Chemical and physical aspects of charge transfer in the fluorescence intermittency of single molecules and quantum dots.

We propose a synthetic view of the blinking of single molecules and single semiconductor nanocrystals, in which chemical and physical viewpoints play equally useful and important parts. The initial steps of charge transfer involve photophysical and physical processes. Trapping and stabilization of the separated charges are quick processes which can be described in physical terms, but which often lead to new chemical species. This is in particular true in fluid solutions, where many chemical and redox reactions become possible. Recent work has demonstrated how the addition of both oxidizing and reducing agents in the solution can help control the blinking rates of dye molecules and improve their photostability.