Molecules and Lasers
Molecules are manipulated in their internal and external degrees of freedom using lasers and electric fields to provide high precision spectroscopic data, to decelerate them or to implement a Ramsey-Bordé interferometer that makes use of their wave-nature. Permanent and transition dipole moments, cold collision cross sections and very accurate potential energy surfaces can be determined by means of these techniques.
Research areas of our group (details below):
Molecular Spectroscopy & Long Range Interactions
These experiments allow for description of the interaction between atoms and molecules. We are interested in 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. More
Iodine as a Secondary Frequency Standard
The experiments on iodine molecules have led to the development of a versatile secondary frequency standard based on the precisely known iodine spectrum: Detailed analysis of I2 spectra and data from literature allowed to develop physical models, which allow to simulate the entire visible and near-infrared spectrum. Such spectra, recorded along with experimental spectra of e.g. another molecule, can be used to derive a frequency scale with a precision of few MHz in certain spectral regions. More
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.