Regensburg 2002 – wissenschaftliches Programm

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SYCO: Cluster auf Oberflächen

SYCO 4: Posters (will be on the whole day)

SYCO 4.6: Poster

Donnerstag, 14. März 2002, 18:45–19:30, H 36 Foyer

Influence of charge density fluctuations in metal clusters. — •Oleg Kidun and Jamal Berakdar — Max-Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle/Saale

This work demonstrates that the fluctuations of the electronic charge density of metallic clusters in response to an approaching electron suppress the single ionization channel. This is concluded from full numerical calculations for the electron-impact total ionization cross section using the random-phase approximation with exchange for the description of the particle-hole (de)excitations. Furthermore, we show that the numerical results can be qualitatively understood by means of the Thomas-Fermi model of screening. The present theoretical study offers a quantitative explanation of the behavior of the measured total ionization cross section for C60. In addition, we investigate the interplay between size and non-local screening effects by studying the lithium clusters with an different cluster radius radius and monitoring the influence of the particle-hole excitations. To disentangle correlation from exchange effects, we explore the differences in the ionization cross sections of metal clusters upon electron and proton impact. In the latter case, exchange effects are absent.