FORMATION AND CHARGE-SEPARATION REACTIONS OF LARGE MOLECULAR DI-CATIONS WITHIN INTERSTELLAR CLOUDS - CONSEQUENCES FOR COLD CLOUD CHEMICAL EVOLUTION

The presence is suggested of significant abundances of large molecular di-cations (of fullerenes and polycyclic aromatic hydrocarbons) within the interstellar medium. Possible roles are discussed for charge-separating reactions of interstellar di-cations in the chemical evolution of cold, dense interstellar clouds. Several features of such charge-separation reactions are seen to be ideally suited for the production of internally cold, highly kinetically excited ions, and in this capacity such reactions may serve as a driving force for the subsequent occurrence of hydrogen-atom abstraction reactions with the dominant dense-cloud species H-2. Factors influencing reaction sequences of this type are discussed, as are some examples relevant to the formation of molecules detected within interstellar clouds.