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Two-dimensional spectra of electron collisions with acrylonitrile and methacrylonitrile reveal nuclear dynamics

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2015
Author Regeta Khrystyna, Allan Michael,
Project Chemical and Physical Processes from Electron-Molecule Interactions
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Original article (peer-reviewed)

Journal Journal of Chemical Physics
Volume (Issue) 142
Page(s) 184307
Title of proceedings Journal of Chemical Physics
DOI 10.1063/1.4921204

Open Access

Abstract

Detailed experimental information on the motion of a nuclear packet on a complex (resonant) anion potential surface is obtained by measuring 2-dimensional (2D) electron energy loss spectra. The cross section is plotted as a function of incident electron energy, which determines which resonant anion state is populated, i.e., along which normal coordinate the wave packet is launched, and of the electron energy loss, which reveals into which final states each specific resonant state decays. The 2D spectra are presented for acrylonitrile and methacrylonitrile, at the incident energy range 0.095-1.0 eV, where the incoming electron is temporarily captured in the lowest π∗ orbital. The 2D spectra reveal selectivity patterns with respect to which vibrations are excited in the attachment and de-excited in the detachment. Further insight is gained by recording 1D spectra measured along horizontal, vertical, and diagonal cuts of the 2D spectrum. The methyl group in methacrylonitrile increases the resonance width 7 times. This converts the sharp resonances of acrylonitrile into boomerang structures but preserves the essence of the selectivity patterns. Selectivity of vibrational excitation by higher-lying shape resonances up to 8 eV is also reported.
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