Rotationally Selected and Resolved State-to-State Photoelectron Study of Vanadium Monoxide Cation VO(+)(X(3)Σ(-); v(+) = 0-3).

Vanadium monoxide cation VO(+)(X(3)Σ(-)) has been investigated by two-color visible (VIS)-ultraviolet (UV) pulsed field ionization-photoelectron (PFI-PE) methods. The unambiguous rotational assignment of rotationally selected and resolved VIS-UV-PFI-PE spectra thus obtained confirms the ground state term symmetry of VO(+) to be X(3)Σ(-). The rotational analysis also yields the rotational constants Be(+) = 0.5716 ± 0.0012 cm(-1) and αe(+) = 0.0027 ± 0.0005 cm(-1) for VO(+)(X(3)Σ(-)), from which the equilibrium bond distance of VO(+)(X(3)Σ(-)) is determined to be re(+) = 1.557 ± 0.002 Å. This PFI-PE study covers the vibrational bands, VO(+)(X(3)Σ(-); v(+) = 0, 1, 2, and 3) ← VO(X(4)Σ(-); v″ = 0), which has made possible the determination of the vibrational constants for VO(+)(X(3)Σ(-)) to be ωe(+) = 1068.0 ± 0.7 cm(-1) and ωe(+)xe(+) = 5.5 ± 0.7 cm(-1). The present state-to-state measurement also yields a more precise value (58 380.0 ± 0.7 cm(-1) or 7.238 20 ± 0.000 09 eV) for the ionization energy of VO [IE(VO)]. This value along with the known IE(V) has allowed the determination of the difference between the 0 K bond dissociation energy (D0) of VO(+)(X(3)Σ(-)) and that of VO(X(4)Σ(-)) to be D0(V(+)-O) - D0(V-O) = IE(V) - IE(VO) = -3967 ± 1 cm(-1).