Synthesis of chain molecules in regions with partially ionized carbon

A chemical mechanism in which C(+) reactions have the essential role of chain-growing is proposed, and its efficiency under interstellar conditions is investigated. The mechanism is most effective in regions with partially ionized carbon, and, since the reaction rates of radiative association generally become greater as the number of atoms in the reaction increases, the chain growing from C3 to C4 chains is the rate-determining reaction. Higher density, lower temperature, and lower intensity of the external radiation field provide favorable conditions for chain growing, as does the rapid condensation of cloud matter since more carbon remains without changing to CO molecules. TMC-1 is a source which provides conditions leading to the enrichment of chain molecules.