Photophysical oxidation of HCHO produces HO2 radicals

Welsh, Blair; Corrigan, Maggie E.; Assaf, Emmanuel; Nauta, Klaas; Sebastianelli, Paolo; Jordan, Meredith J. T.; Fittschen, Christa; Kable, Scott H.

doi:10.1038/s41557-023-01272-4

Cited by 9 publications

(5 citation statements)

References 64 publications

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“…Moreover, the internally excited ground-state molecules can react with O 2 to make HO 2 in so-called "photophysical oxidation" reactions that are energetically inaccessible from thermalized molecules in their vibrational ground-state energy levels. 202 Yet this photochemistry matters in the atmosphere because carbonyl compounds such as formaldehyde are key intermediates in OH and O 3 initiated oxidation of VOCs including isoprene, their photochemistry is a source of HO x radicals, and in some cases this photochemistry might be a step in unintended pathways to the production of long-lived greenhouse gases such as HFC-23 (CF 3 H) from the oxidation of hydrofluoroolefins. 56,203 Notwithstanding the complexities of carbonyl photochemistry outlined above, calculation of the nuclear dynamics in photoexcited molecules (as described in Section 3.2) can simulate changes in electronic state and spin and the competition between bond breaking, isomerization, and relaxation to the ground electronic state.…”

Section: Adiabatic and Diabatic Representationsmentioning

confidence: 99%

“…These competing dynamics can occur over extended time scales, which makes simulation and prediction of quantum yields difficult. Moreover, the internally excited ground-state molecules can react with O 2 to make HO 2 in so-called “photophysical oxidation” reactions that are energetically inaccessible from thermalized molecules in their vibrational ground-state energy levels . Yet this photochemistry matters in the atmosphere because carbonyl compounds such as formaldehyde are key intermediates in OH and O 3 initiated oxidation of VOCs including isoprene, their photochemistry is a source of HO x radicals, and in some cases this photochemistry might be a step in unintended pathways to the production of long-lived greenhouse gases such as HFC-23 (CF 3 H) from the oxidation of hydrofluoroolefins. , …”

Section: Theoretical and Computational Atmospheric Photochemistrymentioning

confidence: 99%

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Perspective on Theoretical and Experimental Advances in Atmospheric Photochemistry

Curchod,

Orr-Ewing

2024

J. Phys. Chem. A

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Research that explores the chemistry of Earth's atmosphere is central to the current understanding of global challenges such as climate change, stratospheric ozone depletion, and poor air quality in urban areas. This research is a synergistic combination of three established domains: earth observation, for example, using satellites, and in situ field measurements; computer modeling of the atmosphere and its chemistry; and laboratory measurements of the properties and reactivity of gas-phase molecules and aerosol particles. The complexity of the interconnected chemical and photochemical reactions which determine the composition of the atmosphere challenges the capacity of laboratory studies to provide the spectroscopic, photochemical, and kinetic data required for computer models. Here, we consider whether predictions from computational chemistry using modern electronic structure theory and nonadiabatic dynamics simulations are becoming sufficiently accurate to supplement quantitative laboratory data for wavelength-dependent absorption cross-sections, photochemical quantum yields, and reaction rate coefficients. Drawing on presentations and discussions from the CECAM workshop on Theoretical and Experimental Advances in Atmospheric Photochemistry held in March 2024, we describe key concepts in the theory of photochemistry, survey the state-of-the-art in computational photochemistry methods, and compare their capabilities with modern experimental laboratory techniques. From such considerations, we offer a perspective on the scope of computational (photo)chemistry methods based on rigorous electronic structure theory to become a fourth core domain of research in atmospheric chemistry.

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Section: Adiabatic and Diabatic Representationsmentioning

confidence: 99%

Section: Theoretical and Computational Atmospheric Photochemistrymentioning

confidence: 99%

Perspective on Theoretical and Experimental Advances in Atmospheric Photochemistry

Curchod,

Orr-Ewing

2024

J. Phys. Chem. A

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“…Formaldehyde (HCHO) primarily emanating from decorative furniture stands out as a prominent indoor pollutant. 1–4 The pursuit of technological advancements for the enduring degradation of indoor HCHO at ambient temperature has become an important concern. Catalytic oxidation technology has shown promise in converting HCHO into carbon dioxide and water, devoid of harmful by-products.…”

Section: Introductionmentioning

confidence: 99%

Insights into the roles of superficial lattice oxygen in formaldehyde oxidation on birnessite

Ma,

Li,

Sun

et al. 2024

Nanoscale

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“…Many involve H atom migration or rearrangement either preceding or as an integral part of the photochemical mechanism. Moreover, they can lead to new atmospheric pathways which can affect radical production and propagation in the troposphere. − …”

Section: Introductionmentioning

confidence: 99%

The Effect of β-Hydrogens on the Tropospheric Photochemistry of Aldehydes: Norrish Type 1, Triple Fragmentation, and Methylketene Formation from Propanal

Kharazmi,

Harrison,

Shaw

et al. 2024

J. Am. Chem. Soc.

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Wavelength and pressure dependent quantum yields (ϕ, QYs) of propanal photolysis have been measured for photolysis wavelengths, λ = 300−330 nm, and buffer gases of 3−10 Torr propanal and 0−757 Torr N 2 . Following laser photolysis, three photochemical pathways were established, using Fourier transform infrared spectroscopy of the stable end-products. Photolysis is dominated by the Norrish Type 1 reaction, which has been reported previously, but with inconsistent quantum yields. The propanal α-hydrogen leads to a 4-center elimination of H 2 , as observed in CH 3 CHO, here leading to methylketene. The presence of hydrogen attached to the β-carbon allows a new photochemical pathway: concerted triple fragmentation into CO + H 2 + C 2 H 4 via a 5-center transition state. Neither of these channels has been reported previously. No evidence for the previously reported C 2 H 6 + CO, C 2 H 4 + H 2 CO or CH 3 + CH 2 CHO channels, nor for phototautomerization to 1−propenol (CH 3 CH�CHOH) was found. Modeling of the wavelength, pressure and collision partner dependence of the QYs allows us to reconcile the previous NT1a results and make recommendations for the quantum yields of all three channels under tropospheric conditions. The general impact of β-hydrogen atoms in the photochemistry of aldehydes is to open up new pathways from cyclic transition states and to reduce the importance of other photolysis or isomerization channels.

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Photophysical oxidation of HCHO produces HO2 radicals

Cited by 9 publications

References 64 publications

Perspective on Theoretical and Experimental Advances in Atmospheric Photochemistry

Perspective on Theoretical and Experimental Advances in Atmospheric Photochemistry

Insights into the roles of superficial lattice oxygen in formaldehyde oxidation on birnessite

The Effect of β-Hydrogens on the Tropospheric Photochemistry of Aldehydes: Norrish Type 1, Triple Fragmentation, and Methylketene Formation from Propanal

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