Photodynamics of single quantum dots

• Main Author: Lee, Steven Frank
• Published: University of Sussex 2009
• Subjects: 621.38152
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494932

A range of photochemical processes in biologically compatible quantum dots (QDs) at the individual nanocrystal level has been examined. Using objective type total internal reflection fluorescence microscopy we demonstrate the observation of photoluminescence activation (PLA), enhancement (PLE), fluorescence intermittency (Fl), decay and spectral shifting over the photochemical lifetimes of single QDs. The ability to count individual QDs along with their intensities has revealed a measurable nonlinear correlation between the total fluorescence and the QD population that is the result of enhancement and decay in the quantum yield (QY) of individual dots. This allows the differentiation between ensemble photoluminescence enhancement due to the fluorescence activation of a dark, non-emitting fraction of QDs (PLA) and that due to genuine QY modification in individual nanocrystals (PLE).