Connecting the ensemble and single-molecule optical properties of quantum dots for their use as quantitative fluorescence probes

by Heyes, Colin D.

The optical properties of quantum dots are complex and not well understood. These complex optical processes include multi-exponentially decaying emission, fluorescence intermittency (blinking), fluorescence quenching and the observation of a dark (non-fluorescing) fraction in the sample. Nevertheless, these nanomaterials are finding many applications in the biophys. field as fluorescent probes due to their high brightness, excellent photostability and long photolumenscence lifetimes. Extg. quant. information from these studies remains a challenge due to the complexity of the obsd. optical signals. By observing the emission from single quantum dots, and comparing the signal to that obsd. from the ensemble, we are attempting to gain a more thorough understanding of the connection between the microscopic physics and chem. of the quantum dot and the emsemble optical properties. In this talk, I will discuss our obsd. shell and soln. pH dependence on the optical properties to draw connections between blinking and dark fraction formation, quantum yield and fluorescence lifetime decay. We hope that this work will extend the use of quantum dots as quant. fluorescence probes.