Study of Nb2Oy (y=2-5) anion and neutral clusters using anion photoelectron spectroscopy and density functional theory calculations

A study combining anion photoelectron spectroscopy and density functional theory calculations on the transition metal suboxide series, Nb2Oy- (y = 2-5), is described. Photoelectron spectra of the clusters are obtained, and Franck-Condon simulations using calculated anion and neutral structures and frequencies are used to evaluate the calculations and assign transitions observed in the spectra. The spectra, several of which exhibit partially resolved vibrational structure, show an increase in electron affinity with increasing cluster oxidation state. Hole-burning experiments suggest that the photoelectron spectra of both Nb2O2- and Nb2O3- have contributions from more than one structural isomer. Reasonable agreement between experiment and computational results is found among all oxides. (C) 2011 American Institute of Physics. [doi:10.1063/1.3634011]