Laboratory formation and photo-chemistry of fullerene/anthracene cluster cations

TL;DR

This study investigates the formation, structure, and photo-dissociation of fullerene/anthracene cluster cations in space-like conditions, revealing their potential role in cosmic dust formation and spectral features.

Contribution

It provides experimental and theoretical insights into the formation and dissociation of fullerene/anthracene clusters, a novel pathway for large fullerene derivative growth in space.

Findings

Fullerene/anthracene clusters form via ion-molecule reactions.

Clusters dissociate into mono-anthracene and fullerene without dehydrogenation.

Clusters serve as models for cosmic dust and DIBs analysis.

Abstract

Besides buckminsterfullerene (C60), other fullerenes and their derivatives may also reside in space. In this work, we study the formation and photo-dissociation processes of astronomically relevant fullerene/anthracene (C14H10) cluster cations in the gas phase. Experiments are carried out using a quadrupole ion trap (QIT) in combination with time-of-flight (TOF) 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 mono$-$anthracene 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 towards large fullerene derivatives in a bottom-up process and insight in their photo-evolution behavior in the ISM, and clearly, when conditions are favorable, fullerene/PAH 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 DIBs that could motivate spectroscopic studies.