Electronic Transition Of Ferrocenium: Neon Matrix And Caspt2 Studies

Electronic absorptions of ferrocenium starting at 632.5 nm were measured in a 6 K neon matrix following mass selective deposition of the ions. The spectrum shows clear vibrational structure and provides the best-yet resolved view of the electronic states of this cation. The absorption system is identified as the 1 E-2(1)' <- X E-2(2)' transition (D-sh symmmetry) on the basis of vertical excitation energies and oscillator strengths calculated at the CASPT2 level. Vibrational bands in the spectrum are assigned with the aid of the ground-state frequencies calculated with the DFT method.