Conformal Roughness in the Adsorbed Lamellar Phase of Aerosol-OT at the Air−Water and Liquid−Solid Interfaces

At concentrations greater than the critical micellar concentration, cmc, Aerosol-OT, AOT, adsorbs at the air−water and liquid−solid interfaces as a lamellar phase, with long-range lamellar ordering normal to the surface or interfaces. Coincident with the specular Bragg scattering from the ordered structure is pronounced off-specular scattering, characteristic of conformal roughness in the multilayer structure. A detailed analysis of the off-specular scattering, interpreted in terms of a correlation length of the conformity and an amplitude of the fluctuations, is presented. Additional off-specular scattering is observed, and its origin, arising from an effect analagous to that responsible for Newton's interference fringes in optics, is discussed. Analysis of both the specular reflectivity and off-specular scattering is consistent with increasing structural order with increasing temperature.