Rostock 2019 – scientific programme
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A: Fachverband Atomphysik
A 2: Ultra-cold atoms and molecules I (joint session A/MO/Q)
A 2.1: Talk
Monday, March 11, 2019, 10:30–10:45, S HS 1 Physik
Quantum state-dependent reactive collisions of OH− with ultracold Rubidium in a hybrid trap — •Saba Zia Hassan1, Jonas Tauch1, Eric Endres1, Markus Nötzold2, Henry Lopez1, Bastian Höltkemeier1, Roland Wester2, and Matthias Weidemüller1 — 1Physikalisches Institut Heidelberg, INF 226, 69120 Heidelberg — 2Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck
The study of ion-molecule reactions plays a vital role in cold chemistry, implying the need of well-controlled ion ensembles in a cold environment. The internal and external degrees of freedom of molecular ions, trapped in multipole radio frequency ion traps, can be cooled via collisions, with pre-cooled neutral atoms, to cryogenic temperatures of about 4 K. This lower temperature limit can be overcome using a laser-cooled buffer-gas localized at the center of the ion cloud.
In our hybrid atom-ion trap, the hydroxyl anions are stored in a 8-pole radio frequency wire trap and a dense cloud of ultracold rubidium is confined in a dark spontaneous-force optical trap (Dark-SPOT). The overlap of atoms and anions leads to elastic and inelastic collisions, cooling the external and internal degrees of freedom respectively. However, losses via associative detachment between OH− and rubidium also occur, as predicted by ab-initio calculations. By varying the ratio of excited to ground state atoms, quantum state-dependent reactive collisions can be studied. Accurate measurements of these reactions can allow us to probe into the effective core potentials used in theoretical studies. In this contribution the latest results will be presented.