J. Hutchison et al., Measurements of the adsorption kinetics of a cationic surfactant in a liquid jet by ellipsometry, LANGMUIR, 15(22), 1999, pp. 7530-7533
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.