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Issue 48, 2015
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Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

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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.

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

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Publication details

The article was received on 09 Sep 2015, accepted on 13 Nov 2015 and first published on 18 Nov 2015


Article type: Paper
DOI: 10.1039/C5CP05388A
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Citation: Phys. Chem. Chem. Phys., 2015,17, 32464-32471
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    Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

    J. N. Bull, C. W. West and J. R. R. Verlet, Phys. Chem. Chem. Phys., 2015, 17, 32464
    DOI: 10.1039/C5CP05388A

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