On the spectrum of interlayer roughnesses in a phospholipid multilayer

The spectral properties of the correlation function of the heights of interlayer boundaries in a lamellar 1,2-distearoyl-sn-glycero-3-phosphocholine film deposited on the surface of the hydrosol of amorphous silica nanoparticles are investigated within the scope of a model-independent approach based on the data of nonspecular X-ray scattering. The data analysis shows that the spectrum of interlayer roughnesses in a multilayer is qualitatively different from the prediction of the capillary wave theory in the entire considered interval of spatial frequencies.