Crossed molecular beam studies on the reaction dynamics of O(D1)+N2O

Abstract

The reaction of oxygen atom in its first singlet excited state with nitrous oxide was investigated under the crossed molecular beam condition. This reaction has two major product channels, NO+NO and N2+O2. The product translational energy distributions and angular distributions of both channels were determined. Using oxygen-18 isotope labeled O(1D) reactant, the newly formed NO can be distinguished from the remaining NO that was contained in the reactant N2O. Both channels have asymmetric and forward-biased angular distributions, suggesting that there is no long-lived collision complex with lifetime longer than its rotational period. The translational energy release of the N2+O2 channel (fT = 0.57) is much higher than that of the NO+NO channel (fT = 0.31). The product energy partitioning into translational, rotational, and vibrational degrees of freedom is discussed to learn more about the reaction mechanism. The branching ratio between the two product channels was estimated. The 46N2O product of the isotope exchange channel, 18O+44N2O-->16O+46N2O, was below the detection limit and therefore, the upper limit of its yield was estimated to be 0.8%.

O(1D) + N2O Reaction: NO Vibrational and Rotational Distributions

“…Lu, Liang, and Lin used a crossed molecular beam apparatus. 10 The O( 1 D) was produced by 157 nm photolysis of O 2 , giving a velocity of 2.1 × 10 5 cm/s.…”

“…The only potential counterexample to this interpretation is the result by Lu, Liang, and Lin. 10 Although they do not directly measure the NO vibrational or rotational distribution, they find that the translational energy deposition in the reaction is 31% (28 kcal/mol out of 89.7 kcal/mol available), a value too high in their view to allow for the high vibrational and rotational excitation observed in the current experiments and in those of Pisano et al Our own measurement of the rotational temperature suggests that the total rotational energy for the two fragments is less than 20 kcal/mol (out of 91.5 kcal/mol available). That would still leave roughly 42 kcal/mol available for vibration, or about 47%.…”

“…8 An earlier paper using this technique was reported by Wang et al 9 Finally, Lu, Liang, and Lin have recently investigated the translational energy distribution of the N 2 + O 2 and NO + NO products from the O( 1 D) + N 2 O reaction. 10 For the NO + NO products, they report that the translational energy release consumes 31% of the available energy. It remains unclear from these studies both what the vibrational distribution actually is and why so many measurements differ from one another.…”

“…Hancock and Haverd measured time-resolved infrared emission of NO( v = 1−14) and concluded that the vibrational distribution for these states decreased monotonically from a maximum population at v = 1 . An earlier paper using this technique was reported by Wang et al Finally, Lu, Liang, and Lin have recently investigated the translational energy distribution of the N 2 + O 2 and NO + NO products from the O( 1 D) + N 2 O reaction . For the NO + NO products, they report that the translational energy release consumes 31% of the available energy.…”

Complete characterization of the constrained geometry bimolecular reaction O(D1)+N2O→NO+NO by three-dimensional velocity map imaging

“…The 1 AЈ ground state potential energy surface of the O͑ 1 D͒ +N 2 O͑ 1 ⌺ + ͒ system was studied by several groups. [26][27][28][29][30][31][32][33][34] The difference in the outcomes of the bulk reaction and of the dimer initiated reaction is striking. The bulk reaction produces fast and highly rotationally excited NO products, and no significant difference between old and new NO products is observed.…”