Picosecond kinetics of strongly coupled excitons and surface plasmon polaritons

Coupling between excitons of CdSe nanocrystal quantum dots (NQDs) and surface plasmon polaritons (SPPs) of an Ag film attached to a prism have been studied by steady-state and transient reflectivity measurements in the Kretschmann geometry. In these experiments, the angle of incidence of the probe beam selects hybrid exciton/SPP states with different wavevectors and exciton/SPP compositions. The dynamics measured in the transient reflectivity experiments are sensitive to the composition of the hybrid states. Specifically, fast dynamics are observed at probe wavevectors where the lower hybrid state has predominant SPP character. In contrast, at probe wavevectors where the lower hybrid state is predominantly excitonic, the dynamics are similar to that measured for CdSe NQDs on glass.