Modeling the electron-impact dissociation of methane

Marcin Ziółkowski, Anna Vikár, Maricris Lodriguito Mayes, Ákos Bencsura, György Lendvay, George C Schatz

Research output: Contribution to journalArticle

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Abstract

The product yield of the electron-impact dissociation of methane has been studied with a combination of three theoretical methods: R-matrix theory to determine the electronically inelastic collisional excitation cross sections, high-level electronic structure methods to determine excited states energies and derivative couplings, and trajectory surface hopping (TSH) calculations to determine branching in the dissociation of the methane excited states to give CH3, CH2, and CH. The calculations involve the lowest 24 excited-state potential surfaces of methane, up to the ionization energy. According to the R-matrix calculations, electron impact preferentially produces triplet excited states, especially for electron kinetic energies close to the dissociation threshold. The potential surfaces of excited states are characterized by numerous avoided and real crossings such that the TSH calculations show rapid cascading down to the lowest excited singlet or triplet states, and then slower the dissociation of these lowest states. Product branching for electron-impact dissociation was therefore estimated by combining the electron-impact excitation cross sections with TSH product branching ratios that were obtained from the lowest singlet and triplet states, with the singlet dissociation giving a comparable formation of CH2 and CH3 while triplet dissociation gives CH3 exclusively. The overall branching in electron-impact dissociation is dominated by CH3 over CH2. A small branching yield for CH is also predicted.

Original languageEnglish
Article number22A510
JournalJournal of Chemical Physics
Volume137
Issue number22
DOIs
Publication statusPublished - Dec 14 2012

Fingerprint

Methane
electron impact
methane
dissociation
Excited states
Electrons
excitation
Trajectories
trajectories
atomic energy levels
products
methylidyne
Ionization potential
cross sections
matrix theory
Kinetic energy
Electronic structure
kinetic energy
electronic structure
Derivatives

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Ziółkowski, M., Vikár, A., Mayes, M. L., Bencsura, Á., Lendvay, G., & Schatz, G. C. (2012). Modeling the electron-impact dissociation of methane. Journal of Chemical Physics, 137(22), [22A510]. https://doi.org/10.1063/1.4733706

Modeling the electron-impact dissociation of methane. / Ziółkowski, Marcin; Vikár, Anna; Mayes, Maricris Lodriguito; Bencsura, Ákos; Lendvay, György; Schatz, George C.

In: Journal of Chemical Physics, Vol. 137, No. 22, 22A510, 14.12.2012.

Research output: Contribution to journalArticle

Ziółkowski, M, Vikár, A, Mayes, ML, Bencsura, Á, Lendvay, G & Schatz, GC 2012, 'Modeling the electron-impact dissociation of methane', Journal of Chemical Physics, vol. 137, no. 22, 22A510. https://doi.org/10.1063/1.4733706
Ziółkowski M, Vikár A, Mayes ML, Bencsura Á, Lendvay G, Schatz GC. Modeling the electron-impact dissociation of methane. Journal of Chemical Physics. 2012 Dec 14;137(22). 22A510. https://doi.org/10.1063/1.4733706
Ziółkowski, Marcin ; Vikár, Anna ; Mayes, Maricris Lodriguito ; Bencsura, Ákos ; Lendvay, György ; Schatz, George C. / Modeling the electron-impact dissociation of methane. In: Journal of Chemical Physics. 2012 ; Vol. 137, No. 22.
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