The Gas-phase Nitridation Processes of Fullerene Cations in the Interstellar Medium

Abstract The chemical evolution of fullerene molecules is an important and interesting topic in astrochemistry. In this work, the coevolution processes occurring in fullerene cations ([C 60 ] + and [C 58/56 ] + ) in response to ultraviolet radiation and N atom bombardment are first investigated in the gas phase. A series of nitridated fullerene cations (e.g., [C 60 N (1−5) ] + and [C 56/58 N] + ) are observed. An N atom loss channel and no CN-unit loss channel are identified during their photodissociation processes. Through quantum chemistry electronic structure calculations, the structures of the nitridated fullerene cations ([C 60 N] + ) and bonding energies for their formation pathways are obtained. The exothermic energy is relatively high; consequently, the nitridation states and forms of interstellar fullerenes may be complex and stable. Importantly, we infer that the photodissociation of nitridated fullerene species is not involved in the top-down chemical evolution routes of buckminsterfullerene (C 60 ) in the interstellar medium. Moreover, the IR spectra of functionalized (i.e., nitridated, oxygenated, sulfurated, hydrogenated, and deuterated) fullerene cations are discussed in light of astronomical observations.