The Gas‐Phase Reaction between O₃ and HO Radical: A Theoretical Study

Abstract

We report a theoretical study on the reaction of ozone with hydroxyl radical, which is important in the chemistry of the atmosphere and in particular participates in stratospheric ozone destruction. The reaction is a complex process that involves, in the first stage, a pre-reactive hydrogen-bonded complex (C1), which is formed previous to two transition states (TS1 and TS2) involving the addition of the hydroxyl radical to ozone, and leads to the formation of HO4 polyoxide radical before the release of the products HO2 and O2. The reaction is computed to be exothermic by 42.72 kcal mol(-1), which compares quite well with the experimental estimate, and the energy barriers of TS1 and TS2 with respect to C1 are computed to be 1.80 and 2.26 kcal mol(-1) at 0 K. A kinetic study based on the variational transition state theory (VTST) predicts a rate constant, at 298 K, of 7.37 x 10(-14) cm3 molecule(-1) s(-1), compared to the experimentally recommended value of 7.25 x 10(-14) cm3 molecule(-1) s(-1).

Theoretical Study on Impact of Single Water Molecule on OH+O3 Reaction

“…The calculated binding energy without the zero-point correction is −10.45 kJ/mol, which is consistent with the reported value of −9.99 kJ/mol at the QCISD(T)/6-311++G(3df, 3pd)//QCISD/6-311++G((d, p) level [63]. In addition, the energy barriers of OH with ozone are calculated here to be 6.48 and 8.57 kJ/mol with respect to the separated reactants, respectively, which are in reasonable agreement with the reported values 7.52 and 9.45 kJ/mol by Anglada et al [18]. Therefore, the test results above reflect that the selected methods can describe the reaction system reliably.…”

“…Due to the importance of the reaction of OH with ozone in the Earth's chemistry, there have been many experimental and theoretical reports [7−18] on the reaction mechanisms and kinetics of the OH+O 3 reaction. The rate constant is calculated to be 7.37×10 14 cm 3 /(molecule s) [18], which is in close agreement with the experimental value of 7.25×10 14 cm 3 /(molecule s) at 298 K [7].…”

Atmospheric Vinyl Alcohol to Acetaldehyde Tautomerization Revisited

“…Letter is fully satisfied, though with a proviso for the tunneling factor, as shown and clarified by Alvarez-Idaboy et al 14,15 and now generally applied for reactions through a prereaction complex with TS energy well above the reactant level (see, for example, Hermans et al 16 ) or slightly below (Mansergas and Anglada et al 17 ). Recently, TST theory was shown to agree reasonably with experiment even for a well-submerged, tight TS (Smith et al 18 ).…”

Effect of NH3 and HCOOH on the H2O2 + HO → HO2 + H2O reaction in the troposphere: competition between the one-step and stepwise mechanisms

“…1 Hydroxyl radical (HO) plays an important role in maintaining the balance of atmospheric composition and forming reactive peroxides. 2,3 Also, from the standpoint of degradation ability, 4,5 HO radicals can react with one ozone molecule to produce molecular oxygen and the HO 2 radicals in the upper atmosphere. As an important reaction in HO x chemistry, the H 2 O 2 + HO reaction shown in eqn (1) can determine the consumption of HO radicals in HO x chain reactions.…”