Diffusion of Single Molecules Close to Interfaces

Abstract

The diffusion of individual rhodamine 6G molecules in ethylene glycol close to a glass interface has been studied. Diffusion coefficients are analyzed by photon burst analysis. It is shown that the diffusion of dye molecules becomes slower near the interface as compared to the bulk value. We attribute this to anomalous diffusion of molecules next to the interface, due to attachment and detachment of molecules caused by molecule surface interaction. The analysis of the measurements is tested by computer simulations of fluorescence bursts.