Coherent X-ray scattering and speckle pattern of solid-supported multilayers of surfactant bilayers

Charged surfactant bilayers deposited in thick multilayer films and swollen in vapor or in solution have been studied by coherent X-ray scattering. We report a pronounced static speckle pattern which persists under conditions of full hydration, despite the fact that the bilayers are fluid, relatively soft, and consisting of soluble amphiphiles (DDABr). Characteristic of the macroscopic domains size, the speckle pattern is observed in the plane of incidence (rocking curves). Contrarily, out-of-plane scans, which probe smaller lateral distances along the multilayer, exhibit a smooth diffuse scattering curve characteristic of thermal fluctuations of membranes.