Here is a new paper accepted for publication in Physical Review Letters, where we demonstrate that a molecular vibration can be ultra-strongly coupled to multiple infra-red cavity modes, with Rabi splittings reaching 24% of the vibration frequencies. This effect induces a whole vibrational ladder of heavy polaritonic states perfectly resolved. The vibrational ultra-strong coupling regime,  which impact both the optical and the molecular properties of the coupled systems, thus offers promising possibilities in particular in the context of mode-selective chemistry. For now, you can read our work on arXiv and also download it from our publications page.