'International Symposium on Molecular Spectroscopy'
Abstract
The 488 nm vibrationally-resolved photoelectron spectra of NbWβ and W2ββ are reported. The electron affinity of W2β ( 1Sigmagβ+leftarrow2Sigmauβ+ ) is found to be 1.118 pm 0.007 eV, which differs from the value reported in a previous anion photoelectron spectroscopic study of W2ββ (1.46 eV)footnote{H. Weidele et al., Chem. Phys. Lett. 237 (1995) 425-431}, but was accurately predicted by density functional calculations (1.12 eV)footnote{Z. J. Wu, X. F. Ma, Chem. Phys. Lett. 371 (2003) 35-39}. The fundamental vibrational frequency of W2β is measured to be 345 pm 15 wn, in agreement with the value previously reported in matrix resonance Raman studies (337 wn)footnote{Z. Hu, J.-G. Dong, J. R. Lombardi, D. M. Lindsay, J. Chem. Phys. 97 (1992) 8811-8812}. The W2ββ anion is measured to have a fundamental frequency of 320 pm 15 wn. Several weak transitions to excited electronic states are seen and tentatively assigned based on calculated energies. NbW has an electron affinity of 0.856 pm 0.007 eV. Vibrational frequencies are found, by Franck-Condon fitting of overlapping transitions, to be 365 pm 20 cmβ1 for NbWβ and 410 pm 20 cmβ1 for NbW. This increase in vibrational frequency upon photodetachment suggests that the extra electron is in an antibonding orbital, leading to ground state assignments of 3Delta and 2Delta for the anion and neutral, respectively. These results are compared to those obtained for other Group V and Group VI transition metal dimers and trends are discussed