Electron impact induced anion production in acetylene

A detailed experimental investigation of electron induced anion production in acetylene, C2H2, in the energy range between 1 and 90 eV is presented. The anions are formed by two processes in this energy range: dissociative electron attachment (DEA) and dipolar dissociation (DD). DEA in C2H2 is found to lead to the formation of H- and C2-/C2H- through excitation of resonances in the electron energy range 1-15 eV. These anionic fragments are formed with super thermal kinetic energy and reveal no anisotropy in the angular distributions. DD in C2H2 leads to the formation of H-, C-/CH- and C2-/C 2H- with threshold energies of 15.7, 20.0 and 16.5 eV respectively. The measured anion yields have been used to calculate anion production rates for H-, C-/CH- and C 2-/C2H- in Titan's ionosphere.