Low energy H− production by electron collision with small hydrocarbons

Abstract

The production of low-energy H− by electron impact with CH4, C2H2, C2H4, C2H6 and C3H8 has been studied within electron energy range 0−20 eV. The dissociative electron attachment and dipolar dissociation (also known as ion pair production) are contributing to formation of H− in this energy range. A special ion extraction system for collection of low-energy light ions was used. Low-energy H− production rates for all studied molecules are found lower yet similar to those for hydrogen at 14 eV dissociative attachment maximum. A vertical onset of ion yield is observed for the dissociative attachment in CH4, C2H2, and C3H8. The production rate of H− through the dipolar dissociation is observed to be high in the case of C2H4.