Interferometric Studies of Thick Film Critical Behavior

Abstract

Consider a film of thickness L ≈ 1 µm, consisting of a critical binary fluid mixture trapped between parallel flat surfaces. Scaling theory supplies a number of predictions regarding the effects of restricted geometry on the critical properties of such a film.¹ These are based on the ansatz that the relevant scale of thickness for the film is determined by the bulk correlation length ξ(T) which scales with the 3d critical exponent ν. ξ diverges, and becomes comparable to L as the film temperature approaches the bulk critical temperature, T_c∞; at which point the presence of the walls introduces a constraint which lowers the symmetry of the system.