Abstract

The C3H+ cation plays a pivotal role within the chemical network of dense interstellar clouds. Its relatively slow reaction with molecular hydrogen (H2) suggests that reactions with other species, particularly small hydrocarbons, may play a significant role. In this study, we measured the absolute reaction cross sections of C3H+ with acetylene (C2H2) and the two isomers of C3H4 (allene and propyne). To facilitate the implementation of our experimental data into astrochemical models, we converted the reaction cross sections into rate constants. No temperature dependency was observed for all of the investigated channels. The reaction rates for C3H+ with C2H2 and C3H4, yielding C5H2+ and C4H3+, respectively, are in good agreement with existing data. However, we report a previously unidentified channel in the reaction with C3H4, leading to protonated acetylene C2H3+ with a 30% yield compared to the major product, C4H3+.