Hamburg 2009 – scientific programme

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A: Fachverband Atomphysik

A 37: Precision Spectroscopy of Atoms and Ions VII

A 37.4: Talk

Friday, March 6, 2009, 15:15–15:30, VMP 6 HS-B

Spectroscopy of Os⁻ and a Route to Laser-Cooled Negative Ions — •Ulrich Warring, Carlo Canali, Arne Fischer, and Alban Kellerbauer — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

Typical binding energies of negative ions are in the range of 1–2 eV, hence at least one order of magnitude lower than in positive ions or atoms. Furthermore the potential experienced by the valence electron is short-ranged and thus only supports a finite number of bound states. Often these bound states are different fine-structure levels of the same configuration. An exceptional case can be found in the negative osmium ion. It has the unique property of a bound excited state with opposite parity with respect to the ground state – so far the only known electric-dipole transition in a negative ion. This fact enables the use of standard atomic-physics techniques, such as laser cooling. The goal of the UNIC project (Ultracold Negative Ions by indirect laser Cooling) is to demonstrate this method to work. As a first milestone we conducted high-resolution laser spectroscopy of the relevant transition on a Os⁻ beam. In this presentation we will report on the experimental results and outline the next steps towards trapping and laser cooling negative osmium ions.