Observation of correlated emission intensity and polarization fluctuations in single CdSe/ZnS quantum dots.

Time-resolved single-nanoparticle spectroscopy has been carried out to examine the luminescence characteristics of individual CdSe/ZnS core/shell quantum dots. In particular, the possible correlations between emission intensity, lifetime, spectrum, and polarization fluctuations have been investigated. The emission polarization was found to be correlated with the luminescence intensity in a nonlinear way. The low-emissive states were found to correlate with red-shifted spectrum, increased nonradiative decay, and low degree of emission polarization. The observations are consistent with the model that charged quantum dots can be emissive.