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Low-Temperature Kinetic Isotope Effects in CH3OH+H -> CH2OH+H2 Shed Light on the Deuteration of Methanol in Space
- Source :
- J. Phys. Chem. A 2019, 123, 42, 9061
- Publication Year :
- 2020
-
Abstract
- We calculated reaction rate constants including atom tunneling for the hydrogen abstraction reaction CH3OH+H -> CH2OH+H2 with the instanton method. The potential energy was fitted by a neural network, that was trained to UCCSD(T)-F12/VTZ-F12 data. Bimolecular gas-phase rate constants were calculated using microcanonic instanton theory. All H/D isotope patterns on the CH3 group and the incoming H atom are studied. Unimolecular reaction rate constants, representing the reaction on a surface, down to 30 K, are presented for all isotope patterns. At 30 K they range from 4100 for the replacement of the abstracted H by D to ~ 8 for the replacement of the abstracting H to about 2--6 for secondary KIEs. The $^\text{12}$C/$^\text{13}$C kinetic isotope effect is 1.08 at 30 K, while the $^\text{16}$O/$^\text{18}$O kinetic isotope effect is vanishingly small. A simple kinetic surface model using these data predicts high abundances of the deuterated forms of methanol.
- Subjects :
- Physics - Chemical Physics
Astrophysics - Astrophysics of Galaxies
Subjects
Details
- Database :
- arXiv
- Journal :
- J. Phys. Chem. A 2019, 123, 42, 9061
- Publication Type :
- Report
- Accession number :
- edsarx.2009.04308
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1021/acs.jpca.9b07013