In the present case, the electronic and vibrational symmetries of the final states in features B1-B17, a elec Γ and a vib Γ , are g + ∑ and πu, respectively. These states can only be observed if they mix with a state b that is FC-allowed for detachment from the anion, i.e. b vib Γ = g σ , thereby requiring that the excited electronic state HT-coupled to this state be of u ∏ symmetry. Our calculations (Table ) find that such an excited state resides 2.24 eV above the neutral ground state.