Excited state non-adiabatic dynamics of N-methylpyrrole: A time-resolved photoelectron spectroscopy and quantum dynamics study

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1063/1.4938423
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Name affiliation
  1. National Research Council of Canada
  2. National Research Council of Canada. NRC Steacie Institute for Molecular Sciences
  3. National Research Council of Canada. Security and Disruptive Technologies
FormatText, Article
Journal titleThe Journal of Chemical Physics
ISSN0021-9606
Volume144
Issue1
Article number14309
Subjectcalculations; dynamics; photoelectron spectroscopy; photoelectrons; photoionization; photons; quantum theory; Rydberg states; wave packets; excitation wavelength; non-adiabatic dynamics; photoionization cross section; quantum dynamics calculations; three orders of magnitude; time-dependent Hartree method; time-resolved photoelectron spectroscopy; vibrational excitation; excited states
Abstract
The dynamics of N-methylpyrrole following excitation at wavelengths in the range 241.5-217.0 nm were studied using a combination of time-resolved photoelectron spectroscopy (TRPES), ab initio quantum dynamics calculations using the multi-layer multi-configurational time-dependent Hartree method, as well as high-level photoionization cross section calculations. Excitation at 241.5 and 236.2 nm results in population of the A2(πσ-) state, in agreement with previous studies. Excitation at 217.0 nm prepares the previously neglected B1(π3py) Rydberg state, followed by prompt internal conversion to the A2(πσ-) state. In contrast with the photoinduced dynamics of pyrrole, the lifetime of the wavepacket in the A2(πσ-) state was found to vary with excitation wavelength, decreasing by one order of magnitude upon tuning from 241.5 nm to 236.2 nm and by more than three orders of magnitude when excited at 217.0 nm. The order of magnitude difference in lifetimes measured at the longer excitation wavelengths is attributed to vibrational excitation in the A2(πσ-) state, facilitating wavepacket motion around the potential barrier in the N-CH3 dissociation coordinate.
Publication date
PublisherAIP Publishing
LanguageEnglish
Peer reviewedYes
NPARC number21277473
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