Negative ion photoelectron spectroscopy of the group 5 metal trimer monoxides V₃O, Nb₃O, and Ta₃O

The ground and low-lying electronic states of group 5 clusters were discussed using vibrationally resolved 488 nm negative ion photoelectron spectra of V₃O, Nb₃O, and Ta₃O. The electron affinities, symmetric vibrational frequencies and normal mode displacements, and excited energies were measured using the photoelectron spectroscopy. It was found that the extra electrons in the anions occupy nonbonding orbitals and anionic clusters have planar structures with doubly bridging oxygen atoms.