Enhancement of multiphoton emission from single CdSe quantum dots coupled to gold films.

Single molecule time-resolved fluorescence spectroscopy of CdSe/ZnS core-shell quantum dots (QDs) localized near a rough gold thin film demonstrates significant enhancement of multiphoton emission while at the same time showing a decrease in single photon emission. A rigorous analysis of time-resolved photon correlation spectroscopy and fluorescence lifetime data on single quantum dots at room temperature reveals an increase in radiative recombination rate of multiexcitons that is much higher than expected and, perhaps more significantly, is not correlated with concomitant increases in single exciton recombination rates. We believe that these results confirm a stronger coupling of multiexcitons to plasmon modes via a coupling to plasmon multipole modes.