Hamburg 2009 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 19: Spektroskopie in He-Tröpfchen
MO 19.1: Hauptvortrag
Donnerstag, 5. März 2009, 14:00–14:30, VMP 6 HS-F
Femtosecond spectroscopy of alkali-doped helium nanodroplets — •Marcel Mudrich1, Philipp Heister1, Martin Schlesinger2, Walter Strunz2, and Frank Stienkemeier1 — 1Physikalisches Institut, Universität Freiburg — 2Theoretische Quantenoptik, Technische Universität Dresden
Helium nanodroplets doped with alkali atoms and molecules are intriguing systems at the border between gas-phase and condensed matter systems. Upon femtosecond laser excitation, alkali molecules exhibit vibrational wave packet oscillations which are only weakly affected by the helium environment. Subsequent desorption of the molecules off the helium droplets then leads to undamped wave packet motions. This allows for high-resolution Fourier spectra of vibrational levels in the electronic ground and excited states, as demonstrated e. g. for Rb2 and Rb3. The absence of vibrational damping in the triplet ground state of K2 in contrast to damped wave packet motion in electronically excited states is discussed in the context of Landau′s critical velocity and frictionless motion in superfluid helium on the nano scale.