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A: Atomphysik

A 4: Clusters I: Metal Clusters (joint session A and MO)

A 4.3: Talk

Monday, April 2, 2001, 16:15–16:30, H1012

K^*He_n Exciplex Formation on the Surface of Helium Nanodroplets Studied in Real-time — •F. Stienkemeier¹, D. Schumacher¹, P. Claas¹, and C.P. Schulz² — ¹Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, D-33615 Bielefeld, Germany — ²Max-Born-Institut, Max-Born-Str. 2a, D-12489 Berlin, Germany

Superfluid helium nanodroplets are doped with potassium atoms to form complexes with the alkali atom residing on the surface of the droplets. Dispersed laser-induced fluorescence spectra of such systems already revealed the formation of M^*He (M=Na,K) exciplexes upon electronic excitation [1]. By means of femtosecond pump-probe spectroscopy this formation process now is followed in real time. We find K^*He_n=1 to be formed within 170 fs. Furthermore, the existence of exciplexes with n > 1 is quantified suggesting the first ring around the potassium atom consisting of 4 helium atoms.

[1] Reho et al., Faraday Discuss. 108, 161 (1997).