Measurements of the adsorption kinetics of a cationic surfactant in a liquid jet by ellipsometry

new technique for the study of the kinetics of adsorption of surfactants at the air-water interface on the 1-20 ms time scale is described. Ellipsomet ric measurements were performed directly on the surface of a high-speed jet containing a solution of hexadecyltrimethylammonium bromide (CTAB), The co efficient of ellipticity was converted to surface concentration with the ai d of neutron reflection data obtained previously on an overflowing cylinder . By this method, the surface concentration in the jet can be measured with a precision of 5% of a monolayer. An approximate measure of the interfacia l age was obtained from the speed of the jet. The experimental data were te sted against theoretical predictions and found to be consistent with diffus ion-limited adsorption within the error of the experiment. Experimental dat a obtained at different jet speeds were in good agreement, suggesting that Marangoni effects did not play an important role.