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PRAVEENKUMAR BOOPALACHANDRAN, SRIJAY S. RAJAN, MELISSA A. BAUDHUIN AND DOREEN G. LEOPOLD, Department of Chemistry, University of Minnesota, Minneapolis, MN 55455 .

We report the 488 and 514 nm anion photoelectron spectra of NbMo^-. R2PI spectroscopic studies have established that neutral NbMo has a ² _5/2 ground state and a short bond length . We find that the NbMo^- anion has a ^{1 +} ground state in which the "extra" electron occupies the (4d) bonding orbital, giving a 1 ²1 ⁴1 ⁴2 ² valence electron configuration. Thus, NbMo^- has a formal bond order of 6, and is isoelectronic with Mo₂. Low-lying excited states of NbMo (^{2 +}) and NbMo^- (³ ) are also observed. The spectra provide the electron affinity of NbMo, energies of the ^{2 +} and ³ excited states, vibrational frequencies in the anion and neutral molecule ground states and the ^{2 +} state, ² and ³ spin-orbit splittings, and (from Franck-Condon analyses) bond length measurements for the anion ground state and the observed excited states. These results are compared with previous anion photoelectron spectroscopic data for the Group 5/6 congeners VCr and VMo, and with density functional theory predictions.