Two-dimensional penning ionization electron spectroscopy of open-shell metallocenes: Outer valence ionic states of vanadocene and nickelocene

摘要

In order to investigate outer valence ionic states of open-shell metallocenes, we have applied two-dimensional collision-energy/electron-energy-resolved Penning ionization electron spectroscopy (2D-PIES) upon collision with metastable He*(2~3S) excited atoms as well as a high level ab initio molecular orbital calculation (the partial third-order quasiparticle theory of the electron propagator (P3)) to ionization from neutral ground states of vanadocene (~4A_(2g)) and nickelocene (~3A _(2g)). Assignments of observed Penning ionization electron/He I ultraviolet photoelectron spectra were consistent with the P3 calculation results for ionization of α and β spin electrons except for electron correlation bands observed by PIES. Negative collision energy dependence of partial Penning ionization cross-sections (CEDPICS) indicate attractive interaction with He*(2~3S) around the molecule. Results by model potential calculation utilizing Li(2~2S) instead of He*(2 ~3S) for interaction between He*(2~3S) and open-shell metallocenes do not explain the strong negative CEDPICS of the bands observed in PIES.