Laser-induced fragmentation of coronene cations

Abstract

Polycyclic aromatic hydrocarbons are an important component of the interstellar medium of galaxies and photochemistry plays a key role in the evolution of these species in space. Here, we explore the photofragmentation behaviour of the coronene cation (C24H12+) using time of flight mass spectrometry. The experiments show photodissociation fragmentation channels including the formation of bare carbon clusters (Cn+) and hydrocarbon chains (CnHx+). The mass spectrum of coronene is dominated by peaks from C11+ and C7H+. Density functional theory was used to calculate relative energies, potential dissociation pathways, and possible structures for relevant species. We identify 6-6 to 5-7 ring isomerisation as a key step in the formation of both the bare carbon clusters and the hydrocarbon chains observed in this study. We present the dissociation mechanism outlined here as a potential formation route for C60 and other astrochemically relevant species.

17 pages, 12 figure. Version submitted after referee report to PCCP. Supplementary information available at https://www.rsc.org/suppdata/d4/cp/d4cp01301h/d4cp01301h1.pdf

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• PAH Spectral Diversity in NGC 7027 and the Evolution of Aromatic Carriers
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