The effect of inhibition of molecular reorientation and the resulting consequences for the dilatational elastic modulus

Surface light scattering investigations of the propagation of thermally exc ited capillary waves on the surface of a surfactant solution (triisopropylp hosphine oxide) have been carried out. The surfactant had a specifically de signed geometry, to eliminate the possibility of molecular reorientation in the absorption layer. The absence of such motions are demonstrated by the absence of any deviation in the dilatational elastic modulus from the value calculated from the equilibrium surface tension versus concentration isoth erm, at concentrations appropriate to reorientation in ordinary surfactant adsorption layers.