R. Stommer et al., X-RAY DIFFUSE-SCATTERING IN LANGMUIR-BLODGETT MULTILAYERS PREPARED FROM FATTY-ACID SALTS, Journal of physics. D, Applied physics, 28(4A), 1995, pp. 216-219
Multilayers from fatty acid salts, such as Pb or Cd stearate, exhibit
a perfect lamellar stacking along the surface normal but a powder-like
behaviour in the plane. The amphiphilic molecules are arranged into s
ingle-crystalline domains, which are randomly distributed around the s
urface normal. Using x-ray scattering methods, our films show strong r
esonant as well as non-resonant diffuse scattering in non-specular dir
ections. The off-specular scattering of lamellar systems is usually de
scribed by Sinha's model, which considers the diffuse scattering from
rough interfaces as the main process. We present an alternative model,
which takes the two-dimensional small-angle scattering of randomly di
stributed domains into account.