The Reaction of the Electronically Excited Oxygen Atom O(¹D₂) with Nitrous Oxide

Abstract

An investigation has been made of the relative importance of the possible pathways [2a]–[2d][Formula: see text]for the reaction in the gas phase at room temperature between the excited oxygen atom O(1D2) and N2O, using the photolysis of NO2, O3, and N2O as sources of the excited atom. Measurement of the yields of N2 and NO from the photolysis at 2288 Å of mixtures of NO2 and N2O has led to a value of 1.01 ± 0.06 for k2a/k2b, the ratio of the rate constants for [2a] and [2b], in excellent agreement with the value of 0.99 ± 0.06 obtained from determination of the yields of N2 and NO2 arising from the flash photolysis of O3–N2O mixtures. The isotopic composition of the N2 produced in the photolysis of 15NO2–N2O mixtures indicated that k2c/k2a < 5 × 10 – 3. Furthermore, the value of k2a/(k2b + k2d) = 1.08 ± 0.19, obtained from a study of the effect of CO2 and Xe additions on the yield of N2 from the photolysis of N2O at 2288 Å, suggests that deactivation [2d] does not make an important contribution to the total rate constant for destruction of O(1D2).

The photolysis of N2O at 2139 Å and 1849 Å

“…In the absence of CaHe, the O(aP) disappears via No NO would be consumed, but 0 2 would be produced in addition to that from reaction (2). The O ( 3 P ) atom is known to react with C3Hs with a room-temperature rate constant of 4 The results of the studies with added C3H6 are shown in Table 11.…”

“…The same ratio has also been measured carefully in Preston's laboratory [4] in three systems. From the photolysis of NO2 at 2288 A in the presence of N20, Each laboratory has produced O(l0) in three different ways, and each laboratory obtains internally consistent results.…”

The Role of Excess Kinetic Energy in the Reactions of O(1D) Atoms

“…For personal use only. On the other hand Preston and co-workers (8) found no evidence of a kinetic energy effect on the ratio k,,/k,,. More recently the ratio was redetermined in this laboratory by Wiebe and Paraskevopoulos (9); the value obtained agrees with that of Preston and co-workers and again it was found to be independent of the excess kinetic energy.…”

Relative Rate of Reaction of O(1D2) with N2O

“…In the case of N,O it is thus possible to distinguish between the chemical reaction steps (2a and 2b) and the electronic deactivation step (2c), Although previous work (3,4) has indicated that reaction 2c is not important, the more direct test for 0 ( 3 P ) atoms by the neopentane technique (2) The N, generated in reactions 1 and 2a was measured In every experiment by gas-solid chromatography on a 18 ft 13X Molecular Sieve column. Neopentanol was separated from the unreacted reactants and measured on a 300 ft long, 0.015 in.…”