VIBRATIONAL STRUCTURE OF LIGATED NIOBIUM CLUSTERS: PULSED FIELD IONIZATION ZERO KINETIC ENERGY PHOTOELECTRON SPECTROSCOPY AND DENSITY FUNCTIONAL THEORY CALCULATIONS
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Date
1995
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Publisher
Ohio State University
Abstract
Pulsed field ionization-zero kinetic energy photoelectron spectroscopy (PFI-ZEKE) is employed to probe vibrational structure of niobium cluster oxide $(Nb_{3}O/Nb_{3}O^{+})$, carbide $(Nb_{3}C_{2}/Nb_{3}{C_{2}}^{+})$, and nitride$(Nb_{3}N_{2}/Nb_{3}{N_{2}}^{+})$ in gas phase. For the niobium cluster oxide, vibrationally resolved PFI-ZEKE spectrum of the ion ground state is presented with a resolution of ${\sim} 3 cm^{-1}$. Density functional theory calculations are performed to obtain full geometry optimization and harmonic vibrational frequencies of the neutral and the ion. Spectral analyses with the aid of the theoretical calculations show three normal modes of $Nb_{3}O/Nb_{3}O^{+}$ observed in our PFI-ZEKE experiments. They are the symmetric bending of $Nb-Nb-Nb(\nu_{3})$, asymmetric strectching of $Nb-Nb(\nu_{5})$, and twisting of $Nb3O(\nu_{6})$ in the most stable planar structure. For the niobium cluster carbide and nitride, vibrationally resolved spectra have also been obtained. Spectral analyses are in progress.
Description
Author Institution: National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6; Université de montréal, C.P. 6128, Succursale Centre Ville, Montréal, Québec, Canada H3C 3J7