title: Photoionization of propargyl and bromopropargyl radicals: a threshold photoelectron spectroscopic study.
abstract: In this Article, we present mass-selected threshold photoelectron spectra of propargyl as well as the 1- and 3-bromopropargyl radicals. The reactive intermediates were produced by flash pyrolysis of suitable precursors and ionized by VUV synchrotron radiation. The TPES of the propargyl radical was simulated using data from a recent high-level computational study. An ionization energy (IE) of 8.71 ± 0.02 eV was obtained, in excellent agreement with computations, but slightly above previous experimental IEs. The pyrolysis of 1,3-dibromopropyne delivers both 1- and 3-bromopropargyl radicals that can be distinguished by their different ionization energies (8.34 and 8.16 eV). To explain the vibrational structure, a Franck-Condon simulation was performed, based on DFT calculations, which can account for all major spectral features. Bromopropargyl photoionizes dissociatively beginning at around 10.1 eV. Cationic excited states of 1- and 3-bromopropargyl were tentatively identified. The dissociative photoionization of the precursor (1,3-dibromopropyne) was also examined, delivering an AE(0K) (C(3)H(2)Br(+)/C(3)H(2)Br(2)) of 10.6 eV.
authors.affiliation: Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Hemberger
authors.forename: Melanie
authors.initials: M
authors.lastname: Lang
authors.forename: Bastian
authors.initials: B
authors.lastname: Noller
authors.forename: Ingo
authors.initials: I
authors.lastname: Fischer
authors.forename: Christian
authors.initials: C
authors.lastname: Alcaraz
authors.forename: Bárbara K
authors.initials: BK
authors.lastname: Cunha de Miranda
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Garcia
authors.forename: Héloïse
authors.initials: H
authors.lastname: Soldi-Lose