Search

We report on the production of small and medium size lithium and lithium oxide clusters by a laser vaporization cluster source. The isotopomeric distribution of natural lithium allowed to identify LikO clusters as the most abundant components in the mass spectrum. Photoionization efficiency curves of LikO clusters with photon energies from 3.4 to 4.7 eV were measured for 8 ≤ k ≤ 27. Using linear extrapolation of the increase in photoionization efficiency with photon energy, ionization potentials were extracted. With the chemical bond of the O2- anion to two Li atoms, leaving n = k-2 valence electrons in the (Li2O)Lin clusters, clear shell closure effects are present at n = 8 and n = 20.

We report on the measurement of ionization potentials of lithium monoxide and lithium monocarbide clusters by threshold laser ionization spectroscopy. The clusters are produced by a laser vaporization source, mass selected, and detected by a reflectron time-of-flight mass spectrometer. The values obtained for the ionization potentials of the small clusters are consistent with hypervalent molecular bonding mechanisms. For the larger clusters the evolution of the ionization potentials with size is in agreement with metallic behavior as evidenced by several distinct steps and a pronounced odd-even staggering superposed on a smoothly decreasing trend. The steps in the ionization potentials correspond to the magic numbers predicted by cluster shell models (2, 8, 20, 40,…), provided that n−2, respectively n−4, electrons are delocalized in the clusters LinO and LinC.

Lithium clusters doped with carbon atoms are studied by threshold photoionization spectroscopy and ionization potentials are deduced for Li n C ( n ⩽70). The evolution of the ionization potentials with size shows distinct steps at n =24 and n =44, suggesting metallic behavior with n −4 free electrons in the larger clusters. Deviations from the metal-like behavior for the size range n

We report on a combined experimental and theoretical investigation of the ionization potentials of small lithium monocarbide clusters. The clusters were produced by a laser vaporization source, and their ionization potentials were measured by threshold photoionization spectroscopy. The structures of the smaller clusters (n≤8), which are governed by hypervalent (hyperlithiated) bonding mechanisms, were calculated by means of density functional theory. Vertical and adiabatic ionization potentials were computed and compared with the experimental data.