Large amplitude motion within acetylene–rare gas complexes hosted in helium droplets

Abstract

Near-infrared spectroscopy of the C₂H₂–Ar, Kr complexes was performed in the spectral region overlapping the ν₃/ν₂ + ν₄ + ν₅ Fermi-type resonance of C₂H₂. The experiment was conducted along the HElium NanoDroplet Isolation (HENDI) technique in order to study the coupling dynamics between a floppy molecular system (C₂H₂–Ar and C₂H₂–Kr) and a mesoscopic quantum liquid (the droplet). Calculations were performed using a spectral element based close-coupling program and state-of-the-art 2-dimensional potential energy surfaces to determine the bound states of the C₂H₂–Ar and C₂H₂–Kr complexes and simulate the observed spectra. This furnished a quantitative basis to unravel how the superfluid and non-superfluid components of the droplet affect the rotation and the deformation dynamics of the hosted complex.