Photoelectron spectroscopy of Ce(η-C5H5)3 – Accessing two ion states on 4f ionization

Valence PES have been measured for Ce(η-C5H5)3 in the gas phase with photon energies of 24–135 eV. Two ion states arising from ionization of the single 4f electron are unambiguously characterized by the intensity behaviour of the associated bands. Assignment is made using a VBCI model where purely ionic components are allowed to mix under configuration interaction. Thus the ground state of the [Ce(η-C5H5)3]+ cation is described as a mixture of two configurations of 1A1 symmetry, one with no 4f electron, Lf0 and one with a single 4f electron interacting strongly with a hole of the same symmetry in the ligand shell, L−1f1.