Criegee intermediates (CIs) are generated from the ozonolysis
of
unsaturated hydrocarbons in the atmosphere. They have an important
role in determining the implications of atmospheric bimolecular reactions
with other atmospheric species. The reaction between CH2OO and H2O2 plays a crucial role in understanding
how CIs impact the HO
x
budget in the atmosphere.
The reaction mechanism and kinetics are critical to atmospheric modeling,
which is a prominent challenge in present-day climate change modeling.
This is particularly true for bimolecular reactions that involve complex
reaction sequences. Here, we report the mechanism and quantitative
kinetics of the CH2OO + H2O2 reaction
by using a novel dual-level strategy that contains W3X-L//CCSD(T)-F12a/cc-pVTZ-F12
for the transition state theory and M11-L/MG3S functional method for
direct dynamics calculations using canonical variational transition
state theory with small-curvature tunneling to obtain both recrossing
effects and tunneling. The present work shows that the CH2OO + H2O2 reaction has a negative temperature
dependency with the decrease in the rate constant of CH2OO + H2O2 from 1.31 × 10–13 cm3 molecule–1 s–1 to 3.80 × 10–14 cm3 molecule–1 s–1 between 200 and 350 K. The
calculated results also show that the CH2OO + H2O2 reaction can have an impact on the H2O2 profile under certain atmospheric conditions. The present
findings should have implications for the quantitative kinetics of
Criegee intermediates with other hydroperoxides.
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