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Time-resolved relaxation and fragmentation of polycyclic aromatic hydrocarbons investigated in the ultrafast XUV-IR regime

Lee, J. W.L. LU ; Tikhonov, D. S. ; Chopra, P. ; Maclot, S. LU ; Steber, A. L. ; Gruet, S. ; Allum, F. ; Boll, R. ; Cheng, X. and Düsterer, S. , et al. (2021) In Nature Communications 12(1).
Abstract

Polycyclic aromatic hydrocarbons (PAHs) play an important role in interstellar chemistry and are subject to high energy photons that can induce excitation, ionization, and fragmentation. Previous studies have demonstrated electronic relaxation of parent PAH monocations over 10–100 femtoseconds as a result of beyond-Born-Oppenheimer coupling between the electronic and nuclear dynamics. Here, we investigate three PAH molecules: fluorene, phenanthrene, and pyrene, using ultrafast XUV and IR laser pulses. Simultaneous measurements of the ion yields, ion momenta, and electron momenta as a function of laser pulse delay allow a detailed insight into the various molecular processes. We report relaxation times for the electronically excited... (More)

Polycyclic aromatic hydrocarbons (PAHs) play an important role in interstellar chemistry and are subject to high energy photons that can induce excitation, ionization, and fragmentation. Previous studies have demonstrated electronic relaxation of parent PAH monocations over 10–100 femtoseconds as a result of beyond-Born-Oppenheimer coupling between the electronic and nuclear dynamics. Here, we investigate three PAH molecules: fluorene, phenanthrene, and pyrene, using ultrafast XUV and IR laser pulses. Simultaneous measurements of the ion yields, ion momenta, and electron momenta as a function of laser pulse delay allow a detailed insight into the various molecular processes. We report relaxation times for the electronically excited PAH*, PAH+* and PAH2+* states, and show the time-dependent conversion between fragmentation pathways. Additionally, using recoil-frame covariance analysis between ion images, we demonstrate that the dissociation of the PAH2+ ions favors reaction pathways involving two-body breakup and/or loss of neutral fragments totaling an even number of carbon atoms.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Nature Communications
volume
12
issue
1
article number
6107
publisher
Nature Publishing Group
external identifiers
  • pmid:34671016
  • scopus:85117699958
ISSN
2041-1723
DOI
10.1038/s41467-021-26193-z
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2021, The Author(s).
id
2d86ab84-01d1-4980-b535-0ca4de133ff3
date added to LUP
2021-11-05 10:44:39
date last changed
2025-01-26 18:54:28
@article{2d86ab84-01d1-4980-b535-0ca4de133ff3,
  abstract     = {{<p>Polycyclic aromatic hydrocarbons (PAHs) play an important role in interstellar chemistry and are subject to high energy photons that can induce excitation, ionization, and fragmentation. Previous studies have demonstrated electronic relaxation of parent PAH monocations over 10–100 femtoseconds as a result of beyond-Born-Oppenheimer coupling between the electronic and nuclear dynamics. Here, we investigate three PAH molecules: fluorene, phenanthrene, and pyrene, using ultrafast XUV and IR laser pulses. Simultaneous measurements of the ion yields, ion momenta, and electron momenta as a function of laser pulse delay allow a detailed insight into the various molecular processes. We report relaxation times for the electronically excited PAH<sup>*</sup>, PAH<sup>+*</sup> and PAH<sup>2+*</sup> states, and show the time-dependent conversion between fragmentation pathways. Additionally, using recoil-frame covariance analysis between ion images, we demonstrate that the dissociation of the PAH<sup>2+</sup> ions favors reaction pathways involving two-body breakup and/or loss of neutral fragments totaling an even number of carbon atoms.</p>}},
  author       = {{Lee, J. W.L. and Tikhonov, D. S. and Chopra, P. and Maclot, S. and Steber, A. L. and Gruet, S. and Allum, F. and Boll, R. and Cheng, X. and Düsterer, S. and Erk, B. and Garg, D. and He, L. and Heathcote, D. and Johny, M. and Kazemi, M. M. and Köckert, H. and Lahl, J. and Lemmens, A. K. and Loru, D. and Mason, R. and Müller, E. and Mullins, T. and Olshin, P. and Passow, C. and Peschel, J. and Ramm, D. and Rompotis, D. and Schirmel, N. and Trippel, S. and Wiese, J. and Ziaee, F. and Bari, S. and Burt, M. and Küpper, J. and Rijs, A. M. and Rolles, D. and Techert, S. and Eng-Johnsson, P. and Brouard, M. and Vallance, C. and Manschwetus, B. and Schnell, M.}},
  issn         = {{2041-1723}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{Nature Publishing Group}},
  series       = {{Nature Communications}},
  title        = {{Time-resolved relaxation and fragmentation of polycyclic aromatic hydrocarbons investigated in the ultrafast XUV-IR regime}},
  url          = {{http://dx.doi.org/10.1038/s41467-021-26193-z}},
  doi          = {{10.1038/s41467-021-26193-z}},
  volume       = {{12}},
  year         = {{2021}},
}