Berlin 2005 – wissenschaftliches Programm

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A: Atomphysik

A 16: Atomic Clusters and Cold Atoms II

A 16.3: Fachvortrag

Mittwoch, 9. März 2005, 10:45–11:00, HU 3075

UV-visible Fluorescence of 2p-excited argon clusters — •Roman Flesch¹, Ioana Bradeanu¹, Michael Meyer², and Eckart Rühl¹ — ¹Institut f. Physikalische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — ²L.U.R.E., Centre Universitaire Paris-Sud, Batiment 209D, F-91898 Orsay Cedex, France

Fluorescence of 2p-excited argon clusters in the wavelength range between 150 nm and 650 nm is measured by using for primary excitation tunable soft-X-ray undulator radiation between 240 eV and 270 eV at the UE-52-PGM beamline of the storage ring BESSY. Two complementary sets of experiments are performed: (a) Fluorescence yields show the highest intensity from clusters in the 2p-continuum. Weaker intensity comes from exciton formation in the pre-edge regime. Such shape of the fluorescence yield indicates that predominantly doubly charged argon clusters lead to emission of ultraviolet fluorescence photons; (b) Dispersed fluorescence spectra are recorded in the 200-600-nm range where the clusters are excited in the Ar 2p-continuum. A broad fluorescence continuum is found which is centered between 250 and 300 nm. The origin of this continuous emission is discussed with respect to possible relaxation mechanisms of core-excited clusters.