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MO: Molekülphysik

MO 17: Poster II

MO 17.5: Poster

Thursday, March 25, 2004, 14:00–16:00, Schellingstr. 3

Formation of homo- and heteronuclear alkali molecules on helium nanodroplets — •M. Mudrich¹, O. Bünermann², F. Stienkemeier², and M. Weidemüller¹ — ¹Physikalisches Institut, Universität Freiburg, 79104 Freiburg — ²Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld

We present excitation spectra of heteronuclear alkali dimers (LiCs and NaCs) and of different oligomer states of cesium and rubidium formed on superfluid helium nanodroplets. The beam of helium nanodroplets is created by supersonic expansion through a small nozzle (d=5 µm) at low temperature (T ≈ 20 K) and at high pressure (p≈ 80 bar). Different detection schemes (photoionization, laser-induced fluorescence and laser-induced beam depletion) are compared. Mass-selective photoionization reveals the formation of CsHe* exciplexes both at the D1 and D2 transition of the cesium atoms attached to helium clusters. Characteristic features in the cesium excitation spectrum are identified as Cs₃ trimer states. From the LiCs and NaCs excitation spectra we deduce constraints to ab initio potential curves.