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Title: Dissociation dynamics of 3- and 4-nitrotoluene radical cations: Coherently driven C–NO 2 bond homolysis

Abstract

Monosubstituted nitrotoluenes serve as important model compounds for nitroaromatic energetic molecules such as trinitrotoluene. This work investigates the ultrafast nuclear dynamics of 3- and 4-nitrotoluene radical cations using femtosecond pump-probe measurements and the results of density functional theory calculations. Strong-field adiabatic ionization of 3- and 4-nitrotoluene using 1500 nm, 18 fs pulses produces radical cations in the ground electronic state with distinct coherent vibrational excitations. In both nitrotoluene isomers, a one-photon excitation with the probe pulse results in NO2 loss to form C7H+7, which exhibits out-of-phase oscillations in yield with the parent molecular ion. The oscillations in 4-nitrotoluene with a period of 470 fs are attributed to the torsional motion of the NO2 group based on theoretical results showing that the dominant relaxation pathway in 4-nitrotoluene radical cations involves the rotation of the NO2 group away from the planar geometry. The distinctly faster oscillation period of 216 fs in 3-nitrotoluene is attributed to an in-plane bending motion of the NO2 and CH3 moieties based on analysis of the normal modes. These results demonstrate that coherent nuclear motions determine the probability of C–NO2 homolysis in the nitrotoluene radical cations upon optical excitation within several hundred femtoseconds of the initial ionization event.

Authors:
 [1]; ORCiD logo [2];  [3]; ORCiD logo [1]
  1. Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, USA
  2. Department of Physics, Florida A&,M University, Tallahassee, Florida 32307, USA
  3. Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284, USA
Publication Date:
Research Org.:
Virginia Commonwealth Univ., Richmond, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1540180
Alternate Identifier(s):
OSTI ID: 1431391
Grant/Contract Number:  
FG02-96ER45579
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 148; Journal Issue: 13; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
Chemistry; Physics

Citation Formats

Ampadu Boateng, Derrick, Gutsev, Gennady L., Jena, Puru, and Tibbetts, Katharine Moore. Dissociation dynamics of 3- and 4-nitrotoluene radical cations: Coherently driven C–NO 2 bond homolysis. United States: N. p., 2018. Web. doi:10.1063/1.5024892.
Ampadu Boateng, Derrick, Gutsev, Gennady L., Jena, Puru, & Tibbetts, Katharine Moore. Dissociation dynamics of 3- and 4-nitrotoluene radical cations: Coherently driven C–NO 2 bond homolysis. United States. doi:10.1063/1.5024892.
Ampadu Boateng, Derrick, Gutsev, Gennady L., Jena, Puru, and Tibbetts, Katharine Moore. Sat . "Dissociation dynamics of 3- and 4-nitrotoluene radical cations: Coherently driven C–NO 2 bond homolysis". United States. doi:10.1063/1.5024892. https://www.osti.gov/servlets/purl/1540180.
@article{osti_1540180,
title = {Dissociation dynamics of 3- and 4-nitrotoluene radical cations: Coherently driven C–NO 2 bond homolysis},
author = {Ampadu Boateng, Derrick and Gutsev, Gennady L. and Jena, Puru and Tibbetts, Katharine Moore},
abstractNote = {Monosubstituted nitrotoluenes serve as important model compounds for nitroaromatic energetic molecules such as trinitrotoluene. This work investigates the ultrafast nuclear dynamics of 3- and 4-nitrotoluene radical cations using femtosecond pump-probe measurements and the results of density functional theory calculations. Strong-field adiabatic ionization of 3- and 4-nitrotoluene using 1500 nm, 18 fs pulses produces radical cations in the ground electronic state with distinct coherent vibrational excitations. In both nitrotoluene isomers, a one-photon excitation with the probe pulse results in NO2 loss to form C7H+7, which exhibits out-of-phase oscillations in yield with the parent molecular ion. The oscillations in 4-nitrotoluene with a period of 470 fs are attributed to the torsional motion of the NO2 group based on theoretical results showing that the dominant relaxation pathway in 4-nitrotoluene radical cations involves the rotation of the NO2 group away from the planar geometry. The distinctly faster oscillation period of 216 fs in 3-nitrotoluene is attributed to an in-plane bending motion of the NO2 and CH3 moieties based on analysis of the normal modes. These results demonstrate that coherent nuclear motions determine the probability of C–NO2 homolysis in the nitrotoluene radical cations upon optical excitation within several hundred femtoseconds of the initial ionization event.},
doi = {10.1063/1.5024892},
journal = {Journal of Chemical Physics},
number = 13,
volume = 148,
place = {United States},
year = {2018},
month = {4}
}

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Cited by: 4 works
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Works referenced in this record:

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journal, April 1993

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