Specular and diffuse scattering of highly aligned phospholipid membranes

We present a quantitative study of specular and diffuse (nonspecular) x-ray and neutron reflectivity from highly aligned phospholipid membranes deposi ted on solid substrates, The height-height correlation function could be ob tained from the diffuse scattering without further model assumptions. The r esults differ significantly from the linear theory of smectic elasticity. W e argue that the diffuse scattering is dominated by static liquid-crystalli ne defects, rather than thermal fluctuations. [S1063-651X(99)07312-2].