Excited State Dynamics of CO₂ Reduction Catalyst under Vibrational Strong Coupling

Molecular polaritons, formed by coupling molecular electronic or vibrational transitions to photonic modes in microcavities, have gained interest for their potential to influence chemical dynamics. Here, we investigate the effects of vibrational strong coupling (VSC) on solvation-induced time-dependent Stokes shifts using transient infrared (IR) transmission spectroscopy. The electronic excited-state dynamics of the Re(bpy-COOH)(CO)3Cl complex (ReC0A) is monitored via angle-resolved time-dependent transmission spectra of vibrational polaritons following 400 nm excitation inside a Fabry–Perot cavity. Our results reveal distinct infrared polaritonic signatures of the CO dynamical Stokes shift, which we interpret using simulations based on a time-dependent excited-state absorption model. We observed negligible change of the solvation-induced vibrational dynamic Stokes shift of the CO modes under VSC. We also investigate the perturbed free induction decay in the cavity and its connection to polariton dynamics. This setup allows us to probe and test potential fundamental VSC effects on molecular processes relevant to the reactivity and charge transfer.