Electronic structure of the diatomic VO anion: A combined photoelectron-imaging spectroscopic and theoretical investigation

Abstract

The electronic structure of the diatomic VO anion was explored by combining the photoelectron-imaging spectroscopy and high-level theoretical calculations. The electron affinity (EA) of VO is determined to be 1.244 \ifmmode\pm\else\textpm\fi{} 0.025 eV from the vibrationally resolved photoelectron spectrum acquired at 532 nm. The anisotropy parameter (\ensuremath{\beta}) for the EA defined peak is measured to be 1.59 \ifmmode\pm\else\textpm\fi{} 0.02, indicating that it is the 9\ensuremath{\sigma} electron attachment leading to the formation of the ground state of $\mathrm{V}{\mathrm{O}}^{\ensuremath{-}}$. The present imaging experiment provides direct evidence that the ground state of $\mathrm{V}{\mathrm{O}}^{\ensuremath{-}}$ is $X\phantom{\rule{0.16em}{0ex}}{}^{3}{\mathrm{\ensuremath{\Sigma}}}^{\ensuremath{-}}$ with a ${(3\ensuremath{\pi})}^{4}{(8\ensuremath{\sigma})}^{2}{(9\ensuremath{\sigma})}^{2}{(1\ensuremath{\delta})}^{2}$ electron configuration, which resolves the significant discrepancy in previous experiment and theory. In addition, the molecular orbitals and bonding involved in the anionic VO cluster are also examined based on the present high-level theoretical calculations.