title: High-resolution threshold photoelectron study of the propargyl radical by the vacuum ultraviolet laser velocity-map imaging method.
abstract: By employing the vacuum ultraviolet (VUV) laser velocity-map imaging (VMI) photoelectron scheme to discriminate energetic photoelectrons, we have measured the VUV-VMI-threshold photoelectrons (VUV-VMI-TPE) spectra of propargyl radical [C(3)H(3)(X̃(2)B(1))] near its ionization threshold at photoelectron energy bandwidths of 3 and 7 cm(-1) (full-width at half-maximum, FWHM). The simulation of the VUV-VMI-TPE spectra thus obtained, along with the Stark shift correction, has allowed the determination of a precise value 70 156 ± 4 cm(-1) (8.6982 ± 0.0005 eV) for the ionization energy (IE) of C(3)H(3). In the present VMI-TPE experiment, the Stark shift correction is determined by comparing the VUV-VMI-TPE and VUV laser pulsed field ionization-photoelectron (VUV-PFI-PE) spectra for the origin band of the photoelectron spectrum of the X̃(+)-X̃ transition of chlorobenzene. The fact that the FWHMs for this origin band observed using the VUV-VMI-TPE and VUV-PFI-PE methods are nearly the same indicates that the energy resolutions achieved in the VUV-VMI-TPE and VUV-PFI-PE measurements are comparable. The IE(C(3)H(3)) value obtained based on the VUV-VMI-TPE measurement is consistent with the value determined by the VUV laser PIE spectrum of supersonically cooled C(3)H(3)(X̃(2)B(1)) radicals, which is also reported in this article.
authors.affiliation: Department of Chemistry, University of California, Davis, California 95616, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Gao
authors.forename: Yuntao
authors.initials: Y
authors.lastname: Xu
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.forename: Chow-Shing
authors.initials: CS
authors.lastname: Lam
authors.forename: Hailing
authors.initials: H
authors.lastname: Wang
authors.forename: Jingang
authors.initials: J
authors.lastname: Zhou
authors.forename: C Y
authors.initials: CY
authors.lastname: Ng