Combined crossed molecular beams and abinitio investigation of the formation of carbon-bearing molecules in the interstellar medium via neutral–neutral reactions

Abstract

The crossed molecular beams reaction of atomic carbon C(³P_j) with hydrogen sulfide, H₂S, allene, H₂CCCH₂, the vinyl radical, C₂H₃, and deuteroacetylene, C₂HD, have been studied at different collision energies up to 42.2 kJ mol^-1 and combined with high level abinitio calculations. All reactions are barrier-less and are dominated by a carbon–hydrogen exchange to form thioformyl (HCS), butatrienyl (HCCCCH₂), C₃H₂ isomer(s), and deuteriated tricarbon hydride(s). This carbon–hydrogen replacement channel represents a one-step alternative reaction pathway to competing ion–molecule reactions to form complex, carbon-bearing molecules in the interstellar medium as well as in the outflow of carbon stars.