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Title: Simplicity Beneath Complexity: Counting Molecular Electrons Reveals Transients and Kinetics of Photodissociation Reactions

Abstract

Time-resolved pump–probe gas-phase X-ray scattering signals, extrapolated to zero momentum transfer, give a measure of the number of electrons in a system, an effect that arises from the coherent addition of elastic scattering from the electrons. This allows to identify reactive transients and determine the chemical reaction kinetics without the need for extensive scattering simulations or complicated inversion of scattering data. We investigate the photodissociation reaction of trimethylamine and identify two reaction paths upon excitation to the 3p state at 200 nm: a fast dissociation path out of the 3p state to the dimethyl amine radical (16.6±1.2 %) and a slower dissociation via internal conversion to the 3s state (83.4±1.2 %). The time constants for the two reactions are 640±130 fs and 74±6 ps, respectively. Additionally, it is found that the transient dimethyl amine radical has a N-C bond length of 1.45±0.02 Å and a C-N-C bond angle of 118°±4°.

Authors:
ORCiD logo [1];  [2];  [3];  [3];  [2];  [4];  [4];  [4];  [4];  [3];  [2]; ORCiD logo [4]; ORCiD logo [3]
  1. Brown Univ., Providence, RI (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. Univ. of Edinburgh, Scotland (United Kingdom)
  3. Brown Univ., Providence, RI (United States)
  4. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Brown Univ., Providence, RI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; Royal Society of Edinburgh
Contributing Org.:
SLAC National Laboratory
OSTI Identifier:
1532505
Alternate Identifier(s):
OSTI ID: 1504293; OSTI ID: 1596772
Grant/Contract Number:  
AC02-76SF00515; 58507; CRG050414; SC0017995
Resource Type:
Accepted Manuscript
Journal Name:
Angewandte Chemie (International Edition)
Additional Journal Information:
Journal Name: Angewandte Chemie (International Edition); Journal Volume: 58; Journal Issue: 19; Journal ID: ISSN 1433-7851
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; free-electron lasers; gas-phase kinetics; photodissociation dynamics; ultrafast X-ray scattering; free-electron lasers · gas-phase kinetics · photodissociation dynamics · ultrafast X-ray scattering

Citation Formats

Ruddock, Jennifer M., Zotev, Nikola, Stankus, Brian, Yong, Haiwang, Bellshaw, Darren, Boutet, Sébastien, Lane, Thomas J., Liang, Mengning, Carbajo, Sergio, Du, Wenpeng, Kirrander, Adam, Minitti, Michael, and Weber, Peter M. Simplicity Beneath Complexity: Counting Molecular Electrons Reveals Transients and Kinetics of Photodissociation Reactions. United States: N. p., 2019. Web. doi:10.1002/anie.201902228.
Ruddock, Jennifer M., Zotev, Nikola, Stankus, Brian, Yong, Haiwang, Bellshaw, Darren, Boutet, Sébastien, Lane, Thomas J., Liang, Mengning, Carbajo, Sergio, Du, Wenpeng, Kirrander, Adam, Minitti, Michael, & Weber, Peter M. Simplicity Beneath Complexity: Counting Molecular Electrons Reveals Transients and Kinetics of Photodissociation Reactions. United States. doi:10.1002/anie.201902228.
Ruddock, Jennifer M., Zotev, Nikola, Stankus, Brian, Yong, Haiwang, Bellshaw, Darren, Boutet, Sébastien, Lane, Thomas J., Liang, Mengning, Carbajo, Sergio, Du, Wenpeng, Kirrander, Adam, Minitti, Michael, and Weber, Peter M. Wed . "Simplicity Beneath Complexity: Counting Molecular Electrons Reveals Transients and Kinetics of Photodissociation Reactions". United States. doi:10.1002/anie.201902228. https://www.osti.gov/servlets/purl/1532505.
@article{osti_1532505,
title = {Simplicity Beneath Complexity: Counting Molecular Electrons Reveals Transients and Kinetics of Photodissociation Reactions},
author = {Ruddock, Jennifer M. and Zotev, Nikola and Stankus, Brian and Yong, Haiwang and Bellshaw, Darren and Boutet, Sébastien and Lane, Thomas J. and Liang, Mengning and Carbajo, Sergio and Du, Wenpeng and Kirrander, Adam and Minitti, Michael and Weber, Peter M.},
abstractNote = {Time-resolved pump–probe gas-phase X-ray scattering signals, extrapolated to zero momentum transfer, give a measure of the number of electrons in a system, an effect that arises from the coherent addition of elastic scattering from the electrons. This allows to identify reactive transients and determine the chemical reaction kinetics without the need for extensive scattering simulations or complicated inversion of scattering data. We investigate the photodissociation reaction of trimethylamine and identify two reaction paths upon excitation to the 3p state at 200 nm: a fast dissociation path out of the 3p state to the dimethyl amine radical (16.6±1.2 %) and a slower dissociation via internal conversion to the 3s state (83.4±1.2 %). The time constants for the two reactions are 640±130 fs and 74±6 ps, respectively. Additionally, it is found that the transient dimethyl amine radical has a N-C bond length of 1.45±0.02 Å and a C-N-C bond angle of 118°±4°.},
doi = {10.1002/anie.201902228},
journal = {Angewandte Chemie (International Edition)},
number = 19,
volume = 58,
place = {United States},
year = {2019},
month = {3}
}

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    Works referencing / citing this record:

    Ultrafast X-ray scattering reveals vibrational coherence following Rydberg excitation
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    Ultrafast X-ray scattering reveals vibrational coherence following Rydberg excitation
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