Fragmentation mechanisms for methane induced by 55 eV, 75 eV, and 100 eV electron impact

The fragmentation of CH4 (2+) dications following 55 eV, 75 eV, and 100 eV electron impact double ionization of methane was studied using a cold target recoil-ion momentum spectroscopy. From the measured momentum of each recoil ion, the momentum of the neutral particles has been deduced and the kine...

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Bibliographic Details
Published in:The Journal of chemical physics 2014-03, Vol.140 (12), p.124303-124303
Main Authors: Wei, B, Zhang, Y, Wang, X, Lu, D, Lu, G C, Zhang, B H, Tang, Y J, Hutton, R, Zou, Y
Format: Article
Language:English
Subjects:
Channels
Electron impact
Energy distribution
FRAGMENTATION
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
IONIZATION
KINETIC ENERGY
METHANE
MOLECULAR IONS
Momentum
NEUTRAL PARTICLES
Recoil ions
SPECTROSCOPY
Spectrum analysis
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Summary:The fragmentation of CH4 (2+) dications following 55 eV, 75 eV, and 100 eV electron impact double ionization of methane was studied using a cold target recoil-ion momentum spectroscopy. From the measured momentum of each recoil ion, the momentum of the neutral particles has been deduced and the kinetic energy release distribution for the different fragmentation channels has been obtained. The doubly charged molecular ions break up into three or more fragments in one or two-step processes, resulting in different signatures in the data. We observed the fragmentation of CH4 (2+) dications through different mechanisms according to the momentum of the neutral particles. For example, our result shows that there are three reaction channels to form CH2 (+), H(+), and H, one synchronous concerted reaction channel and two two-step reaction channels. For even more complicated fragmentation processes of CH4 (2+) dications, the fragmentation mechanism can still be identified in the present measurements. The slopes of the peak in the ion-ion coincidence spectra were also estimated here, as they are also related to the fragmentation mechanism.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4868651