New Developments in High Resolution IR-Cavity ringdown Spectroscopy

• Applicants: Dr. Guido Fuchs; Professor Dr. Thomas Giesen
• Subject Area: Astrophysics and Astronomy ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 326572190

With this application we would like to strengthen our capabilities in performing experiments in molecular physics and laboratory astrophysics to produce and spectroscopically characterize molecules and to identify molecular signatures that are of relevance to astrophysical observations. To this end, we want to expand the experimental setup and introduce a new detection method that will enable us to use additional techniques for molecule production (e.g., laser ablation) and better investigate time-critical processes. A major application of these new laboratory investigations will be in the field of infrared astronomy. The project is timely as with new instruments like METIS (Mid-infrared ELT Imager and Spectrograph) on the currently constructed Extremely Large Telescope (ELT/ESO) in Chile spectrally high-resolution data will be abundantly available of diverse objects like warm molecular clouds, star formation regions, and exoplanets, but also late-type star environments. Even today’s telescopes like the VLT (e.g., using the CRIRES spectrograph) can profit from the availability of high-resolution IR spectra of molecules of astrophysical interest in the wavelength region 1.5 to 4 μm as is planned in this proposal. Key to the correct interpretation of astrophysically observed molecular data is the exact understanding of high-resolution spectra from laboratories. The here proposed project is based on a previous project where we built up a cavity ringdown (CRD) experimental setup. We now plan to further develop the CRD setup to (A) implement a new CRD operational mode, (B) introduce a new high pressure fast opening valve into the experiment, (C) allow for double resonance (DR) experiments using a millimeter chirped pulse setup in combination. The new CRD operational mode is important to be able to synchronize the CRD to ultra-fast molecule production techniques like laser ablation. The high-pressure fast opening valve will be crucial for a more efficient cooling of the investigated molecules, and the DR experiments will be important for the correct analysis (e.g., quantum number assignments) of more complex spectra where vibrational modes start to perturb each other. Our team at the laboratory in Kassel has long-time experience in the field of molecular spectroscopy and the production and analysis of molecules. When putting the proposed project into effect we will be able to provide data that is of high relevance for observers and modelers of astrophysical environments, but also for theoreticians that work on ab-initio models of molecules.

• DFG Programme: Research Grants