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Q: Fachverband Quantenoptik und Photonik

Q 63: Poster Ultrakalte Moleküle

Q 63.7: Poster

Donnerstag, 22. März 2007, 16:30–18:30, Poster C

Femtosecond Pump-Probe Experiments on Ultracold Molecules — •Terence Mullins¹, Wenzel Salzmann¹, Judith Eng¹, Magnus Albert¹, Roland Wester¹, Matthias Weidemüller¹, Andrea Merli², Steffan Weber², Franziska Sauer², Mateusz Plewicki², Fabian Weise², Ludger Wöste², and Albrecht Lindinger² — ¹Universität Freiburg, Hermann Herder Str.3, D-79104 Freiburg i. Br., Germany — ²Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany

We present details of femtosecond pump-probe experiments on ultra-cold Rb atoms. The atoms are trapped in a high density dark magneto-optical trap (MOT) [1] (10¹¹cm⁻³). MOT light photoassociated ground state molecules and colliding atom pairs are excited to bound molecular states with a femtosecond pump pulse, centered 75cm⁻¹ red of the D1 atomic transition. After a defined delay, which may be adjusted with respect to the pump pulse, the molecules are ionized with a femtosecond probe pulse. A quadrupole mass spectrometer selects Rb₂⁺ molecular ions. An increased ion signal, along with wavepacket oscillations, is observed when the pump pulse precedes the probe pulse. Propagation timescales suggest a two-photon transition to 5s5d states, consistent with the measured non-linear pump power dependence. The experimental requirements for pump-dump formation of ground state molecules [2,3] is discussed.

[1] C.G. Townsend et al., Phys. Rev. A, 53, 1702, 1996.

[2] C.P. Koch et al., Phys. Rev. A, 73, 043409, 2006.

[3] U. Poschinger et al., J. Phys. B, 39, 1001 2006.