Hannover 2013 – scientific programme
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A: Fachverband Atomphysik
A 7: Interaction with VUV and X-ray light I
A 7.1: Talk
Monday, March 18, 2013, 14:00–14:15, B 302
EUV Ionization of Bare and Alkali Doped Helium Nanodroplets — •D. Buchta1, S.R. Krishnan2, N. Brauer3, C. Callegari4, M. Coreno4, K. Prince4, P. O'Keeffe5, F. Stienkemeier1, R. Moshammer2, and M. Mudrich1 — 1Physikalisches Institut, Universität Freiburg, D-79104 Freiburg im Breisgau — 2Max-Planck-Institut für Kernphysik, D-69117 Heidelberg — 3Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne, CH-1015 Lausanne — 4Sincrotrone Trieste, I-34149 Basovizza — 5CNR Istitudo di Metodologie Inorganiche e dei Plasmi, I-00016 Monterotondo Scalo
He nanodroplets are widely used as a cold and weakly interacting matrix for spectroscopy of embedded species. In this work we excite or ionize the He droplets using synchrotron radiation and study the back action onto the impurity atoms. Using photoelectron-photoion coincidence imaging spectroscopy at variable photon energies (20-25eV), we compare charge-transfer to Penning ionization of impurities located inside the droplets (rare gases) and those located at the droplet surface (alkali metals). The surprising finding is that alkali metals are very efficiently Penning ionized upon excitation of the 1s2p-band of He droplets, in contrast to rare gases. This speaks for rapid exciton migration to the surface, followed by relaxation and eventually the energy transfer to the alkali impurity.