Hamburg 2001 – wissenschaftliches Programm
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O: Oberflächenphysik
O 25: Postersitzung (Grenzfl
äche fest-flüssig, Methodisches, Nanostrukturen, Organische Dünnschichten, Rastersondentechniken, reine Oberfl
ächen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie, Sonstiges)
O 25.66: Poster
Mittwoch, 28. März 2001, 15:00–18:00, Foyer zu B
Correlation effects in the production of the charged metal clusters. — •Oleg Kidun and Jamal Berakdar — Max Planck Institut für Mikrostrukturphysik, Halle/Saale
In this work we study the effect of electronic correlation on the ionisation of free and surface-deposited metallic clusters following the impact of low-energy electrons. The calculations of the quantum ground states of the clusters are performed within the Hartree-Fock and the jellium model. The effect of the cluster potential geometry is illustrated by employing various shapes of the potential well. The interaction between the incoming projectile electron and the metal cluster is described on the basis of random phase approximation with exchange, which leads to the concept of screening of the inter-electronic interaction. We compare the results of the calculation with available experimental data for the ionization of C60 by electron impact and show that the neglect of the correlation leads to results at variance with experimental finding. Furhtermore, we show that the electronic correlation results in a flattening of the total ionization cross section. As shown from a simple algebraic analysis, this effect can be traced back to the fact that for the unscreened Coulomb interaction the main contribution to the cross section originates from far-distance collisions whereas in case of screening there is a cut-off impact parameter beyond which the contribution of collisions to the cross section diminishes.