Branching ratios for the fragmentation pathways leading to C₂H₂⁺in electron–ethylene collisions

Abstract

The production of C2H and C2H in the fragmentation of ethylene (C2H4) by electron impact, in the 25–800 eV energy range, is investigated using the DETOF technique. The kinetic energy distributions of both species are obtained and the disentanglement of the two different fragmentation pathways leading to the production of C2H , namely (1) C2H C2H2+ + H2 and (2) C2H C2H2+ + 2H, was performed, providing the absolute cross sections for each channel. It is shown that the branching ratios are independent of the projectile velocity for impact energies above 100 eV, amounting to 80% for channel (1) and 20% for channel (2).