COMPETING INTERACTIONS AND DOMAIN-SHAPE INSTABILITIES IN A MONOMOLECULAR FILM AT AN AIR-WATER-INTERFACE

Domain-shape instabilities are investigated in a two-dimensional binary mixture of near-critical composition, a monomolecular film confined to an air-water interface and composed of a phospholipid and cholesterol. We apply the methodology of spectral analysis to the quantitative description of domain-wall configurations. This permits us to identify an elliptic instability and a branching instability leading into a stripe phase in the vicinity of the consolute point. In between, a regime exists in which domain-wall fluctuations exhibit a capillary-wave spectrum. © 1990 The American Physical Society.