Coupled capillary wave fluctuations in thin aqueous films on an aqueous subphase

X-ray scattering and interfacial tension measurements are used to demonstra te the formation of nanometer-thick aqueous films on aqueous bulk subphases from polymer-salt biphase mixtures. X-ray scattering determines a coupling constant that characterizes the coupled capillary wave fluctuations of the liquid-vapor and liquid-liquid interfaces of this thin film. These data al so determine an effective Hamakar constant that characterizes the long-rang e interaction between the interfaces and parameters that characterize the s hort-range part of the interfacial interaction.