State-Selective Polariton to Dark State Relaxation Dynamics

The modification of vibrational dynamics is essential for controlling chemical reactions and IR photonic applications. The hybridization between cavity modes and molecular vibrational modes provides a new way to control molecular dynamics. In this work, we study the dynamics of vibrational polaritons in various solvent environments. We find the dynamics of the polariton system is strongly influenced by the nature of the solvents. While the relaxation from upper polariton (UP) to dark modes is always fast (<5 ps) regardless of the medium, lower polariton (LP) in a nonpolar solvent shows much slower transfer (10-30 ps) into dark modes, despite the LP lifetime remains within 5 ps. This result indicates in this case, LP first relax into intermediate states before fully transfer to dark modes. In contrast, in solvent environments that strongly interact with solutes, the LP population relaxes into the dense dark state manifold within a much faster time scale. We propose the intermediate state to be the high-lyi...