title: Structural evolution, sequential oxidation, and chemical bonding in tritantalum oxide clusters: Ta(3)O(n)(-) and Ta(3)O(n) (n = 1-8).
abstract: We report a combined photoelectron spectroscopy (PES) and density functional theory (DFT) study on a series of tritantalum oxide clusters, Ta(3)O(n)(-). Well-resolved PES spectra are obtained for Ta(3)O(n)(-) (n = 1-8) at several detachment photon energies, yielding electronic structure information which is used for comparison with the DFT calculations. A trend of sequential oxidation is observed as a function of O content until Ta(3)O(8)(-), which is a stoichiometric cluster. Extensive DFT calculations are performed in search of the lowest energy structures for both the anions and neutrals. The first three O atoms are shown to successively occupy the bridging sites in the Ta(3) triangle. The next three O atoms each occupy a terminal site, with the seventh and eighth O atoms forming a double-bridge and a double-terminal, respectively. The Ta(3)O(7)(-) anion is found to possess a localized electron pair on a single Ta center, making it an interesting molecular model for Ta(3+) surface sites. Molecular orbital analyses are performed to elucidate the chemical bonding in the Ta(3)O(n)(-) clusters.
authors.affiliation: Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99354, USA.
authors.forename: Hua-Jin
authors.initials: HJ
authors.lastname: Zhai
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang