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.