Probing colossal carbon rings

Marlton, Samuel J. P., Buntine, Jack T., Watkins, Patrick, Liu, Chang, Jacovella, Ugo, Carrascosa, Eduardo, Bull, James N. ORCID: https://orcid.org/0000-0003-0953-1716 and Bieske, Evan J. (2023) Probing colossal carbon rings. The Journal of Physical Chemistry A, 127 (5). pp. 1168-1178. ISSN 1089-5639

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Abstract

Carbon aggregates containing between 10 and 30 atoms preferentially arrange themselves as planar rings. To learn more about this exotic allotrope of carbon, electronic spectra are measured for even cyclo[n]carbon radical cations (C14+ –C36+) using two-color photodissociation action spectroscopy. To eliminate spectral contributions from other isomers, the target cyclo[n]carbon radical cations are isomer-selected using a drift tube ion mobility spectrometer prior to spectroscopic interrogation. The electronic spectra exhibit sharp transitions spanning the visible and near-infrared spectral regions with the main absorption band shifting progressively to longer wavelength by ≈100 nm for every additional two carbon atoms. This behavior is rationalized with a Hückel theory model describing the energies of the in-plane and out-of-plane π orbitals. Photoexcitation of smaller carbon rings leads preferentially to neutral C3 and C5 loss, whereas rings larger than C24+ tend to also decompose into two smaller rings, which, when possible, have aromatic stability. Generally, the observed charged photofragments correspond to low energy fragment pairs, as predicted by density functional theory calculations (CAM-B3LYP-D3(BJ)/cc-pVDZ). Using action spectroscopy it is confirmed that C14+ and C18+ photofragments from C28+ rings have cyclic structures.

Item Type: Article
Additional Information: Funding Information: This research was supported under the Australian Research Council’s Discovery Project funding scheme (Project Numbers DP150101427 and DP160100474). U.J. acknowledges support from the Swiss National Science Foundation (P2EZP2_178429).
Uncontrolled Keywords: physical and theoretical chemistry ,/dk/atira/pure/subjectarea/asjc/1600/1606
Faculty \ School: Faculty of Science > School of Chemistry
UEA Research Groups: Faculty of Science > Research Groups > Centre for Photonics and Quantum Science
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Depositing User: LivePure Connector
Date Deposited: 27 Jan 2023 18:30
Last Modified: 27 Jan 2024 01:38
URI: https://ueaeprints.uea.ac.uk/id/eprint/90851
DOI: 10.1021/acs.jpca.2c07068

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