E. Tiemann's Research Group

Molecular Spectroscopy
The focus of our group is on experiments that allow for description of the interaction between atoms and molecules. We are interested in descriptions of cold collisions of atoms as well as in binding properties of molecules since both aspects can be related closely by molecular potentials. Our high precision spectroscopic experiments on particle beams enable us to determine these potentials from which we can deduce for example the scattering length with a higher resolution than in many other experiments. As the scattering length is of high importance for BEC experiments, our group has investigated methods to manipulate it in a desired way by magnetic or light fields.

Stark deceleration of molecules
The new experiment used time dependent and inhomogeneous electric fields to produce cold molecules in well specified quantum states and control their external degree of freedom. After a successful implementation of a prototype Stark decelerator for SO₂ molecules, the real machine was constructed. The 2 m long decelerator can stop the molecules and produces first results. The cold SO₂ molecules will be used for cold collision and cold reaction studies.

Iodine as a Secondary Frequency Standard
The experiments on iodine molecules lead to the development of a secondary frequency standard: Detailed analysis of Iodine spectra in selected wavelength intervals allowed to develop a physical model, which simulates the entire visible and near-infrared spectrum. Such spectra can be recorded along with an experimental scan in order to derive a frequency scale.

Cold Molecules
The often-applied cooling techniques for atoms cannot be applied for molecules due to the lack of closed cooling cycles. However, cold molecules can be formed in photoassociation from cold, trapped atoms. Our group is involved in an experiment that investigates the photoassociation of Calcium. The experiment is carried out in collaboration with the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig.

For details of our experiment see the Research page and the list of our Publications.

Teaching
A Fortgeschrittenen Praktikum II experiment can be performed in our group. It shows nicely the principles of high precision laser spectroscopy. For photos and details see the Teaching page. You will also find details on seminars held in recent semesters for students that including the possibility for a certificate (Schein).

Open positions
If you are interested in a Diploma thesis or a PhD position make sure to visit the Open Positions page.

Collaborations
We work in a number of (international) collaborations. These are listed on the Collaborations page.