Berlin 2005 – wissenschaftliches Programm
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A: Atomphysik
A 16: Atomic Clusters and Cold Atoms II
A 16.6: Fachvortrag
Mittwoch, 9. März 2005, 11:30–11:45, HU 3075
Post-Collision Interaction of Free Van der Waals Clusters — •Ioana L. Bradeanu1, Hiroyuki Setoyama2, Takaki Hatsui3, Nobuhiro Kosugi2, and Eckart Rühl1,2 — 1Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — 2Institute for Molecular Science, Myodaiji, Okazaki, 444-8585, Japan — 3The Graduate University for Advanced Studies, Myodaiji, Okazaki, 444-8585, Japan
The line shapes of photoelectron spectra of atoms and molecules depend in the core-level excitation regime strongly on the core hole lifetime. In the regimes above the core ionization energies there is additional asymmetric broadening, which is due to the interaction between the photoelectron and the Auger electrons. This is commonly known as post-collision interaction (PCI). PCI is investigated in free, variable size krypton and argon clusters near the Kr3d-and Ar2p-ionization energies. The experimental photoelectron spectra are fitted by using a formalism which is known to be valid even close to core ionization thresholds of atoms. The peak shapes are convoluted with a Gaussian in order to account for the experimental resolution. It is found that the asymmetry, which is due to PCI, is characteristically smaller for clusters than for isolated atoms. Moreover, there is less asymmetry for bulk-sites than for surface-sites in variable size rare gas clusters. We rationalize these results in terms of a mechanism, which is based on the classical model of post-collision interaction.