Fluorescence correlation spectroscopy (FCS) was used to investigate the translational diffusion of a fluorescent dye embedded at a dilute concentration in a confined fluid at rest and during shear. Octamethylcyclotetrasiloxane (OMCTS), confined between step-free muscovite mica to thickness 3-4 layers was used for the investigation. The time scales of intensity-intensity autocorrelation functions were shown to be same during shear and at rest, except they were found to be faster by a factor of 2 to 5, by fluorescence correlation spectroscopy. The results show that the activation volume for diffusion exceeds in the bulk liquid by ≈ 3 orders of magnitude.
ASJC Scopus subject areas
- Physics and Astronomy(all)