2026ApJ...996...52G

The chemical evolution of fullerene molecules is an important and interesting topic in astrochemistry. In this work, the coevolution processes occurring in fullerene cations ([C₆₀]⁺ 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., [C₆₀N_(1–5)]⁺ and [C_56/58N]⁺) 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 ([C₆₀N]⁺) 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 (C₆₀) 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.