O(1D) reaction with methane studied by state resolved scattering distribution measurements of methyl radicals

Suzuki, Toshinori

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https://hdl.handle.net/2142/55842 Copy

Description

Title

O(1D) reaction with methane studied by state resolved scattering distribution measurements of methyl radicals

Author(s)

Suzuki, Toshinori

Issue Date

2014-06-17

Keyword(s)

Mini-symposium: Spectroscopy in Kinetics and Dynamics

Abstract

The scattering distributions of state-selected methyl radicals are measured for the O($^1$D$_2$) reaction with methane using a crossed molecular beam ion imaging method at collision energies of 0.9 – 6.8 kcal/mol. The results are compared with the reaction with deuterated methane to examine the isotope effects. The scattering distributions exhibit contributions from both the insertion and abstraction pathways respectively on the ground and excited-state potential energy surfaces. Insertion is the main pathway, and it provides a strongly forward-enhanced angular distribution of methyl radicals. Abstraction is a minor pathway, causing backward scattering of methyl radicals with a discrete speed distribution. From the collision energy dependence of the abstraction/insertion ratio, the barrier height for the abstraction pathway is estimated for O($^1$D$_2$) with CH$_4$ and CD$_4$, respectively. The insertion pathway of the O($^1$D$_2$) reaction with CH$_4$ has a narrower angular width in the forward scattering and a larger insertion/abstraction ratio than the reaction with CD$_4$, which indicate that the insertion reaction with CH$_4$ has a larger cross section and a shorter reaction time than the reaction with CD$_4$. Additionally, while the insertion reaction with CD$_4$ exhibits strong angular dependence of the CD$_3$ speed distribution, CH$_3$ exhibits considerably smaller dependence. The result suggests that, although intramolecular vibrational redistribution (IVR) within the lifetime of the methanol intermediate is restrictive in both isotopomers, relatively more extensive IVR occurs in CD$_3$OD than CH$_3$OH, presumably due to the higher vibrational state density.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/55842

DOI

https://doi.org/10.15278/isms.2014.TC01

Copyright and License Information

Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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