A crossed molecular beams study of the reaction of dicarbon molecules with benzene

We conducted the reaction of dicarbon molecules in their electronic ground, C 2 ( X 1 Σ g + ) , and first excited state, C2(a3Πu), with benzene, C6H6(X1A1g). The phenylethynyl radical (C6H5CC; X2A′) and atomic hydrogen were inferred to be the reaction products under single collision conditions. The reactions were indirect via short-lived C8H6 intermediates which decomposed via atomic hydrogen elimination without exit barrier (singlet surface) and via a tight exit transition state (triplet surface). Our experiments suggest that the phenylethynyl radical can be likely formed via bimolecular reactions involving dicarbon molecules with benzene in extreme environments such as circumstellar envelopes of carbon stars, planetary nebulae, and combustion flames.