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

Journal Article · Thu Jan 07 00:00:00 EST 2016 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4938423· OSTI ID:22493619

Wu, Guorong ^[1]; Neville, Simon P. ^[2]; Schalk, Oliver ^[1]; Sekikawa, Taro ^[3]; Ashfold, Michael N. R. ^[4]; Worth, Graham A. ^[5]; Stolow, Albert ^[1]

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1. National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada)
2. Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada)
3. Department of Applied Physics, Hokkaido University, Kita-13 Nishi-8, Kita-ku, Sapporo 060-8628 (Japan)
4. School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)
5. School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

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 A{sub 2}(πσ{sup ∗}) state, in agreement with previous studies. Excitation at 217.0 nm prepares the previously neglected B{sub 1}(π3p{sub y}) Rydberg state, followed by prompt internal conversion to the A{sub 2}(πσ{sup ∗}) state. In contrast with the photoinduced dynamics of pyrrole, the lifetime of the wavepacket in the A{sub 2}(πσ{sup ∗}) 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 A{sub 2}(πσ{sup ∗}) state, facilitating wavepacket motion around the potential barrier in the N–CH{sub 3} dissociation coordinate.

• OSTI ID: 22493619
• Journal Information: Journal of Chemical Physics, Vol. 144, Issue 1; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COORDINATES
CROSS SECTIONS
DISSOCIATION
EXCITATION
INTERNAL CONVERSION
LAYERS
LIFETIME
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
POTENTIALS
PYRROLES
RYDBERG STATES
TIME DEPENDENCE
TIME RESOLUTION
WAVE PACKETS
WAVELENGTHS