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Title: Electronic spectroscopy of toluene in helium nanodroplets : evidence for a long-lived excited state.
Authors: Shepperson, Benjamin
Tandy, Jon
Boatwright, Adrian
Feng, Cheng
Spence, Daniel
Shirley, Andrew
Yang, Shengfu
Ellis, Andrew M.
First Published: 23-Sep-2013
Publisher: American Chemical Society
Citation: Journal of Physical Chemistry A, 2013, 117 (50), pp 13591–13595
Abstract: Optical excitation of toluene to the S[subscript 1] electronic state in helium nanodroplets is found to alter the rate of production of the fragment ions C[subscript 7]H[subscript 7][superscript +] and C[subscript 5]H[subscript 5][superscript +] when the droplets are subjected to subsequent electron ionization. The optical excitation process reduces the abundance of C[subscript 7]H[subscript 7][superscript +] ions delivered into the gas phase, whereas C[subscript 5]H[subscript 5][superscript +] ions become more abundant beyond a minimum droplet size. This process contrasts with normal optical depletion spectroscopy, where the optical absorption of a molecular dopant in a helium nanodroplet shrinks the helium droplet, and thus, the electron impact cross-sections because of dissipation of the absorbed energy by evaporative loss of helium atoms. The observations here are interpreted in terms of formation of an excited state in the neutral molecule, which survives for several hundred μs. This long-lived excited state, which is assumed to be the lowest triplet electronic state, shows different cross-sections for production of C[subscript 7]H[subscript 7][superscript +] and C[subscript 5]H[subscript 5][superscript +] relative to the S[subscript 0] state.
DOI Link: 10.1021/jp407577m
ISSN: 1089-5639
eISSN: 1520-5215
Version: Post-print
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2013 American Chemical Society
Description: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry A, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see
Appears in Collections:Published Articles, Dept. of Chemistry

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