Interpretation of the photoelectron spectra of superalkali species: Li3O and Li3O-.

The present paper deals with the interpretation of the photoelectron spectrum of the Li(3)O(-). After several failed attempts to attribute all of the observed peaks in the experimental spectrum to anionic species, neutral species were considered assuming a sequential two-photon absorption mechanism. We find that only two of the six observed peaks can be attributed to photodetachments and that all other observed features can be assigned to ionizations from the ground and excited states of the neutral. Nuclear distributions other than three lithium atoms surrounding the oxygen are not likely to be stable. The interpretation of the experimental peak located at about 1.2 eV remains challenging. It can either be attributed to the second electron detachment (involving the HOMO -1 orbital) energy from the anion's triplet C(2v) state or to higher excited states (involving HOMO +10, 11, 12... orbitals) of the neutral species. Furthermore, we have examined the influence of vibrational displacements on the location of the observed peaks. We find that this effect is smaller than 0.05 eV and, therefore, must be considered as negligible.