Formation of protons from dissociative ionization of methane induced by 54 eV electrons

Abstract

The production mechanisms of protons in dissociation of methane by 54 eV electron impact is investigated using the reaction microscope. By measuring all three charged particles in the final state in triple coincidence, the energy deposited in the target is determined. It is found that the (2${a}_{1}$)${}^{\ensuremath{-}1}$(${\mathit{npt}}_{2}$)${}^{1}$, (2${a}_{1}$)${}^{\ensuremath{-}1}$, (1${t}_{2}$)${}^{\ensuremath{-}2}$(3${a}_{1}$)${}^{1}$, and (2${a}_{1}$)${}^{\ensuremath{-}2}$(3${a}_{1}$)${}^{1}$ states of the intermediate CH${}_{4}$${}^{+}$ make the major contributions to the formation of protons at this incident energy. The decay of each state results in a different kinetic energy distribution of protons. Possible decay mechanisms of these states are analyzed.