TADIM · Tayloring Decoherence in Large Molecules

Large molecules, i.e. molecules with more than 10 or even 20 atoms, have a huge potential to provide new data for the elaboration of new physics, from probing dark matter models, variations of fundamental constants or testing the Standard Model beyond what can be achieved by high-energy experiments conducted at large and very costly facilities. However, these large molecules can suffer from very complex couplings, making high-precision measurements almost impossible once a certain number of atoms, and thus of molecular complexity, is reached. When probing vibrations of the molecule (spectroscopically, in the IR frequency domain), couplings between different vibrational modes of the same molecule can induce large linewidths, and decoherence of the vibrational states. These vibrational couplings are called intramolecular vibrational redistribution (IVR) in the physical chemistry litterature, and are known since more than 40 years, but a detailed understanding of these processes is still lacking. Progress in that field is thus of paramount importance for the development of new experiments involving large molecules for the advancement of physics, and for the understanding of how vibrational energy is stored and can flow in a molecule.The project will explore experimentally IVR in large molecules with cutting-edge spectroscopic tools, to progress in removing this major blockade in the use of large molecules to look for new physics. Probing IVR in a very detailed way is enabled by recent advances in the production of cold molecules and ultra-high-resolution mid-infrared spectroscopy. These new techniques will allow me to develop and demonstrate a new methodology to study IVR at an unprecendented precision. The main output will be a recipe to tailor IVR in molecules, from the molecular structure point-of-view, as well as the demonstration of unparalleled spectroscopic resolution on molecules with more than 20 atoms.