although the population in higher rotational levels j = 100 diminishes more significantly than that of the statistical distributio … More n. The observed statistical trend in the rotational distribution is surprising judging from the absence of very stable intermediates which often enable long lifetime inducing efficient energy transfer within the intermediates. Furthermore, the exothermicity of this reaction of 340 kJ/mol is the largest even among the exothermic O(^1D) reactions typically as large as 180 kJ/mol for OH production. The relation between the observed statistical trend and the release of such large exothermicity without deep potential well is an important question in the reaction dynamics. To obtain deeper insight in this issue, we performed quasi-classical trajectory calculation on an ab initio potential surface. It is suggested that the near-statistical energy distribution in the intermediate in the former half of the reaction and exit channel interaction prohibits the high rotational excitation of the product.We have obtained elementary information to detect the N_2 + O_2 channel under jet expansion and multi-photon ionization spectroscopy. Less