2019ApJ...887...70Z

Besides buckminsterfullerene (C₆₀), other fullerenes and their derivatives may also reside in space. In this work, we study the formation and photodissociation processes of astronomically relevant fullerene/anthracene (C₁₄H₁₀) cluster cations in the gas phase. Experiments are carried out using a quadrupole ion trap in combination with time-of-flight mass spectrometry. The results show that fullerene (C₆₀ and C₇₀)/anthracene (i.e., [(C₁₄H₁₀)_nC₆₀]⁺ and [(C₁₄H₁₀)_nC₇₀]⁺), fullerene (C₅₆ and C₅₈)/anthracene (i.e., [(C₁₄H₁₀)_nC₅₆]⁺ and [(C₁₄H₁₀)_nC₅₈]⁺), and fullerene (C₆₆ and C₆₈)/anthracene (i.e., [(C₁₄H₁₀)_nC₆₆]⁺ and [(C₁₄H₁₀)_nC₆₈]⁺) cluster cations, are formed in the gas phase through an ion-molecule reaction pathway. With irradiation, all the fullerene/anthracene cluster cations dissociate into monoanthracene and fullerene species without dehydrogenation. The structure of newly formed fullerene/anthracene cluster cations and the bonding energy for these reaction pathways are investigated with quantum chemistry calculations. Our results provide a growth route toward large fullerene derivatives in a bottom-up process and insight into their photoevolution behavior in the interstellar medium, and clearly, when conditions are favorable, fullerene/polycyclic aromatic hydrocarbon clusters can form efficiently. In addition, these clusters (from 80 to 154 atoms or ∼2 nm in size) offer a good model for understanding the physical-chemical processes involved in the formation and evolution of carbon dust grains in space, and provide candidates of interest for the diffuse interstellar bands that could motivate spectroscopic studies.