Radiolysis of gaseous mixtures of methane with argon or xenon

Abstract

Mixtures of CH₄ with Ar or Xe have been irradiated with 4 MeV electrons at ambient temperatures and atmospheric pressure. Variations of the yields of H₂ and low-molecular-weight hydrocarbons with mixture composition are discussed in terms of the reactions of ions and of excited states. Energy transfer from excited Ar atoms to CH₄, resulting in methylene radical and molecular H₂ formation, appears to account for more than half the enhanced yields of H₂ observed in mixtures of Ar and CH₄. Charge transfer processes can account for the rest. The variations in the yields of hydrocarbon products are also consistent with this type of energy transfer mechanism Evidence for energy transfer from excited Xe atoms to CH₄ is also given.