title: Electronic structure and chemical bonding in MO(n)- and MO(n) clusters (M = Mo, W; n = 3-5): a photoelectron spectroscopy and ab initio study.
abstract: Photoelectron spectroscopy (PES) and ab initio calculations are combined to investigate the electronic structure of MO(n)- clusters (M = W, Mo; n = 3-5). Similar PES spectra were observed between the W and Mo species. A large energy gap between the first and second PES bands was observed for MO3- and correlated with a stable closed-shell MO3 neutral cluster. The electron binding energies of MO4- increase significantly relative to those of MO3-, and there is also an abrupt spectral pattern change between MO3- and MO4-. Both MO4- and MO5- give PES features with extremely high electron binding energies (>5.0 eV) due to oxygen-2p-based orbitals. The experimental results are compared with extensive density functional and ab initio [CCSD(T)] calculations, which were performed to elucidate the electronic and structural evolution for the tungsten oxide clusters. WO3 is found to be a closed-shell, nonplanar molecule with C3v symmetry. WO4 is shown to have a triplet ground state (3A2) with D2d symmetry, whereas WO5 is found to be an unusual charge-transfer complex, (O2-)WO3+. WO4 and WO5 are shown to possess W-O* and O2-* radical characters, respectively.
authors.affiliation: Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99352, USA.
authors.forename: Hua-Jin
authors.initials: HJ
authors.lastname: Zhai
authors.forename: Boggavarapu
authors.initials: B
authors.lastname: Kiran
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Cui
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.forename: David A
authors.initials: DA
authors.lastname: Dixon
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang