title: Rotationally resolved state-to-state photoionization and the photoelectron study of vanadium monocarbide and its cations (VC/VC(+)).
abstract: By employing two-color visible (VIS)-ultraviolet (UV) laser photoionization and pulsed field ionization-photoelectron (PFI-PE) techniques, we have obtained highly rotationally resolved photoelectron spectra for vanadium monocarbide cations (VC(+)). The state-to-state VIS-UV-PFI-PE spectra thus obtained allow unambiguous assignments for the photoionization rotational transitions, resulting in a highly precise value for the adiabatic ionization energy (IE) of vanadium monocarbide (VC), IE(VC) = 57512.0 ± 0.8 cm(-1) (7.13058 ± 0.00010 eV), which is defined as the energy of the VC(+)(X(3)Δ1; v(+) = 0; J(+) = 1) ← VC(X(2)Δ3/2; v'' = 0; J'' = 3/2) photoionization transition. The spectroscopic constants for VC(+)(X(3)Δ1) determined in the present study include the harmonic vibrational frequency ωe(+) = 896.4 ± 0.8 cm(-1), the anharmonicity constant ωe(+)xe(+) = 5.7 ± 0.8 cm(-1), the rotational constants Be(+) = 0.6338 ± 0.0025 cm(-1) and αe(+) = 0.0033 ± 0.0007 cm(-1), the equilibrium bond length re(+) = 1.6549 ± 0.0003 Å, and the spin-orbit coupling constant A = 75.2 ± 0.8 cm(-1) for VC(+)(X(3)Δ1,2,3). These highly precise energetic and spectroscopic data are used to benchmark state-of-the-art CCSDTQ/CBS calculations. In general, good agreement is found between the theoretical predictions and experimental results. The theoretical calculations yield the values, IE(VC) = 7.126 eV; the 0 K bond dissociation energies: D0(V-C) = 4.023 eV and D0(V(+)-C) = 3.663 eV; and heats of formation: ΔH°(f0)(VC) = 835.2, ΔH°(f298)(VC) = 840.4, ΔH°(f0)(VC(+)) = 1522.8, and ΔH°(f298)(VC(+)) = 1528.0 kJ mol(-1).
authors.affiliation: Department of Chemistry, University of California, Davis, CA 95616, USA. kaichung@cityu.edu.hk cyng@ucdavis.edu.
authors.forename: Yih Chung
authors.initials: YC
authors.lastname: Chang
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Luo
authors.forename: Yi
authors.initials: Y
authors.lastname: Pan
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Ying-Nan
authors.initials: YN
authors.lastname: Song
authors.forename: Sophie Yajin
authors.initials: SY
authors.lastname: Kuang
authors.forename: Qing Zhu
authors.initials: QZ
authors.lastname: Yin
authors.forename: Kai-Chung
authors.initials: KC
authors.lastname: Lau
authors.forename: C Y
authors.initials: CY
authors.lastname: Ng