title: Rovibrationally selected and resolved pulsed field ionization-photoelectron study of propyne: ionization energy and spin-orbit interaction in propyne cation.
abstract: By using a high-resolution infrared (IR) laser to prepare propyne (C(3)H(4)) in selected rotational levels of the excited nu(1) (acetylenic C-H stretching) vibration mode prior to vacuum ultraviolet (VUV) laser pulsed field ionization-photoelectron (PFI-PE) measurements, we have obtained rotationally resolved VUV-PFI-PE spectra for the C(3)H(4) (+)(X (2)E(32,12),nu(1) (+)=1) band. The analysis of these PFI-PE spectra leads to the determination of the spin-orbit constant of A=-13.0+/-0.2 cm(-1) for the C(3)H(4) (+)(X (2)E(32,12),nu(1) (+)=1) state. Using this A constant and the relative rotationally selected and resolved state-to-state photoionization cross sections thus measured, we have obtained an excellent simulation for the VUV-PFI-PE origin band of C(3)H(4) (+)(X (2)E(32,12)), yielding a value of 83 619.0+/-1.0 cm(-1) (10.367 44+/-0.000 12 eV) for the adiabatic ionization energy of C(3)H(4) [IE(C(3)H(4))]. The present two-color IR-VUV-PFI-PE study has also made possible the determination of the C-H stretching frequencies nu(1) (+)=3217.1+/-0.2 cm(-1) for C(3)H(4) (+)(X (2)E(32,12)). The spectral assignment and simulation were guided by high-level ab initio calculations on the IE(C(3)H(4)), Franck-Condon factors for photoionization transitions, and rotational constants and vibrational frequencies for C(3)H(4) (+).
authors.affiliation: Department of Chemistry, University of California, Davis, California 95616, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Xing
authors.forename: Mi-Kyung
authors.initials: MK
authors.lastname: Bahng
authors.forename: Beth
authors.initials: B
authors.lastname: Reed
authors.forename: C S
authors.initials: CS
authors.lastname: Lam
authors.forename: Kai-Chung
authors.initials: KC
authors.lastname: Lau
authors.forename: C Y
authors.initials: CY
authors.lastname: Ng