Photophysical oxidation of HCHO produces HO2 radicals - Archive ouverte HAL
Article Dans Une Revue Nature Chemistry Année : 2023

Photophysical oxidation of HCHO produces HO2 radicals

Blair Welsh
Maggie Corrigan
  • Fonction : Auteur
Emmanuel Assaf
Klaas Nauta
  • Fonction : Auteur
Paolo Sebastianelli
  • Fonction : Auteur
Meredith Jordan
Scott Kable

Résumé

Formaldehyde, HCHO, is the highest-volume carbonyl in the atmosphere. It absorbs sunlight at wavelengths shorter than 330 nm and photolyses to form H and HCO radicals, which then react with O2 to form HO2. Here we show HCHO has an additional HO2 formation pathway. At photolysis energies below the energetic threshold for radical formation we directly detect HO2 at low pressures by cavity ring-down spectroscopy and indirectly detect HO2 at 1 bar by Fourier-transform infrared spectroscopy end-product analysis. Supported by electronic structure theory and master equation simulations, we attribute this HO2 to photophysical oxidation (PPO): photoexcited HCHO relaxes non-radiatively to the ground electronic state where the far-from-equilibrium, vibrationally activated HCHO molecules react with thermal O2. PPO is likely to be a general mechanism in tropospheric chemistry and, unlike photolysis, PPO will increase with increasing O2 pressure.

Domaines

Chimie
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Dates et versions

hal-04248377 , version 1 (18-10-2023)

Identifiants

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Blair Welsh, Maggie Corrigan, Emmanuel Assaf, Klaas Nauta, Paolo Sebastianelli, et al.. Photophysical oxidation of HCHO produces HO2 radicals. Nature Chemistry, 2023, 15 (10), pp.1350-1357. ⟨10.1038/s41557-023-01272-4⟩. ⟨hal-04248377⟩
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