Kinetic isotope effects for the H2 + C2H ↔ C2H2 + H reaction based on the ab initio calculations and a global potential energy surface

This work performs a time-dependent wavepacket study of the H2 + C2H → H + C2H2 reaction on a new ab initio potential energy surface (PES). The PES is constructed using neural network method based on 68 478 geometries with energies calculated at UCCSD(T)-F12a/aug-cc-pVTZ level and covers H2 + C2H↔H + C2H2, H + C2H2 → HCCH2, and HCCH2 radial isomerization reaction regions. The reaction dynamics of H2 + C2H → H + C2H2 are investigated using full-dimensional quantum dynamics method. The initial-state selected reaction probabilities are calculated for reactants in eight vibrational states. The calculated results showed that the H2 vibrational excitation predominantly enhances the reactivity while the excitation of bending mode of C2H slightly inhibits the reaction. The excitations of two stretching modes of C2H molecule have negligible effect on the reactivity. The integral cross section is calculated with J-shift approximation and the mode selectivity in this reaction is discussed. The rate constants over 200-2000 K are calculated and agree well with the experimental measured values.

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Full-dimensional quantum dynamics study of the H2 + C2H → H + C2H2 reaction on an ab initio potential energy surface

Liu-Yang

Shao

Chen

et al. 2016

The Journal of Chemical Physics

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Conclusive determination of ethynyl radical hydrogen abstraction energetics and kinetics*

et al. 2020

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Hydroxide Salts in the Clouds of Venus: Their Effect on the Sulfur Cycle and Cloud Droplet pH

et al. 2021

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The depletion of SO2 and H2O in and above the clouds of Venus (45–65 km) cannot be explained by known gas-phase chemistry and the observed composition of the atmosphere. We apply a full-atmosphere model of Venus to investigate three potential explanations for the SO2 and H2O depletion: (1) varying the below-cloud water vapor (H2O), (2) varying the below-cloud sulfur dioxide (SO2), and (3) the incorporation of chemical reactions inside the sulfuric acid cloud droplets. We find that increasing the below-cloud H2O to explain the SO2 depletion results in a cloud top that is 20 km too high, above-cloud O2 three orders of magnitude greater than observational upper limits, and no SO above 80 km. The SO2 depletion can be explained by decreasing the below-cloud SO2 to 20 ppm. The depletion of SO2 in the clouds can also be explained by the SO2 dissolving into the clouds, if the droplets contain hydroxide salts. These salts buffer the cloud pH. The amount of salts sufficient to explain the SO2 depletion entails a droplet pH of ∼1 at 50 km. Because sulfuric acid is constantly condensing out into the cloud droplets, there must be a continuous and pervasive flux of salts of ≈10−13 mol cm−2 s−1 driving the cloud droplet chemistry. An atmospheric probe can test both of these explanations by measuring the pH of the cloud droplets and the concentrations of gas-phase SO2 below the clouds.

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Kinetic isotope effects for the H₂ + C₂H ↔ C₂H₂ + H reaction based on the ab initio calculations and a global potential energy surface

Cited by 3 publications

References 31 publications

Full-dimensional quantum dynamics study of the H2 + C2H → H + C2H2 reaction on an ab initio potential energy surface

Full-dimensional quantum dynamics study of the H2 + C2H → H + C2H2 reaction on an ab initio potential energy surface

Conclusive determination of ethynyl radical hydrogen abstraction energetics and kinetics*

Hydroxide Salts in the Clouds of Venus: Their Effect on the Sulfur Cycle and Cloud Droplet pH

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