Dear All, On monday and tuesday next week there will be two AMO-seminars. Since the first seminar is on monday morning, you receive this reminder already today. Abstracts follow below. Hope to see you! \Peter. --------------------------------------------------------- Speaker: Stefan Willitsch Departement Chemie, Universität Basel, Switzerland Title: Cold chemical reactions with laser- and sympathetically cooled ions in ion traps Time: Monday, October 26, 10.15 to 11.00 Place: Fysisk Auditorium Abstract: The recent progress in the generation of translationally cold atoms and molecules in the gas phase has enabled us to study chemical processes in a new physical regime. We have recently developed a novel experiment which takes advantage of the unusual properties of translationally cold, Coulomb-crystallised ions in ion traps to study reactive ion-neutral collisions at very low energies. Our setup combines a linear Paul trap for the laser- and sympathetic cooling of atomic and molecular ions with a quadrupole-guide velocity selector for the generation of translationally cold neutrals at kinetic energies of Ekin/kB?1 K. In the talk we review recent results on selected reactions with cold atomic and molecular ions, discuss the features of our method and explore further developments towards fully quantum-state selected reactive collision experiments in the mK range. Peter Staanum and Nicolai Nygaard Coffee, tea and bread rolls will be served at 10.05 ------------------------------------------------------- Speaker: Olivier Dulieu, Laboratoire Aimé Cotton, CNRS, France Title: Electronic structure of alkali dimers and trimers. Prospects for alignment and orientation effects. Time: Tuesday, October 27, 10.15 to 11.00 Place: Fysisk Auditorium Abstract: The rapid development of experimental techniques to produce cold and ultracold molecules [1] opens the ways to manipulate them or to control their formation dynamics using external fields, and to explore their interactions with surrounding particles. In most cases, the detailed knowledge of the internal molecular structure is required to guide such studies and to interpret their results. For several years now our group carries out systematic theoretical investigations on alkali molecular systems, using a quantum chemistry approach based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective potentials for core polarization [2]. Potential curves and permanent and transition dipole moments have been obtained for all alkali pairs, both homonuclear and heteronuclear [2, 3], which are relevant for ultracold molecule formation processes. Calculations for ionic species like MgH+ have been also performed. The manipulation of polar bialkali molecules with electrostatic or strong off-resonant laser fields is governed by their dipole moment and their static polarizability. We computed the static dipole polarizability tensor for all bialkali pairs [4], and for alkali hydrides. We will present scenarios for the permanent alignment of ultra-cold heteronuclear molecules [4], based on combinations of static electric fields and strong laser fields [5]. Once ultracold molecular samples are dense enough, the interaction between atoms and molecules become observable [6]. We present preliminary results on the calculation of potential energy surfaces for heavy alkali trimers (Cs3) at arbitrary geometries and symmetries. Using effective core potentials, it is possible to carry out full configuration interaction calculations for the valence electrons and hence accurately take into account all electronic interactions [7]. Finally, we present a new investigation of the dynamics of the H2-H- complex, and discuss the possible formation of H3- in the interstellar medium [8]. [1] O. Dulieu and C. Gabbanini, Reports on Progress in Physics, 72, 086401 (2009) [2] M. Aymar and O. Dulieu, J. Chem. Phys. 122, 204302 (2005) [3] M. Aymar and O. Dulieu, Mol. Phys. 105, 1733 (2007) [4] J. Deiglmayr, M. Aymar, R. Wester, M. Weidemüller, and O. Dulieu, J. Chem. Phys. 129, 064309 (2008) [5] B. Friedrich and D. Herschbach, J. Phys. Chem. A 103, 10280 (1999) [6] N. Zahzam et al, Phys. Rev. Lett. 96, 023202 (2006) ; P. Stanuum et al, Phys. Rev. Lett. 96, 0232021 (2006); [7] R. Guérout, P. Soldan, M. Aymar, J. Deiglmayr, O. Dulieu, Int. J. Quant. Chem., 109, 3387 (2009) [8] V. Kokoouline, M. Ayouz, R. GuÍ©rout, M. Raoult, J. Robert, O. Dulieu, arXiv: physics.atom-ph/ 0910.2330 Peter Staanum and Nicolai Nygaard Coffee, tea and bread rolls will be served at 10.05 ------------------------------------------------------------------- ---------------------------------- Peter Frøhlich Staanum Department of Physics and Astronomy University of Aarhus Ny Munkegade 120 8000 Aarhus C Denmark Phone: (+45) 8942 3602 Fax: (+45) 8612 0740 VAT Nr.: DK16562777 EAN Nr.: 5798000419872 ----------------------------------