Details

Autor(en) / Beteiligte

• Hansen, Anne S.
• Bhagde, Trisha
• Moore, Kevin B.
• Moberg, Daniel R.
• Jasper, Ahren W.
• Georgievskii, Yuri
• Vansco, Michael F.
• Klippenstein, Stephen J.
• Lester, Marsha I.

Titel

Watching a hydroperoxyalkyl radical (•QOOH) dissociate

Ist Teil von

• Science (American Association for the Advancement of Science), 2021-08, Vol.373 (6555)

Ort / Verlag

United States: AAAS

Erscheinungsjahr

2021

Quelle

American Association for the Advancement of Science

Beschreibungen/Notizen

• A prototypical hydroperoxyalkyl radical (•QOOH) intermediate, transiently formed in the oxidation of volatile organic compounds, was directly observed through its infrared fingerprint and energy-dependent unimolecular decay to hydroxyl radical and cyclic ether products. Direct time-domain measurements of •QOOH unimolecular dissociation rates over a wide range of energies were found to be in accord with those predicted theoretically using state-of-the-art electronic structure characterizations of the transition state barrier region. Unimolecular decay was enhanced by substantial heavy-atom tunneling involving O-O elongation and C-C-O angle contraction along the reaction pathway. Master equation modeling yielded a fully a priori prediction of the pressure-dependent thermal unimolecular dissociation rates for the •QOOH intermediate—again increased by heavy-atom tunneling—which are required for global models of atmospheric and combustion chemistry.