Reaction rate constants of HO2+O3 in the temperature range 233–400 K

Abstract

The reaction rate constants of HO2+O3 were measured as a function of temperature. HO2 was produced by the reaction sequence: Cl+CH3OH→CH2OH+HCl and CH2OH+O2→HO2+CH2O. HO2 was detected by the OH(A–X) fluorescence produced by photoexcitation of HO2 at 147 nm. The reaction rate constants are represented by k(T)=(1.8±0.6)×10−14 exp[−(680±148)/T] cm3/s in 253–400 K, and are nearly a constant of (1.3±0.3)×10−15 cm3/s in 233–253 K.

Helium Nanodroplet Isolation Spectroscopy and ab Initio Calculations of HO3(O2)n Clusters

“…[7,8] The most significant difference between this 2 A structure and the 4 A' trans-HO 3 ÀO 2 H-bound complex computed here is the HOOO dihedral angle within the HO 3 moiety. [7,8] The most significant difference between this 2 A structure and the 4 A' trans-HO 3 ÀO 2 H-bound complex computed here is the HOOO dihedral angle within the HO 3 moiety.…”

“…As mentioned above, previous CASSCF computations of Viegas and Varandas and Xu and Lin predicted an HO 3 ÀO 2 complex ( 2 A) to be a stable minimum in the exit channel of the HO 2 + O 3 hydrogen abstraction reaction (MIN3). [7,8] The most significant difference between this 2 A structure and the 4 A' trans-HO 3 ÀO 2 H-bound complex computed here is the HOOO dihedral angle within the HO 3 moiety. Both structures consist of a hydrogen-bonded interaction between the HO 3 and O 2 fragments.…”

“…The associated dihedral angle within the 4 A' structure is 1808 (trans-HO 3 ), while the 2 A structure is nonplanar with a HOOO dihedral angle of 99.98. The mode of the imaginary frequency suggests that the 4 A MIN3 species is the transition state between the H-bonded cis-and trans-HO 3 ÀO 2 isomers on the quartet surface. Starting from the MIN3 geometry reported in ref.…”

“…[1] For example, the reaction between HO 2 and O 3 to give O 2 and HO 3 is the rate-limiting step in the HO x cycle, which is thought to be responsible for almost half of stratospheric O 3 loss. [2] There is experimental evidence that this reaction proceeds through two competing channels, [3,4] which correspond to either hydrogen abstraction from HO 2 by O 3 or oxygen abstraction from O 3 by HO 2 . Using isotopic labeling, Nelson and Zahniser inferred from product branching ratios that the reaction proceeds mainly through H atom abstraction.…”

Ultraviolet radiation curable epoxy resin encapsulant for light emitting diodes

“…For this reason, there have been some theoretical and experimental reports on the reactions of HO 2 with species relative to in atmospheric chemistry. For example, the reaction mechanisms and kinetics of HO 2 with ozone5–15 have been extensively investigated as it has a key role in ozone depletion. The HO 2 radical reacts with carbonyls and acetone16–20, which have been studied.…”