Photochemical Reaction Dynamics of O(↑(1)D) with Saturated Hydrocarbons, CH↓(4), C↓(2)H↓(6), and C↓(3)H↓(8), under Bulk Conditions and in van der Waals Complexes

摘要

The reactions of O(↑(1)D) atom with saturated hydrocarbons (RH), CH↓(4), C↓(2)H↓(6), and C↓(3)H↓(8), were studied by monitoring the laser induced fluorescence of products OH in the v" = 0 and 1 levels under bulk conditions and in van der Waals complexes, N↓(2)0·RH. O(↑(1)D) was produced by the ArF excimer laser photolysis of N↓(2)0. Nascent rotational distributions are bimodal in all cases; the low- and high-N components. The former is formed from a long-lived collision complex generated by the insertion process. The collision complex has enough lifetime to randomize excess energy before decomposition. The high-N component is produced in the short-lived insertion process, in which the collision energy of O(↑(1)D) atoms is reflected in the rotational energy. The spin-orbit state in the only half-reactions producing the v" = 0 level shows large population in the low-lying ↑(2)II↓(3/2) state in low-N components, though spin-orbit populations are statistical in other reaction systems studied. The reaction proceeds via a transfer from a singlet reaction surface to a triplet surface keeping the conservation of the electronic angular momentum.