Internal-energy-selected measurements of acetylene ions with acetylene at thermal energies

Abstract

A photoelectron-photoion coincidence technique is used to measure the breakdown curve of the primary acetylene ion and the internal-energy dependence of the reaction of C 2H + 2 ions with C 2H 2 molecules, to form C 4H + 2 or C 4H + 3 ions. Both the electronic ground state and the first electronically excited state are included. A possible decay mode of C 2H + 2 in the first excited state, which reconciles seemingly contradictory published experimental data, is proposed. The reaction is studied at thermal collision energies. A statistical model is compared with the data. As a result of this comparison absolute cross sections are derived.