![Structures and Dynamics of Ultra-thin Smectic Films Structures and Dynamics of Ultra-thin Smectic Films](/3636717/header_image-1599470476.jpg?t=eyJ3aWR0aCI6ODQ4LCJmaWxlX2V4dGVuc2lvbiI6ImpwZyIsIm9ial9pZCI6MzYzNjcxN30%3D--600b76d89916ead2d3af5f5934b9e0e23d1e7eef)
Structures and Dynamics of Ultra-thin Smectic Films
![Fig 1: AFM height images (area 20 x 20 μm2) of ultra-thin (two to three molecular layers) smectic films spin coated from solution onto silicon wafers. The concentration of the smectic compound (8CB) in the spin-coating solution was 2.8 mg/ml (a), 3.0 mg/ml (b), 3.2 mg/ml (c), 3.4 mg/ml (d), 3.6 mg/ml (e), and 3.8 mg/ml (f). The images demonstrate the partial formation of the smectic top layer: with increasing concentration, a structural sequence is observed which starts with isolated islands which grow to a porous structure and finally form a complete layer. The height difference between the thicker and the thinner parts of the film is about 3.2 nm, corresponding to the thickness of one molecular smectic layer.](/3205665/original-1518437630.jpg?t=eyJ3aWR0aCI6MjQ2LCJvYmpfaWQiOjMyMDU2NjV9--8d3aeb4ee4ab765926f5853214a0149cdf808cb1)
Fig 1: AFM height images (area 20 x 20 μm2) of ultra-thin (two to three molecular layers) smectic films spin coated from solution onto silicon wafers. The concentration of the smectic compound (8CB) in the spin-coating solution was 2.8 mg/ml (a), 3.0 mg/ml (b), 3.2 mg/ml (c), 3.4 mg/ml (d), 3.6 mg/ml (e), and 3.8 mg/ml (f). The images demonstrate the partial formation of the smectic top layer: with increasing concentration, a structural sequence is observed which starts with isolated islands which grow to a porous structure and finally form a complete layer. The height difference between the thicker and the thinner parts of the film is about 3.2 nm, corresponding to the thickness of one molecular smectic layer.
![Fig. 2: Mean film thickness, as determined by ellipsometry (black dots, left axis: ellipticity coefficient ρ, right axis: resulting mean thickness h) and by analyzing the AFM images (blue diamonds, right axis only), as function of the concentration c of the liquid crystal compound 8CB in the spin coating solution.](/3205674/original-1518437631.jpg?t=eyJ3aWR0aCI6MjQ2LCJvYmpfaWQiOjMyMDU2NzR9--8e74976dae5a59f5b94f1cb83a2967f716793822)
Fig. 2: Mean film thickness, as determined by ellipsometry (black dots, left axis: ellipticity coefficient ρ, right axis: resulting mean thickness h) and by analyzing the AFM images (blue diamonds, right axis only), as function of the concentration c of the liquid crystal compound 8CB in the spin coating solution.
![original](/3205683/original-1518437631.jpg?t=eyJ3aWR0aCI6MjQ2LCJvYmpfaWQiOjMyMDU2ODN9--f3554fd6834d0184fefba132107c482f446c60de)
![Image processing enables the determination of the trajectories of the probe molecules and from the mean square displacement the diffusion coefficient is obtained.](/3205692/original-1518437631.jpg?t=eyJ3aWR0aCI6MjQ2LCJvYmpfaWQiOjMyMDU2OTJ9--bd731a085a86e1a4d7e1eea441126e379fb7eaa9)
Image processing enables the determination of the trajectories of the probe molecules and from the mean square displacement the diffusion coefficient is obtained.