Comparing the activation energy of diffusion in bulk and ultrathin fluid films.
We have measured the activation energy (E act) of translational diffusion for a dissolved fluorescent dye in bulk and within an ultrathin liquid film formed on a solid substrate. The experiments were performed using the single-molecule sensitive technique of fluorescence correlation spectroscopy. From the temperature-dependent measurements, we have determined that the activation energy for a few nanometer thick fluid film increases by a factor of approximately 3-4 compared to bulk liquid. The results are confirmed for two distinctly different systems in regard to molecular shape, tetrakis (2-ethylhexoxy) silane and hexadecane.
Grabowski
Christopher A
CA
Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201, USA.
Mukhopadhyay
Ashis
A