Heidelberg 2015 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 22: Ultra-cold atoms, ions and BEC III (with Q)

A 22.7: Vortrag

Mittwoch, 25. März 2015, 12:30–12:45, M/HS1

Reactive collisions of Ba⁺ and Rb — •Joschka Wolf, Artjom Krükow, Amir Mohammadi, Amir Mahdian, and Johannes Hecker Denschlag — Universität Ulm, Institut für Quantenmaterie, Albert-Einstein-Allee 45, D-89069 Ulm, Deutschland

We investigate the reactive collisions of a laser-cooled trapped ¹³⁸Ba⁺ ion, with an ultracold cloud of optically trapped ⁸⁷Rb atoms. At atom densities of 10¹¹−10¹² we observe a quadratic density dependence of the ion loss rate, indicating three body-recombination of the ion with two Rb atoms. We do not observe two-body charge transfer, in contrast to other measurements, see [1] or [2]. We have also studied the dependence of the reaction rates in terms of collision energies. The rate constant for three body recombination scales as K₃ ∝ E^{−(0.5 ± 0.1)}, which is in rough agreement with a prediction of the group of Chris Greene. Interestingly, we do not observe molecular ions as reaction products after three-body recombination. However, we have some evidence that secondary reactions occur, which might lead to molecular dissociation.

[1] Zipkes et al, PRL 105, 133201 (2010) [2] Haze et al, arxiv 1403.5091 (2014)