Transient studies of vibration-cavity polaritons

Vibration-cavity polaritons, which are produced by strong coupling between an optical cavity and a molecular vibration, can modify chemical reaction rates and branching ratios. However the observed effects are poorly understood. To gain insight into how these polaritons might alter molecular processes, we used ultrafast pump-probe and two-dimensional infrared spectroscopies to characterize polariton excited state dynamics. Our earlier studies on vibration-cavity polaritons with tungsten hexacarbonyl demonstrated that much of the response is due to so-called reservoir or uncoupled excited state absorption as well as polariton contraction. In recent studies, we have used 2D IR and spectrally filtered pump-probe studies on the nitroprusside anion in methanol to determine the transition frequencies and dynamics of polariton excited states allowing us to extract polariton dephasing timescales as well as incoherent polariton population which at a significantly longer timescale.