Radiative association and the synthesis of long carbon chain molecules in interstellar clouds

An attractively simple scheme by which molecules having long carbon chains are formed in interstellar clouds through the radiative association family Cn+C+→Cn+1++hν is examined. It is rejected as probably being much too inefficient. Other schemes involve the synthesis of a big molecule in a single step, as for example NH3+CH3+→NH3×CH3++hv on which related flow-tube experiments have been performed. If a competing exothermic channel exists, it will in general severely suppress the radiative association rate coefficient.