The use of size distributions of circular domains in Langmuir monolayers for determining physical parameters of surfactants

An analysis of equilibrium size distributions of circular liquid-condensed (LC) domains in amphiphilic monolayers at the air/water interface, gleaned from microscopic images, is presented in terms of Gaussians fitted to a theoretical expression derived previously. It is demonstrated how, in principle, important properties of the monolayer, such as molecular dipole moments of surfactant head groups and line tension of the liquid-condensed/liquid-expanded phase boundary, can be obtained by combining the results of this simplified analysis with information from X-ray diffraction or surface pressure measurements.