By combining total internal reflection fluorescence cross-correlation spectroscopy with Brownian dynamics simulations, we were able to measure the hydrodynamic boundary condition of water flowing over a smooth solid surface with exceptional accuracy. We analyzed the flow of aqueous electrolytes over glass coated with a layer of poly(dimethylsiloxane) (advancing contact angle Θ $=$ 108°) or perfluorosilane (Θ $=$ 113°). Within an error of better than 10 nm the slip length was indistinguishable from zero on all surfaces.

• Received 30 January 2013

DOI:https://doi.org/10.1103/PhysRevE.87.051001