Title: Manipulation of molecules with broadband laser: vibrational cooling and state conversion Speaker: Ridha Horchani Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, France Time: Thursday, February 2nd, 15.15 to 16.00 Place: Phys. Aud. Abstract: Cold molecules in the microkelvin-range can only been achieved starting with cold atoms. The method of producing cold molecules from cold atoms via photoassociation leads to the production of molecules in the ground state but in several vibrational levels. For additional applications, a major challenge is in the preparation, trapping and control of molecules in the ground vibrational and rotational state. The vibrational cooling through optical pumping using a shaped broadband femtosecond laser has been demonstrated for Cs2 molecules [1]. The molecules are initially formed in several vibrational levels, v, of the singlet ground state. A broadband femtosecond laser can electronically excite the molecules, leading via a few absorption - spontaneous emission cycles, to a redistribution of the vibrational population in the ground state. By removing the laser frequencies corresponding to the excitation of the v=0 level, we realize a dark state for the so-shaped femtosecond laser, yielding with the successive laser pulses to an accumulation of the molecules in the v=0 level, meaning vibrational cooling. The method of optical pumping using a shaped broadband laser is expected to be generally applicable to many molecular samples. The efficiency will depend on the relative strength of the transitions between vibrational levels of the concerned pairs of (ground-excited) electronic states. Recent developments of the method for targeting different vibrational levels [2] and for using a broadband incoherent light source [3] will be reported. The ongoing experiments devoted to the possibility for extending this method to rotational cooling will be discussed. Recent results of selective ionization spectroscopy of ground state molecular levels will also be presented. [1]. M. Viteau, A. Chotia, M. Allegrini, N. Bouloufa, O. Dulieu, D. Comparat and P. Pillet, Science 321, 232 (2008). [2]. D. Sofikitis, S. Weber, A. Fioretti, R. Horchani, M. Allegrini, B. Chatel, D. Comparat and P. Pillet, New J. Phys. 11, 055037 (2009). [3]. D. Sofikitis, R. Horchani, X. Li, M. Pichler, M. Allegrini, A. Fioretti, D. Comparat and P. Pillet, Phys. Rev. A 80 (5), 051401 (2009). Jacob Sherson and Aurélien Dantan Coffee, tea and cake will be served at 15.05 ----------------------------------- Aurelien Dantan Ion Trap Group Department of Physics and Astronomy University of Aarhus Ny Munkegade, bygn. 1520 8000 Aarhus Denmark +4589423602