Broadband rotational spectroscopy

In the independent Max-Planck research group, we investigate molecules and molecular complexes to gain a deeper understanding of the interplay between structure and function, of molecular recognition governed by molecular recognition, and of the role of molecules under extreme conditions, such as in the interstellar medium. For achieving these goals, we focus both on method development and their application, in tight combination with sophisticated theoretical investigations. Our research interests can be roughly distributed into the three following directions:

Molecular Structure – from precise structure determination to molecular recognition

We use broadband rotational spectroscopy, which we apply and further develop in our laboratory, to investigate various aspects in the area of molecular structure and dynamics: We concentrate on questions concerning intramolecular dynamics, molecular recognition as well as the relationship between function and molecular structure, with a special emphasis on their chirality, as for example relevant for understanding olfaction. These activities are also embedded within the excellence cluster “The Hamburg Centre for Ultrafast Imaging”.

Chirality and cold molecules– Enantiomer differentiation, mixture analysis and precision measurements

Together with scientists from Harvard University, we could develop a new method based on broadband rotational spectroscopy to unambiguously assign the enantiomers of chiral molecules and their absolute handedness, and to quantitatively analyse complex chiral mixtures. Besides gaining a deeper understanding of molecular chirality, this technique has also the potential to become a powerful new analytical tool. In addition, we are currently commissioning a newly developed microwave spectrometer to study molecular effects that will only become visible at spectral resolutions below 1 kHz, such as the frequency difference between the two enantiomers arising from the parity-violating character of the weak interaction. These research activities go hand in hand with our method development and application in the area of cold, slow molecular beams.

Unraveling interstellar chemistry with broadband microwave spectroscopy and next-generation telescope arrays

Supported via an ERC Starting Grant 2014, we are currently developing a new research branch on astrochemistry. The goal of our research activities is to significantly advance the current knowledge of interstellar chemistry by discovering new classes of molecules in space and unraveling their key chemical processes. So far, mostly physical reasons have been investigated for observed variations in molecular abundances. We can now study the influence of chemistry on the molecular composition of the universe by combining new laboratory spectroscopy with pioneering telescope observations (such as the international Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile). More information can be found here (link zur ERC Unterseite).

For pursuing these activities, our laboratory is equipped with two operating, home-built broadband rotational spectrometers, a molecular beam machine equipped with Stark and microwave decelerators and a set of pulsed lasers (three Nd:YAG pump lasers, two tunable dye lasers as well as one tunable OPO/OPA infrared laser system). A third spectrometer, funded by the Deutsche Forschungsgemeinschaft, is currently being commissioned. It is based on a microwave cavity design and dedicated to precision measurements (see below). My group is also active in applying theoretical methods to increase our understanding of complex molecular spectra, such as the permutation-inversion group theory. Within the framework of the ERC Starting Grant, we are designing a new millimeter wave chirp spectrometer that will operate in the 75-110 GHz range and thus offers direct overlap with ALMA.