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SYD: Symposium Cluster
SYD 2: Cluster: Starke Bindungen
SYD 2.4: Vortrag
Montag, 16. März 1998, 16:45–17:00, R712
Ionization potentials of LinO and LinC clusters — •H. Weidele, P. Thoen, W. Bouwen, F. Vanhoutte, P. Lievens, and R.E. Silverans — Laboratorium voor Vaste-Stoffysica en Magnetisme, K.U. Leuven, Celestijnenlaan 200 D, B-3001 Leuven
Lithium monoxide and monocarbide clusters are produced by a laser vaporization source and detected by time-of-flight mass spectrometry. Photoionization efficiency curves are measured using photons with energies from 3 to 5.52 eV, and 6.4 eV provided by an optical parametric oscillator, a dye laser, and an ArF excimer laser. Ionization potentials of LinO and LinC (n = 2-70) are derived from the curves. The evolution of the ionization potentials as a function of cluster size shows clear steps at certain sizes n which are assigned to shell closings. Also an odd-even staggering up to n ≈40 is visible. These metallic characteristics are, however, not present for very small lithium monoxide and monocarbide clusters. Here, the binding mechanisms seem to be molecular-like rather than metallic. From Li3O and Li5C on the oxygen and carbon atom reveal an unusual stoichiometry disobeying the octet rule of elements of the 2nd period (“hypervalent" bonding).