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Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

Bull, J.N.; West, C.W.; Verlet, J.R.R.

Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum Thumbnail


Authors

J.N. Bull

C.W. West



Abstract

Photoelectron velocity-map imaging and electronic structure calculations have been used to study the temporary anion (resonance) dynamics of the closed-shell site-specific deprotonated tetracene anion (C18H11−) in the hv = 3.26 eV (380 nm) to 4.13 eV (300 nm) range. In accord with a recent frequency-, angle-, and time-resolved photoelectron imaging study on a related but open-shell polyaromatic radical anion (Chem. Sci., 2015, 6, 1578–1589), population of π*-resonances situated in the detachment continuum efficiently recover the ground electronic state of the anion through ultrafast non-adiabatic dynamics, followed by characteristic statistical electron loss (thermionic emission). The combined electron yield of direct photodetachment and autodetachment from the optically-accessed resonances in C18H11− is several orders of magnitude smaller than thermionic emission from the ground electronic electronic state in the photon energy range studied. This result implies a resilience to prompt photoejection from UV radiation, and the ability of neutral PAH-like species to capture a free electron and form a long-lived molecular anion that ultimately decays by thermionic emission on a millisecond timescale. The attachment mechanism applies to polyaromatic species that cannot support dipole-bound states, and may provide an additional route to forming anions in astrochemical environments.

Citation

Bull, J., West, C., & Verlet, J. (2015). Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum. Physical Chemistry Chemical Physics, 17(48), 32464-32471. https://doi.org/10.1039/c5cp05388a

Journal Article Type Article
Acceptance Date Nov 13, 2015
Publication Date Dec 28, 2015
Deposit Date Dec 18, 2015
Publicly Available Date Mar 29, 2024
Journal Physical Chemistry Chemical Physics
Print ISSN 1463-9076
Electronic ISSN 1463-9084
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 17
Issue 48
Pages 32464-32471
DOI https://doi.org/10.1039/c5cp05388a

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