title: Excited state non-adiabatic dynamics of N-methylpyrrole: A time-resolved photoelectron spectroscopy and quantum dynamics study.
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.
authors.affiliation: National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada.
authors.forename: Guorong
authors.initials: G
authors.lastname: Wu
authors.affiliation: Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Simon P
authors.initials: SP
authors.lastname: Neville
authors.affiliation: National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada.
authors.forename: Oliver
authors.initials: O
authors.lastname: Schalk
authors.affiliation: Department of Applied Physics, Hokkaido University, Kita-13 Nishi-8, Kita-ku, Sapporo 060-8628, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Sekikawa
authors.affiliation: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.
authors.forename: Michael N R
authors.initials: MN
authors.lastname: Ashfold
authors.affiliation: School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: Graham A
authors.initials: GA
authors.lastname: Worth
authors.affiliation: National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada.
authors.forename: Albert
authors.initials: A
authors.lastname: Stolow