Simplicity Beneath Complexity: Counting Molecular Electrons Reveals Transients and Kinetics of Photodissociation Reactions
[1];
[4];
[3]
- Department of Chemistry Brown University 324 Brook St Providence RI 02912 USA, SLAC National Accelerator Laboratory 2575 Sandhill Rd Menlo Park CA 94025 USA
- EaStCHEM School of Chemistry University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
- Department of Chemistry Brown University 324 Brook St Providence RI 02912 USA
- SLAC National Accelerator Laboratory 2575 Sandhill Rd Menlo Park CA 94025 USA
Abstract Time‐resolved pump–probe gas‐phase X‐ray scattering signals, extrapolated to zero momentum transfer, provide 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 examine 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°.
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC02-76SF00515
- OSTI ID:
- 1504297
- Journal Information:
- Angewandte Chemie, Journal Name: Angewandte Chemie Vol. 131 Journal Issue: 19; ISSN 0044-8249
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- Germany
- Language:
- English
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Simplicity beneath Complexity: Counting Molecular Electrons Reveals Transients and Kinetics of Photodissociation Reactions
Photodissociating trimethylamine at 193 nm to probe dynamics at a conical intersection and to calibrate detection efficiency of radical products