Tracking of single molecules as a powerful method to characterize diffusivity of organic species in mesoporous materials

Abstract

The diffusion of individual fluorescent molecules can be observed by single-molecule tracking techniques and characterized by the analysis of their diffusional trajectory. Heterogeneities in the diffusivity that would pass undetected by conventional ensemble methods or fluorescence correlation spectroscopy are resolved by this method. This is demonstrated using four different examples in which we analyse the diffusion of single organic dye molecules in mesoporous materials. We show that this method can be used to obtain structural information from the inner structure of nanoporous materials with a resolution better than the optical diffraction limit.