X-ray reflectivity study of interface roughness, structure, and morphology of alignment layers and thin liquid crystal films

We report results of x-ray reflectivity studies of thin conducting films, organic alignment layers, and liquid crystal films on flat glass substrates. An understanding of these films is important for liquid crystal science and technology. Specular reflectivities of conducting layers of indium tin oxide, organic overlayers of lecithin, 12-8 (poly)diacetylene polymerized with linearly polarized uv light, and spin-coated diheptylazoxybenzene films were measured. The evolution of surface roughness of soda-lime glass substrates as a function of chemical etching time was also studied. Using theoretical models based on the Fourier transform of electron density gradients and the matrix formalism of x-ray optics, we quantitatively determined film thickness, layer spacing, electron density, and rms surface roughness and height-height correlations.