Rostock 2019 – scientific programme
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MO: Fachverband Molekülphysik
MO 14: Ultrafast Multidimensional and Control Approaches
MO 14.5: Talk
Wednesday, March 13, 2019, 15:00–15:15, S HS 001 Biologie
Excited state Rabi-cycling near the ionization threshold after multiphoton excitation - a general concept? — •Tom Ring, Hendrike Braun, Alexander Kastner, Constantin Witte, Han-gyeol Lee, Arne Senftleben, and Thomas Baumert — Universität Kassel, Institut für Physik und CINSaT, 34132 Kassel, Germany
Control schemes using ultrashort laser pulses in the weak field regime such as the basic In behaviour and spectral interference as well as in the strong field regime such as Rabi-cycling, rapid adiabatic passage, photon locking or selective polpulation of dressed states are well established. The excitation of molecules and atoms with near infrared femtosecond laser pulses can merge these regimes: In many cases the first excitation step is predominantly non-resonant (weak field interaction) while the increasing density of states near the ionization threshold results in the possibility of subsequent one-photon absorptions which can lead to excited state Rabi-cycling (strong field interaction).
To investigate coherent dynamics of atoms and molecules in this combination region we employ 2d strong field spectroscopy using sequences of phase modulated femtosecond laser pulses. Varying the relative optical phase and the temporal separation between adjacent pulses allows to look at the coherent response of the atomic level as well as molecular systems in the form of electronic coherences. Comparison of our experimental results with simulations confirms the subsequent weak and strong field behaviour.