Laboratory photo-chemistry of pyrene clusters: an efficient way to form large PAHs

Abstract

In this work, we study the photodissociation processes of small PAH clusters (e.g., pyrene clusters). The experiments are carried out using a quadrupole ion trap in combination with time-of-flight (QIT-TOF) mass spectrometry. The results show that pyrene clusters are converted into larger PAHs under the influence of a strong radiation field. Specifically, pyrene dimer cations (e.g., [C${}_{16}$H${}_{10}$$-$C${}_{16}$H${}_9$]${}^{+}$ or C${}_{32}$H${}_{19}$${}^{+}$), will photo-dehydrogenate and photo-isomerize to fully aromatic cations (PAHs) (e.g., C${}_{32}$H${}_{16}$${}^{+}$) with laser irradiation. The structure of new formed PAHs and the dissociation energy for these reaction pathways are investigated with quantum chemical calculations. These studies provide a novel efficient evolution routes for the formation of large PAHs in the interstellar medium (ISM) in a bottom-up process that will counteract the top-down conversion of large PAHs into rings and chains, and provide a reservoir of large PAHs that can be converted into C${}_{60}$ and other fullerenes and large carbon cages.

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Cited by in corpus (6)

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• Synthesizing carbon nanotubes in space
• Fragmentation and isomerization of polycyclic aromatic hydrocarbons in the interstellar medium: coronene as a case study
• Laser-induced fragmentation of coronene cations
• Laboratory formation and photo-chemistry of fullerene/anthracene cluster cations