Kinetics and product channels of the reactions of perhydroxyl with oxygen and hydrogen atoms at 296 K

Abstract

Rate constants for the reactions H02 + O (1) and H02 + H (2) were measured in a discharge-flow apparatus fitted with back-to-back laser-induced fluorescence and vacuum UV resonance fluorescence detectors. The decays of [O] and [H] were monitored under conditions of large excess H02, generated by F + H202 and detected as OH after conversion with added excess NO. kl and k2 were found to be (5.4 ± 0.9) X 10"11 and (7.4 ± 1.2) X 10~n cm1 23 s'1, respectively. The branching ratios of (2), whose three sets of products are OH + OH (2a), H20 + O (2b), and H2 + 02 (2c) were determined by reacting small, known concentrations of H02 with large excess of H and measuring the [OH] and [0] formed. They were found to be 0.87 ± 0.04, 0.04 ± 0.02, and 0.09 ± 0.045, respectively. These results are compared with published data and discussed in terms of the likely course of the molecular interactions.

Dynamics Study of the O + HO2 Reaction Using Two DMBE Potential Energy Surfaces: The Role of Vibrational Excitation

“…Thus, eq 3 corresponds to a hydrogen-atom abstraction mechanism, whereas eq 3 refers to a typical oxygen-atom abstraction. Although both mechanisms have been advanced, 43 the kinetic measurements 6,8,9 suggest that the title reaction should occur preferentially via the oxygen-atom abstraction. In fact, this mechanism has been confirmed experimentally 44 via 16 O/ 18 O substitution and theoretically by our previous calculations.…”

“…Also included for comparison are the available experimental measurements, [2][3][4][5][6][7][8][8][9][10] the recommended values for the range 200 e T/K e 400, and the results from our previous trajectory calculations. 11 The first significant observation refers to the small variation of k(T) with vibrational excitation of HO 2 .…”

“…Moreover, along with the reactions it plays a crucial role in controlling the partitioning among H, OH, and HO 2 radicals. 1 It is therefore not surprising that it has been much studied both experimentally [2][3][4][5][6][7][8][9][10] and theoretically. [11][12][13] Despite such an effort, it has been proposed 14 from atmospheric modeling studies that best agreement with observations could be attained only if the recommended rate constant 15 were scaled down by values up to 75% or so.…”

Combustion Processes and Instabilities in Liquid-Propellant Rocket Engines

“…The rate of reaction 1 is determined from measurements of the inverse reaction HO2 -1-H -> H2 + Q. Experimental data collected in the eighties [20,21,22] have been used to determine the reaction-rate parameters used for this reaction in [12]- [15]. The different constants it, differ only moderately over the range of temperatures of interest (1000 K < T < 4000 K), e.g., by less than ten percent for the two internet-based mechanisms [14,15].…”

A numerical model for one‐dimensional simulation of stratospheric chemistry

“…In a few cases the reactions have been written in a form that gives the final oxidation products. The reaction rate for the reaction H + HO 2 -*• products k 9 , k 1Q , k n has been taken from Sridharan et al (1982) since their study gives the product channels and is the most recent and direct study. In addition, some reactions of importance in the mésosphère have been included for completeness.…”