LATERAL DIFFUSION OF ACRIDINE-ORANGE AT LIQUID-HYDROCARBON WATER INTERFACES

The lateral diffusion coefficient of acridine orange was measured for a series of liquid alkane/water interfaces. The data show that the lat eral diffusion coefficient differs among these interfaces and that lat eral diffusion is slowed by interfacial roughness. Hydrocarbon viscosi ty had previously been suggested to play a role: analogous measurement s for a C-18/water interface indicated that the reconfiguration of the hydrocarbon controls the lateral diffusion coefficient. However, the results of this work show that hydrocarbon viscosity does not signific antly influence the lateral diffusion of acridine orange at liquid hyd rocarbon/water interfaces. A simple mathematical model is developed to provide a plausible explanation for the observations that interfacial roughness slows lateral diffusion for liquid/liquid interfaces and hy drocarbon viscosity has less of an effect for liquids than for viscous monolayers.