Heidelberg 2015 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 11: Poster: Atomic clusters (with MO)

A 11.1: Poster

Montag, 23. März 2015, 17:00–19:00, C/Foyer

Radio-frequency buncher for core-level photoelectron spectroscopy of metal clusters at FLASH — •Franklin Martinez, Patrice Oelßner, Michael Köther, Josef Tiggesbäumker, and Karl-Heinz Meiwes-Broer — Universität Rostock, Institut für Physik, 18055 Rostock

XUV radiation of high brilliance from the free electron laser facility FLASH (Hamburg) allows to access electronic core levels of free metallic clusters by photo-electron spectroscopy (PES). Recent experiments on lead cluster anions revealed a systematic shift of 5d and of 4f level energies as a function of cluster size. For small clusters, a variation of the electron binding energy from the metallic sphere model due to reduced core-hole screening is observed [1,2]. However, with decreasing cluster size and also with increasing photon energies, the photoionization cross sections decrease rapidly, thus limiting the photo-electron yield. To increase the target density of size-selected clusters, and hence the electron yield, a new apparatus with a linear radiofrequency ion trap is currently under construction. Perspectively, the ion trap is to be combined with a radio-frequency ion buncher to increase the cluster density in the laser interaction region even further. With this setup many-electron dynamics due to x-ray photon absorption and highlycorrelated phenomena on ultrashort timescales in clusters will be addressed in future experiments. This contribution reports about design and simulations of the rf-buncher. The work is funded by the bmbf (FSP302), and supported by the DFG (SFB 652). [1] V. Senz et al., PRL 102, 138303 (2009). [2] J. Bahn et al., NJP 14, 075008 (2012).