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

The fragmentation of CH{sub 4}{sup 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 CH{sub 4}{sup 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 CH{sub 2}{sup +}, H{sup +}, and H, one synchronous concerted reaction channel and two two-step reaction channels. For even more complicated fragmentation processes of CH{sub 4}{sup 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.
Authors:
; ; ; ; ; ;  [1] ;  [2] ; ;  [3]
  1. Applied Ion Beam Physics Laboratory, Fudan University, Key Laboratory of the Ministry of Education, Shanghai 200433 (China)
  2. (China)
  3. Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900 (China)
Publication Date:
OSTI Identifier:
22253398
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; FRAGMENTATION; IONIZATION; KINETIC ENERGY; METHANE; MOLECULAR IONS; NEUTRAL PARTICLES; SPECTROSCOPY