Stuttgart 2012 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 37: Atomic clusters
A 37.5: Vortrag
Donnerstag, 15. März 2012, 15:30–15:45, V57.05
Core level photoelectron spectroscopy on free mass-selected lead clusters at FLASH — •Jens Bahn1, Patrice Oelßner1, Michael Köther1, Christian Braun3, Volkmar Senz2, Steffen Palutke4, Bernd von Issendorff5, Gerd Ganteför3, Michael Martins4, Josef Tiggesbäumker1, and Karl-Heinz Meiwes-Broer1 — 1Institut für Physik, Universität Rostock — 2Institut für Biomedizinische Technik, Universität Rostock — 3Fachbereich Physik, Universität Konstanz — 4Institut für Experimentalphysik, Universität Hamburg — 5Fakultät für Physik, Universität Freiburg
The electronic structure forms the basis for understanding the physical and chemical properties of clusters. A promising method to study this issue is core-level photoelectron spectroscopy using the VUV free electron laser FLASH at DESY providing wavelengths down to 4.8 nm. Results on lead clusters feature size-dependent 5d and 4f core-level shifts and reveal a remarkable change of final state screening conditions due to a metal to nonmetal transition at cluster sizes about 20 atoms [Phys. Rev. Lett. 102, 138303 (2009)]. In recent experiments a hemispherical electron spectrometer has been utilized. It became possible to allocate electron signals to each micro pulse of FLASH with a time-resolved delay-line-detector. A sequence of cluster sizes can be probed by this approach. By study of 4f core-level of lead clusters the change of the gaussian line shape to a Doniach-Sunjic profile has been observed as function of size. The evolution of the line profiles can be understood as scattering processes in finite systems.